As a child
Nostalgia is a little stamp
Growing up
Nostalgia is a nucleic acid test report that says “negative”
(Image source: Internet)
Our lives are again shrouded in the shadow of the pandemic
When going out, it is as important as the ID card——
There is also a negative nucleic acid test report
Are you curious:
From where you arrive at the nucleic acid testing site
Then——
Tilt your head up
Get the swab down your throat & nostrils
(Image source: Internet)
What happened in the more than ten hours between getting the nucleic acid test report?
What happened to your throat/nasal swab that was taken? How did your nucleic acid report come about?
Today, we have the fullest reveal.
Everything starts long before you go downstairs to get tested.
First of all, in the selection of the temporary sampling room, the following series of work have been done to ensure safety and accuracy. It is not as simple as “setting up a stall” on the roadside.
Next, sampling.
For you, you just need
“Open your mouth—”
“Tilt your head up a bit—”
Why do cotton swabs either poke the nostrils or the throat?
The nasal cavity and throat are the only way for respiratory secretions to be excreted, so the presence of the new coronavirus can be most found here.
The new coronavirus pneumonia virus is transmitted through droplets or aerosols, mainly infecting the respiratory system of the host. The virus colonizes the respiratory tract and reproduces rapidly. The number of viruses increases sharply and is excreted through respiratory secretions.
Poke the nose to detect the nasopharynx, and poke the throat to detect the oropharynx. Their positions are relatively deep, and there is no difference in essence.
In order to ensure accurate sampling, laboratory personnel need to ensure the standardization of specimen collection.
Whether it is a nasopharyngeal swab or an oropharyngeal swab, there are certain requirements for the depth of collection.
So, when you complain about being stabbed in the throat like crazy—
(Image source: Internet)
It’s not that the staff has a grudge against you.
If it is nasopharyngeal swab sampling, the key points of sampling are: “deep, transfer, and cells.”[2]
“Deep” means halfway from the earlobe to the tip of the nose
“To turn” means to turn 10~15s, about 4~5 turns
“To take cells” means to take cells from the nasopharynx
(Image source: Reference [2])
If it is an oropharyngeal swab, it is also necessary to wipe the bilateral pharyngeal tonsils and posterior pharyngeal wall 3 to 5 times with the swab.
After agile sampling, the staff will immerse the swab tip in 3ml of virus preservation solution (isotonic saline solution, tissue culture solution, cell preservation solution or phosphate buffered saline can also be used) ), discard the tail, and tighten the cap [2].
Just like that, your throat/nasal swab sample will be stored in an airtight container.
Image source: Zhanku Hailuo
The new coronavirus is highly contagious, so the nucleic acid testing staff should also be fully armed to ensure safety.
When collecting samples and before entering the laboratory, be sure to use secondary protection before entering, that is, wear disposable protective clothing, goggles or face shields, double gloves, N95 and above Masks, hats, protective boot covers, etc., so the staff you see doing nucleic acid testing are mostly fully armed.
Heavy protection isolates the virus, but it is also heavy. Even “cold in winter and hot in summer”. Therefore, when the weather is cold and hot, the staff will need a stronger will. (“Dabai” have worked hard! Thank you!)
(Photo source: Chinese government website. On August 4, 2021, at the sampling site of Shuanghe Road Community, Shuangfu Street, Jiangjin District, Chongqing, Zhao Qingyong, a medical staff member of the Third People’s Hospital of Jiangjin District, completed the sampling Two rounds of sampling work, take off the protective clothing and go upstairs [3].)
Staff wearing secondary protective equipment will also spray the outside of the sealed bag with 75% alcohol or disinfectant containing effective chlorine to prevent the surface of the test tube from carrying the virus, and then centrally store it in a dedicated sample transfer Boxes, after layers of packaging, they will be transported to the testing laboratory by a special person and a special vehicle.
Testing does not begin immediately after a sample is escorted to the laboratory. The staff will open the packages one by one and enter the information of each specimen into the system, just like giving each specimen an account.
After entering, each sample has its own unique identity on the Internet, and then its test results will be firmly bound to your health code.
At last the critical sample processing and testing phase has come.
Image source: Zhanku Hailuo
You may have wondered: How do scientists know if you have a virus in your body?
To answer this question, we must first understand a professional detection technology – nucleic acid amplification technology, which can detect the presence of specific gene fragments in the sample. At present, the kits that have been approved for marketing in my country are also based on nucleic acid amplification technology.
If you haven’t given all your high school knowledge back to your teacher, you may remember it.
Every sample must be tested for the nucleic acid of the new coronavirus, and the nucleic acid must first be extracted, which is commonly referred to as a template. After the template and detection reagents are mixed in a certain ratio, they can be tested on the machine.
In the reaction tube, the primers contained in the reagent will bind to the specific gene sequence of the new coronavirus nucleic acid, and continuously copy new nucleic acid fragments under the action of enzymes. Each round of the reaction results in a single copy of a specific nucleic acid fragment, multiplying the number. Each time a specific gene is copied, a fluorescent signal is released.
If a specific gene segment does exist in a sample, it will emit a specific fluorescent signal.
At present, the sites targeted by the new coronavirus nucleic acid detection mainly include 3 conserved gene sequences in the virus genome, namely, the open reading frame 1ab (ORF1ab), the nucleocapsid protein (N) gene and the envelope protein (E) gene as the detection target.
If there is no significant change in the fluorescence signal, then congratulations – the probability is safe [4].
(Image source: Reference [4])
Not necessarily.
This is because the nucleic acid test for the new coronavirus has the possibility of false negatives. Negative results cannot rule out new coronavirus infection, and the reasons for false negatives in each link should be considered.
The currently used nasopharyngeal swabs or throat swabs are mainly tested by qPCR kits, which only have a positive detection rate of 30% to 50%. In order to ensure the rapid screening of large-scale personnel, under the current technology, such false negative results cannot be avoided, so in the epidemic area, the quarantined personnel often need multiple nucleic acid tests [2].
That means getting stabbed in the throat/nose seven or eight times a day. (You have worked hard)
A negative test result doesn’t necessarily mean you’re not infected; and if you test positive, you’re going to be nervous.
At the time of mixed test, it can only be judged that there may be positive specimens in this batch of samples, then another nasal/pharyngeal swab-nucleic acid test will be carried out for the people who are mixed with each other. Determine who the positive infected person is.
In order to prevent possible contamination, the tested samples will also be put into designated medical trash cans for high-pressure destruction.
Congratulations, yin.
Finally, the finishing touches come.
The staff will check the information one by one and upload the test results to the system. It is this step that allows you to easily find the results on the Internet.
“Feminine” – would be the two most pleasing words.
(Image source: Internet)
However, it should be noted that the new coronavirus will continue to change in the human body, and if it is sampled during the suppression period, it cannot be detected.
If you drink water, smoke, drink alcohol, etc. before sampling, it may also interfere with the test results.
So, Even if the result is negative, everyone should always wear a mask when going out, which is not only responsible for themselves, but also for others!
(Image source: Internet)
Recently, many people are sighing with emotion. They didn’t expect that it has been more than 2 years and the epidemic is still affecting our lives.
Do a good job of self-protection at all times, actively vaccinate (remember to do it if you haven’t received a booster shot), and continuously improve our anti-virus ability is the correct solution.
References
[1] Su Zhenjiao, He Jinwen, et al. Nursing Quality Control Evaluation of the Whole Process of Novel Coronavirus Specimen Collection [J], Journal of Gannan Medical College, 2021, 41(11):1101 -1105.
[2] Tong Yongqing, Wang Ming, Xu Wanzhou, et al. Suggestions on clinical laboratory practice for novel coronavirus nucleic acid detection [J] . Chinese Journal of Laboratory Medicine, 2020, 43(3) : 209-212.
[3]http:https://www.gov.cn/xinwen/2021-08/04/content_5629435.htm#8
[4]One article to understand the nucleic acid detection of new coronavirus[EB/OL].http:https://yjj.beijing.gov.cn/yjj/xxcx/kpxc/ylqx6/ 1714959/index.html
Author: Zhang Xiaoyi, Jiang Yongyuan
*The content of this article is for the popularization of health knowledge. It cannot be used as a specific diagnosis and treatment recommendation, nor can it replace the face-to-face consultation of a licensed physician. It is for reference only.
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