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Virus test For COVID-19

Virus Test For COVID-19

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Virus Test For COVID-19

In this article：

COVID-19 variants_Omicron;

symptoms;

Swab Test;

COVID-19 is an infectious disease,a respiratory disease.

COVID-19 variants_Omicron

The new findings indicate that the new mutation of COVID-19, Omicron, spread earlier than everyone thought, and the scope is wider.

We must do a good job in vaccine injection and virus swab testing is the top priority.
According to the Associated Press, on Tuesday (November 30), the new findings have clearly shown that Omicron has entered many countries before the world has created its own protection system for Omicron.

The Spanish Institute of Public Health Service and Natural Environment (RIVM) detected Omicron in virus samples on November 19 and 23.

According to the World Health Organization, South Africa first reported this type of mutant virus on November 24.

At this stage, it is still not clear where this type of mutation first occurred, nor how infectious it is, but this has not prevented some countries from rushing to implement travel restrictions, especially for tourists from southern Africa.

This measure has been criticized by South Africa, and the WHO has also expressed its resistance, feeling that its actual effect is relatively limited.

The latest developments have also become increasingly clear that the travel ban cannot prevent the spread of new mutations.

The German government stated that they had seen Omicron in a man who had neither been to Africa nor had any knowledge of anyone who had contracted this type of virus.
The World Health Organization reminded on Monday that the risk of Omicron’s worldwide spread is “very high”, and initial direct evidence suggests that it is likely to be more infectious.

The COVID-19 pneumonia epidemic broke out for the first time nearly two years ago, and at this stage, the world’s response at many levels is similar to the disorder two years ago. Including random implementation of travel restrictions, and the lack of grasp of where there are risks and where there are risks.

Senior officials from all over the world try to clear everyone’s fears, saying that their vaccines are still a better way of defense. Be sure to continue to work hard to make vaccination spread all over the world. At the same time, do a virus swab test.

However, regarding the effectiveness of vaccines against Omicron mutations, although the President of the United States is also urging vaccination, the White House President’s medical consultant and the top infectious disease expert in the United States told the ABC TV program on Monday that the experts look forward to one or two in the future. Understand within a week.

What is the maintenance level of the current COVID-19 vaccine against this new mutation? Don’t know yet. But what we can do is to do a good job of virus swab testing and prevention. For example, go out less and party less.

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COVID-19 symptoms;

The symptoms of COVID-19 are likely to include dysosmia, high fever, dry cough, dyspnea, chills, headache, muscle pain, sore throat, hematoma, or runny nose. At the same time, it is manifested as conscious fatigue, weakness, and weakness.
This situation may happen 2-14 days after you touch the virus that causes COVID-19.
Not all COVID-19 patients have all of these symptoms, and some people have no symptoms. That is an asymptomatic infection.
Even after recovering from COVID-19, some people are still likely to have unforgettable illnesses, such as fatigue, dry cough, or joint pain. The long-term physical and mental health hazards are unclear, but they may cause permanent damage to the cardiovascular system, lungs, or other human organs. This is more likely to occur in people with more serious illnesses, but it is more likely to occur even in people with milder illnesses.
If you have symptoms, please take a swab. If you have questions or concerns about a medical condition, please consult your health service provider.
For other information, please visit WTO: COVID-19 symptoms.

COVID-19 Swab Test;

We are still learning more about new virus testing and will share it when we get new information.

Covid-19 Virus test key information

Updated on December 6, 2001

Other languages: covid-19 key information

Amharic Covid-19 swab test key information (PDF)

The Philippines Covid-19 nasal swab test key information (PDF)

Singapore Covid-19 swab test key information (PDF)

Malaysia Covid-19 flocked swab test key information (PDF)

Malta Covid-19 swab test key information (PDF)

Brunei Covid-19 swab test key information (PDF)

Qatar Covid-19 swab test key information (PDF)

Indonesia Covid-19 swab test key information (PDF)

United Arab Emirates Covid-19 swab test key information (PDF)

Hong Kong Covid-19 swab test key information (PDF)

Britain Covid-19 swab test key information (PDF)

The United States Covid-19 swab test key information (PDF)

Canada Covid-19 swab test key information (PDF)

Ireland Covid-19 swab test key information (PDF)

New Zealand Covid-19 swab test key information (PDF)

Australia Covid-19 swab test key information (PDF)

Thai Covid-19 swab test key information (PDF)

Saudi Arabia Covid-19 swab test key information (PDF)

Nigeria Covid-19 Virus swab test key information (PDF)

India Covid-19 swab test key information (PDF)

South Africa Covid-19 swab test key information (PDF)

 

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Viral Swab Collection & Transport Kits | 3ml Tube

How to obtain a nasopharyngeal swab specimen?

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How to obtain a nasopharyngeal swab specimen?

Overview.

Nasopharyngeal swab specimen collection of respiratory mucosal surface specimens is a method for the diagnosis of Covid-19 novel coronavirus in adults and children.

This operation can also detect patients with suspected respiratory infections caused by other viruses and bacteria.

There are no special contraindications for nasopharyngeal swab specimens. However, clinicians should treat the following conditions with caution: the recent history of nasal trauma or surgery, severe nasal septum deviation, chronic nasal obstruction, and severe coagulation.

Preparation for nasopharyngeal swab specimen sampling.

The nasopharyngeal swab is a special sampling tool, which consists of a sampling head made of soft plastic or flocked nylon. In addition to nasopharyngeal swabs, operators also need personal protective equipment (PPE) such as isolation gowns, non-sterile gloves, protective masks, and face shields.

Before starting to use, please make sure that all virus sampling tubes are labeled, and the analysis application form is filled incorrectly.

Nasal Swab Sampling Steps

We recommended that patients with suspected Covid-19 type coronavirus infection wear masks.

The patient took off the mask and blew his nose with a paper towel to remove excessive secretions from the nasal passages.

Take out the tissue. Slightly lift the patient’s head so that it can wipe into the nasal passage. Ask the patient to close his eyes to alleviate the slight discomfort caused by the operation.

Along the nasal septum, gently push the swab above the bottom of the nasal passage forward until you feel a sense of resistance indicating that the swab has reached the nasopharynx.
Insert the swab in the nostril parallel to the upper jaw.

If resistance is encountered during pushing the flocked swab, the scraper should be withdrawn, try to adjust the angle and then push again, at the same time closer to the bottom of the nasal passage.

The depth of the nose insertion should be equal to the distance from the nostril to the opening of the external auditory meatus. CDC recommends keeping the sampling head for a few seconds after it reaches the nasopharynx, allowing the sampling head to absorb the secretions, and then slowly rotating the swab to discharge it slowly (people who have done nasopharyngeal swabs will appreciate which kind of sourness Cool feeling). Your institution may also recommend sampling for a few weeks after exiting the spin. Ask the patient to wear a mask.

Nasopharyngeal swab specimen processing.

Open the sampling tube with virus transport medium, put in the flocking swab, fold out the sample tube in the groove, and discard the tail. Tighten the label sampling tube cover, and wipe the sampling tube with a sterile wipe.

Then place the sampling tube in the biohazard bag opened by the assistant. Some departments may require you to put the samples back in their original packaging and then send them for inspection. According to CDC guidelines, process the swab sample directly, or put the sample in a preservation solution or store it at room temperature.

Flocked Nylon Swabs and Non-Flocked Rayon Swabs

Flocked Nylon Swabs and Non-Flocked Rayon Swabs

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Flocked Nylon Swabs and Non-Flocked Rayon Swabs

Flocked swabs are famous for their stable and reliable performance and excellent absorption and elution ability.

Type of sampling swab.

1. Polyester fiber, polyester or rayon head, plastic or aluminum handle swab: it is suitable for the collection of virological test specimens. Swabs with wooden handles should not be used for the collection of virological test specimens.

2. Cotton swab: it is suitable for the collection of vaginal, cervical and urethral samples for Mycoplasma test, but not for the collection of bacteria (especially caustic bacteria) and Chlamydia test samples.

3. Polyester swab: suitable for sampling virus and bacterial samples.

4. Flocked swabs: made of nylon fibers by proprietary spray technology, suitable for sampling respiratory viruses and fungal culture samples.

5. Calcium alginate swab: it should be used for the collection of Chlamydia and botulinum pertussis nasopharynx swab. However, it is not suitable for the sampling of lipid coated virus and cell culture, Neisseria gonorrhoeae and Ureaplasma urealyticum.

Specimen Collection Swab.

Why choose flocked material as sampling swab material? What are its characteristics？

The unique test substrate greatly improves the yield of DNA;

Adult oral SWAB piece 1 to 10 μ g DNA;

It is a good alternative to blood collection;

Both human and animal can use it;

Simple and fast operation;

There are two types of single and double disinfection packaging to choose from;

application;

Genotype study;

Veterinary genotyping and diagnosis;

Parent child and genetic services;

Forensic and DNA population studies;

 

Features of Flocked Swab

Features of Flocked Swab

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Features of Flocked Swab-oral swab

Viral infection is a respiratory infection. Generally, the incubation period of virus infection is less than one week. The symptoms of virus infection are: pharyngeal conjunctival heat, respiratory tract infection, hemorrhagic cystitis, diarrhea, pericarditis, chronic interstitial fibrosis, fever, etc. The diet should be light, eat more vegetables and fruits, quit smoking and alcohol, and don’t eat spicy and stimulating food. At present, during physical examination, the health and Family Planning Commission requires hospitals to use nasopharyngeal swab or throat swab to detect the virus.

Flocked swabs of Cell medical are famous for their stable and reliable performance and excellent absorption and elution ability.

Flocked Swab Oral swab

Flocked Swab Oral swab

Features of oral flocking swab:

1、 Product features:

1. The vertical nylon flocked fiber structure at the head is like a soft brush, which can improve the collection effect of cell samples. It is not only non-toxic to microorganisms, but also greatly increase the collection and release of samples.

2. Single and independent packaging , avoid pollution.

3. Strict process conditions, without DNase and expandable human DNA.

4. The tube body is transparent and the inspection materials are visible.

5. Flocked swab unique patented casing design ensures the air circulation in the casing, prevents the inspection material from mildew due to the humid sealing environment, and avoids magazine pollution in the external air, which affects the inspection quality.

Looking for more? what is the difference between a pcr test nasal swab and an antigen test for covid 19? here.

2、 Flocked swab advantages:

1. For throat sampling of respiratory viruses such as influenza, swine influenza, avian influenza, hand, foot and mouth.

2. It can quickly adsorb trace samples and has high release aging rate.

3. the front end is more sophisticated, which is suitable for the extraction of cells in the fingernail seam of the victim or suspect.

4. The back end of the swab can be broken, which is conducive to the automatic extraction workstation for sample extraction.

5. The whole swab is packed in a transparent plastic tube to avoid biological pollution.

How to do a Nasopharyngeal Swab

How to do a Nasopharyngeal Swab

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How to do a Nasopharyngeal Swab?

Nasopharyngeal Flocked Swab

Nasopharyngeal Flocked Swab

Nucleic acid detection is to collect Nasopharyngeal swabs, sputum or lower respiratory tract specimens, real-time fluorescence RT-PCR detection of New Coronavirus nucleic acid, if positive, can be diagnosed with New Coronavirus infection, which is the basis for the diagnosis of new type of pneumonia. In addition to detecting the nucleic acid of the virus, it can also detect whether the virus in the specimen is highly homologous with New Coronavirus. If so, it can be diagnosed as New Coronavirus pneumonia. The virus is highly infectious and has the characteristics of human to human transmission, but the virus is sensitive to temperature and sunlight and ultraviolet rays.

Nasopharyngeal swab price：Welcome to email:flockedswabs@gmail.com

Nucleic acid detection and collection method:

(nucleic acid detection nasal swab)

1. Ask the patient to keep his head still and remove the secretions on the surface of the anterior nostril. The collector can stand on the side of the collector to reduce occupational exposure caused by coughing and sneezing and relieve the collector’s pressure.

2. Measure the distance from nostril to ear root with a swab and mark it by hand.

3. Gently insert the swab into the nostril in the direction perpendicular to the nose (face) through the nasal cavity, with a sense of touching the wall until the finger touches the nose, keep the swab in the nose for 15-30 seconds, and then rotate it gently for 3 times.

4. Put the swab into the virus delivery medium, break the swab rod and place it completely in the tube.

5. Tighten the pipe cover, mark it, put it in a plastic bag and seal it.

6. Send the samples for examination in time

swab test nasal swab

swab test nasal swab

1. With the aid of tongue depressor, the collector opens his mouth and makes an “ah” sound. The palate is lifted up to expose the posterior pharyngeal wall. The swab crosses the root of the tongue to reach the pharyngeal stenosis lesion, and quickly wipe the palatal arch, pharyngeal and tonsil secretions on both sides.

2. The nasopharynx swab was put into the virus delivery medium, and the auxiliary tube cover broke the swab rod to make it completely placed in the tube.

3. Tighten the pipe cover, mark it, put it in a plastic bag and seal it.

4. Send the samples for examination in time.

Flocked Tip Swab

Flocked Tip Swab

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Flocked Tip Swab| China Flocked Swab Factory and Manufacturers.

Detection of viral nucleic acid sequence based on reverse transcription polymerase chain reaction (RT-PCR) is the main means for large-scale screening of new coronary pneumonia.

Generally, nucleic acid detection technology has the characteristics of early diagnosis, high sensitivity and specificity.

And it has the advantages of sample collection and preservation, personnel operation, nucleic acid extraction.

The performance of the kit is the cause of false negative or false positive test results.

Flocked swabs are the main samples for PCR. In the selection of raw materials, flocked glue plays a key role in the collection and release efficiency of swabs. Whether to use high-quality aqueous flocking glue is the main factor affecting the water absorption and hydrophilicity of fluff. The experiment is to compare the sample collection effects of swabs flocked with different glues.

What is a flocked tip swab？

The top of the flocking swab is a nylon fiber structure.

Nylon fibers are deposited on the surface of plastic rod in a certain direction by electrostatic field to form brush layer.

The layers are completely parallel and perpendicular to the inner rod surface.

Flocked tip swab brush head can effectively collect samples.

Flocked tip swab factory Product advantages.

The flocked swab can completely capture the cell sample through the directional friction effect of the brush fiber layer.

The capillary movement between the nylon fibers at the front end of the flocking swab can form a strong hydraulic pressure for absorbing liquid or cell line samples.

Cell samples can also be evenly and neatly concentrated on the near surface of brush fibers, so more than 95% of the samples can be released finally.

Cell Medical (Dongguan) Co., Ltd.  has many years of experience in medical application molding and flocking treatment heads and swabs.

Our flocked swabs are famous for their stable and reliable performance and excellent absorption and elution ability.

Cell medical (Dongguan) Co., Ltd. Daily production of millions of flocked sampling swabs

Cell medical (Dongguan) Co., Ltd. Daily production of millions of flocked sampling swabs. flocked tip swab 

Sample Universal Viral Transport Medium Kits

Sample Universal Viral Transport Medium Kits

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Sample Universal Viral Transport Medium kits

Cell medical (Dongguan) Co., Ltd. disposable sample universal viral transport medium kits are composed of flocked swabs and test tubes with virus preservation solution (VTM).

The appearance of VTM is clear or red, and there are no precipitates, lumps and other insoluble visible foreign matters.

For collecting, storing and transporting human nasopharyngeal virus samples. Such as COVID-19, mycoplasma,  Chlamydia specimens collection, transportation and preservation.

Universal Viral Transport Medium for Viruses 

Test principle:

Virus: Composed of a nucleic acid molecule and protein or only protein, and the individual is small and the structure is simple. Because there is no cell structure, the virus cannot replicate itself, but invades its genes into the host cell, using the latter’s replication system to replicate new viruses. After the virus sample is collected, in order to maintain the viability of the virus sample and prolong the survival time of the virus in the sample, the sampling swab will be stored and transported in the transport medium.

Viral transport medium composition and inspection principle:

Viral Transport Medium

Viral Transport Medium

1. A combination of multiple antibiotics has broad-spectrum anti-bacterial and anti-fungal effects.

2. As a protein stabilizer, bovine serum albumin (BSA) can form a protective film on the protein shell of the virus, making it difficult to decompose and ensuring the integrity of the virus.

3. The neutral environment constructed by Hank’s buffer helps increase the survival time of the virus and the stability of infection.

4. Phenol red is an acid-base indicator, the discolouration area is 6.6 (yellow)-8.0 (red), and it will be red at 7.2-7.4.

The most stable pH of the outer protein of the virus is 7.2-7.4, which is also the pH range of Hank’s buffer.

If contaminated moulds or bacteria are not inhibited by antibiotics, they will multiply and release carbon dioxide to lower the pH. When the pH value is lower than 7.2-7.4, the stability of the outer protein of the virus will decrease and the decomposition will be accelerated. At this time, the appearance of the sampling solution will change from red to yellow.

What are the main components of  Viral Transport Medium(VTM)?

Hank’s solution base, gentamicin, fungal antibiotics, cryoprotectants, biological buffers and amino acids.

On the basis of Hank’s, adding HEPES and other virus stabilizing components can maintain virus activity in a wide temperature range, reduce virus decomposition speed and improve the positive rate of virus isolation.

How to use a universal viral transport medium?

Please read the instructions carefully before use.

Working conditions: room temperature

1. Take out the virus preservation solution.

2. Use a sampling swab for sampling.

3. Insert the swab into the tube containing virus preservation solution, break the tail, leave it in the preservation solution tube, cover the tube cover.

4. Store it at 2-4 ℃ and use it within 48 hours.

If it needs to be stored for more than 48 hours, please store it in the refrigerator at – 20 ℃.

VTM swab kit COVID-19: diagnostic vector transport medium.

VTM swab kit COVID-19: diagnostic vector transport medium.

Our VTM product features and advantages.

1. A virus transport medium (VTM) in line with the recommendations of who and CDC.

2. The product is safe, environment-friendly and non-toxic.

3. The universal viral transport medium adds special virus stabilizing components to maintain the structural stability of virus core protein and outer membrane protein for a long time.

4. It is especially suitable for influenza virus and other samples sampled through upper respiratory tract swabs.

5. Compatible with other detection reagents.

6. The reagent itself has a colour indication function, and obvious color change will occur when the product deteriorates, so as to avoid misuse caused by improper preservation.

COVID-19 Pooled Sample Testing:Improve sampling rate and reduce cost

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COVID-19 Pooled Sample Testing:Improve sampling rate and reduce cost.

With the advent of autumn and winter, the possibility of a new outbreak of COVID-19  is increasing.

COVID-19’s large-scale community screening is the main means to cope with the recent outbreak of small-scale epidemics at home and abroad.

At present, New Coronavirus’s mixed sample nucleic acid detection has become a routine method to effectively enhance the screening and detection of nucleic acid in community population.

The pooled sample test of covid-19 increase the sampling rate and meet the growing needs of low-risk populations.

Virus transport medium,disposable virus sampling tube

Virus transport medium,disposable virus sampling tube

What is a Pooled Sample Test?

“mixed detection”, that is, nucleic acid test of Pooled Sample.

On the one hand,it is a method to sample several people, such as 3 or 5 or even 10, and then put them into the same virus sampling tube.

On the other hand,pooled Sample means combining the same type of specimen from several people and conducting one NAAT laboratory test on the combined pool of specimens to detect SARS-CoV-2.

What is the significance of nucleic acid test in Pooled Sample?

COVID-19 Pooled Sample Testing Advantages

Because a virus sampling tube only puts one person’s sample, the cost will be very high, and the detection time is long, which is not suitable for large-scale nucleic acid detection.

In principle, the single sample sampling mode is only applicable to high-risk areas and key populations.

In order to improve sampling efficiency, shorten sampling time and reduce sampling cost. Multi Country selection of Pooled sample test scheme.

For example, when 5-in-1 mixed sampling test is used, the result is negative, which means that all five people are negative.

On the contrary, once positive or weak positive is found, it will be traced immediately.

Re collect single tube swabs for review, and then determine which of the 5 people is positive.

Therefore, the cost of 5-in-1 mixed mining is relatively low.

This also caused the 5-in-1 mixed sampling mode to be five times faster than the previous mode of using a virus sampling tube for a human sample.

One of the biggest disadvantages of sample merging is the decrease of associated test sensitivity.

Analyzing multiple samples in a single reaction effectively improves the flux, but it also dilutes a single sample and may reduce the weak positive signal from outside the detection limit.

In short, pooled sample testing is mainly used for large-scale screening to check asymptomatic coronavirus infected persons. It is suitable for large-scale testing projects such as schools, factories, units and urban areas. It has the advantages of efficient screening and resource saving.

Although reduced detection sensitivity is acceptable for screening services in asymptomatic populations.

However, When providing diagnosis for high-risk or symptomatic patients, we must give priority to the accuracy of the results.

The special preservation tube for Pooled Sample test uses medical grade PP as raw material, unique structural design and manufacturing process to prevent liquid leakage. And has the characteristics of high temperature resistance, high pressure resistance and high-speed centrifugation resistance.

Cell medical (Dongguan) Co., Ltd. produces virus sampling tubes of various specifications, both inactivated and non inactivated, disposable virus sampling tubes, pooled sample sampling tubes.
such as 1ml, 2ml, 3ml, 5ml, 10ml and other specifications.

Located in  Guangdong Province, in China,with complete qualifications.

Contact information required.E-mail:flockedswabs@gmail.com

 

Pcr test nasal swab and an antigen test difference for covid 19

Pcr test nasal swab and an antigen test difference for covid 19

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Pcr test nasal swab and an antigen test difference for covid 19

What is COVID-19?COVID-19 is an epidemic disease caused by SARS-CoV-2. An acute respiratory infectious disease broke out at the end of 2019. So far, WHO has been making the latest tracking report on the new pneumonia on the Internet every day.

What are the current methods of COVID-19 test?

Virus detection includes two types: nucleic acid amplification test (NAAT) (PCR test) and antigen test.

Antibody tests (also known as serological tests) can prove whether you have been infected in the past.

What is the COVID-19 PCR test?

PCR (polymerase chain reaction): similar to the natural replication process of DNA, its specificity depends on oligonucleotide primers complementary to both ends of the target sequence.

Basic principle: the basic principle of PCR technology is similar to the natural replication process of DNA. Its specificity mainly depends on the oligonucleotide primers complementary to both ends of the target sequence. It consists of three basic reaction steps: denaturation, renaturation and extension.

PCR test sample collection method include:

If the sample contains a virus, the researchers will extract its RNA.

Why use the PCR test ?

PCR nucleic acid examination is a direct detection of COVID-19 RNA in human body by sampling from the nasal cavity. The structure of virus is composed of DNA or RNA combined with external lipid protective capsule. Therefore, direct detection of virus DNA itself is the most accurate, fastest and effective new detection method. PCR nucleic acid test can detect infection immediately after the human body obtains the virus, and the accuracy is much higher than antibody test.

ABOUT PCR TEST_Pcr test nasal or Throat swab sampling

ABOUT PCR TEST_Pcr test nasal or Throat swab sampling

How does the PCR test nasal swab work?

Nasopharynx swab is to wipe the secretion of the patient’s nasal cavity or pharynx. And then make the secretion into smear for examination and bacterial culture to clarify what bacterial infection is in the patient’s nasal cavity and pharynx.

Nasal swab sampling procedure

1. Keep the patient’s head still and remove the secretions on the middle surface of the anterior nostril;

2. Gently and slowly insert the swab through the nasal cavity to the nasopharynx;

3. After encountering resistance, it reaches the posterior nasopharynx and stays for several seconds to absorb secretions;

4. Gently rotate and take out the swab and place it in the transport medium;

5. For the swab used for virological test, immerse the swab head into the virus delivery medium, discard the tail, and tighten the tube cover;

If it is necessary to collect from both nostrils, the sampler should use the same swab.

How does the antigen test work?

Rapid antigen detection can play an important role in guiding patient management, public health prevention and control decision-making and covid-19 monitoring.

It is especially valuable for grass-roots areas that may hinder clinical diagnosis and control due to lack of nucleic acid detection capacity or long detection time.

According to WHO, high specificity based on antigen detection indicates that the positive results indicate new crown virus infection.

For patients within 9 days of onset, sampling personnel can use antigen detection as a diagnostic test.

Especially for the staff of medical institutions, inpatients and visitors in the epidemic area.

When nucleic acid detection cannot be effectively implemented, antigen detection can be used as an important screening method.

Rapid antigen test sampling procedure.

Rapid antigen test sampling process

Rapid antigen test sampling process

 

Generally speaking, nucleic acid detection: it has high requirements for laboratory environment, detection personnel and instruments. The detection has high sensitivity and good specificity.Generally, we can get the results in 2-3 hours.

Antigen detection: it has low requirements for the laboratory. For early screening and early diagnosis. It is suitable for large-scale screening in grass-roots hospitals. we can obtain the results within 15 minutes at the fastest.

At present, PCR test nasal swab is widely used, and the sensitivity and specificity of antibody / antigen detection reagents are still limited. 

Each has its own emphasis and cannot replace each other. We should combine multiple virus detection methods.

It can effectively shorten the detection window period and improve the positive detection rate.

 

COVID-19 Testing:PCR swab test,antibody test, and antigen test difference

COVID-19 Testing:PCR swab test,antibody test, and antigen test difference

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COVID-19 Testing :PCR swab test,antibody test, and antigen test difference.

PCR swab test（Nucleic acid test） and antibody / antigen detection are important means to confirm COVID-19, and also one of the important processes for patients to diagnose. But do you know what their detection principle is? What are the sample types? What is the inspection process and what are the problems? 

COVID-19 nucleic acid test

Nucleic acid detection has the characteristics of early diagnosis, high sensitivity and specificity. At present, real-time fluorescence quantitative RT-PCR is the most widely used technology. PCR swab testing is a very effective way to identify SARS-COV-2.

1. Principle of COVID-19 test kits?

The researchers used sampling swabs to collect samples of the virus, targeting the unique gene sequence of the virus.

By PCR amplification of the virus sample, the target DNA sequence we selected increased exponentially.

Researchers can combine the amplified DNA sequence with pre added fluorescent labeled probe fragments to generate fluorescent signals.

The more target genes amplified, the stronger the cumulative fluorescence signal.

In Virus-free samples, no target gene was amplified. Therefore, researchers can not detect enhanced fluorescence signals.

That is, we do not carry COVID-19.

Therefore, nucleic acid detection is actually to detect the accumulation of fluorescence signal to determine whether there is viral nucleic acid in the sample.

COVID-19 test kits_PCR swab test（Nucleic acid test）

COVID-19 test kits_PCR swab test（Nucleic acid test）

 

2. What are the methods of covid-19 testing samples?

Generally, PCR nasal swab test, pharyngeal swab, nasopharyngeal swab, sputum, bronchial lavage fluid, alveolar lavage fluid, etc.

Sampling swab consists of a nylon flocked swab.what is a flocked swab?

3. Steps of PCR swab test for COVID-19.

At present, pharyngeal swabs are the main sampling method for the diagnosis of novel coronavirus infection. Correct sampling is the key to improve the accuracy of nucleic acid samples collected from pharyngeal swabs. What are the factors affecting the accuracy of nucleic acid samples collected from pharyngeal swabs? There are three main aspects:

Depth of throat swab collection?

How long is the throat swab in contact with the mucosa?

Pharyngeal swab sampling “dot to dot” or wipe?

 

(1) Oral and pharyngeal swab collection tips

1. Sampling position: sit or semi-sit in decuffine position, with head slightly raised and mouth open, and head resting on the wall or against the back of the chair.

2. Standard sampling operation: Sampling personnel press the tongue of the subject with tongue depressors.

Pharyngeal swabs should be performed on both sides of the pharyngeal tonsil with “Quick wipe up and down” and on the posterior pharyngeal wall with “Quick left and right wipe” . Repeat 3 to 4 times.

Avoid contact with tongue, teeth and gums.

If you feel uncomfortable, quit, take a break, and try again.

Oropharyngeal Sampling flocked swab diagram

Oropharyngeal Sampling flocked swab diagram

3. Precautions: Drinking water before oral and pharyngeal swab test will dilute the virus attached to the pharynx, especially drinking hot water will inhibit the activity of the virus.

In order to improve the accuracy of pharyngeal swab nucleic acid detection, we recommend that subjects do not drink water 15-30 minutes before the detection, so as to ensure the high accuracy of pharyngeal swab nucleic acid test.

 

(2) Nasopharyngeal swab collection tips

1.The sampling personnel shall collect samples from the side of the subject, and the subject shall pull down the mask to expose only his nostrils. If there is sneezing reflex, the subject can cover it with elbow or paper towel.

nasopharyngeal sampling diagram

nasopharyngeal sampling diagram

2. Standard sampling operation: “one insertion, two stops and three rotations” — measure the distance from the tip of the nose to the front of the ear, half of the insertion length, usually about 4 cm for adults; Stay for 15-30 seconds to absorb nasopharyngeal secretions (depending on tolerance, minimum stay for at least 3 seconds; Rotate the nasopharyngeal swab for 1 week and slowly remove it.

The above is for the reference of sampling medical staff and patients, let’s work together to defeat COVID-19!

(3)Store samples

Dip the flocked swab head into the cell preservation solution(Virus transport medium), and tighten the tube cap immediately after breaking the tail;

Storage, put the sample tube into a sealed bag for timely inspection, and the inspection process requires a strict transportation environment, 2-8 ℃ storage.

(4) PCR TEST

Researchers operate nucleic acid extraction, extract inactivated virus samples for subsequent nucleic acid detection, and can use automatic equipment such as nucleic acid extractor.

Fluorescence PCR nucleic acid detection, that is, on the machine detection, the extraction of fluorescence PCR amplification reaction, needs 70-80 minutes.

process pcr test

process pcr test

4. What are the problems in nucleic acid testing?

False negative, due to improper sampling, improper specimen preservation, the use of different types of specimens and the use of different manufacturers of reagents may lead to nucleic acid test results “false negative” and missed diagnosis;

■ High requirements for detection equipment or platform, high sensitivity RT-PCR instrument is expensive, laboratory cleanliness and operator requirements are also high;

■ Nucleic acid testing is time-consuming. It usually takes 4-6 hours to complete an RT-PCR test.

Therefore, when the nucleic acid test is negative.

Relevant personnel can increase the detection of IgM and IgG antibodies to make up for the shortcoming that nucleic acid detection is easy to cause missed diagnosis.

 

COVID-19 Testing serum antibody test

Seven days after novel coronavirus pneumonia, the serum specific antibodies gradually emerged. The first is immunoglobulin IgM antibody, and then IgG antibody.

Thus, an elevated IgM antibody indicates a recent acute infection, and an elevated IgG antibody indicates a previous infection.

The biggest advantage of serological testing lies in its convenience and short detection time, which can effectively break through the limitations of existing detection technology on personnel and sites and shorten the detection time.

Novel coronavirus infection can be diagnosed in suspected cases if the serum specific IgM and IgG antibodies are positive, the IgG antibody changes from negative to positive, or the recovery period increases by 4 times or more than the acute period.

antibody test sampling process_COVID-19 Testing

antibody test sampling process_COVID-19 Testing

1. Principle of serum antibody test kit?

The sample is added to the sample adding hole, and the sample will move forward along the detection card under the action of chromatography.

If the sample contains new coronavirus IgM antibody, the antibody will combine with colloidal gold labeled virus antigen to form a sandwich complex, which will show a positive result.

If the sample contains New Coronavirus IgG antibody, the antibody will bind to colloidal gold labeled New Coronavirus antigen and form a sandwich complex, which will show positive results.

The detection card also contains a quality control line (line C) to judge whether the chromatography process is smooth.

2. What are the sample types for serum antibody detection?

Generally, it is blood, including serum, plasma and whole blood.

3.COVID-19 antibody test in three steps

1. Open the aluminum foil bag of the test card, take out the test card and place it horizontally on the table;

2. Use a pipette to absorb serum/plasma/whole blood sample and add it to the sampling site. Then use the same method to absorb buffer drops and add them to the sampling hole of the test card.

3. Wait 15 minutes and read the result.

4. What are the problems in serum antibody detection?

■ False positive, individual patients with rheumatoid factors in the blood, heterosinophilic antibodies, autoantibodies, drugs and tumor cells, etc., easy to cause cross-reaction test, so occasionally false positive results;

■ False negative, due to the existence of a certain window period of serum antibody detection methods and the sensitivity of the detection kit will appear false negative results.

Therefore, serum antibody test is only used as a supplementary test for suspected cases of novel Coronavirus nucleic acid negative test and cannot be used as a diagnostic indicator for screening alone.

The combined use of serum antibody detection and nucleic acid detection can help to improve the detection rate of the disease and find out the confirmed patients as much as possible, which is more conducive to the control of the epidemic.

Interpretation of results of nucleic acid combined with IgG and IgM antibody detection

COVID-19 Testing antigen detection

A novel coronavirus antigen test can novel coronavirus be detected directly in human body samples. The diagnosis is fast and accurate, with low requirements for equipment and personnel.

antigen test kit_SARS-CoV-2

antigen test kit_SARS-CoV-2

1. Principle of antigen detection kit?

SARS-CoV-2 , N, E and S protein antigens stimulate virus cells to produce specific antibodies.

2. What are the types of antigen test samples?

Usually samples from infected sites, e.g. oropharyngeal swabs, nasopharyngeal swabs, sputum, serum, plasma, etc.

 

3.COVID-19 antigen test in four steps

1. Drop the sample treatment liquid into the sample treatment tube;

2. Stir the sample swab and squeeze the tube wall until the specimen is fully eluted into the treatment solution;

3. Take out the detection card and add sample to the round hole;

4. Wait 15 minutes and read the result.

4. What are the problems in antigen detection?

■ False negative, higher sensitivity of antigen detection is required. Because New Coronavirus mainly affects alveolar and other lower respiratory tract. Therefore, sampling from the upper respiratory tract of nasopharynx and oropharynx cannot determine whether the pathogen can be detected. Or the sample contains a small number of viruses. All these factors may cause missed detection.

■ The preparation process is tedious and time-consuming. The development of the antigen kit requires the preparation of the recombinant antigen first, and then the preparation of monoclonal antibody in mice, which takes about two or three months. If the prepared antibody performance is not good, it needs to be prepared again, which takes another two or three months.

The joint detection

The COVID-19 Testing nucleic acid / antibody / antigen has different focuses and can not be substituted for each other. Multiple detection methods are combined and complement each other. Combine molecular biology and immune level detection to give play to their respective advantages and improve sensitivity and specificity. It can effectively shorten the detection window period, improve the positive detection rate, and provide double guarantee for all possible risk groups.

 

reference：Zhengtu Li，Yongxiang Yi et al. Development and clinical application of a rapid IgM‐IgG combined antibody test for SARS‐CoV‐2 infection diagnosis. J Med Virol.2020；1-7