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Author: Wang Shengsheng
Source: Medical Pulse Breathing Channel
This article is published by the author with the authorization of Medical Pulse, please do not reprint it without authorization.
This afternoon, a colleague in my WeChat exchange group asked: Is it reasonable that we cannot do nucleic acids within 24 hours after the new crown vaccine?
In fact, the CDC and experts in many provinces and cities across the country have reminded this that the nucleic acid test within 24 hours of receiving the new crown vaccine may have false positive results, so it is recommended that after receiving the new crown virus vaccine, if nucleic acid testing is needed, it should be taken 24 hours after leaving the vaccination unit (in some areas, it is stipulated that it is 48 hours).
Why is it possible to have a false positive nucleic acid within 24 hours of receiving the COVID-19 vaccine? On this issue, CDC experts believe that the reasons for this are:
The new crown virus inactivated vaccine is prepared by the wild virus through culture, inactivation and other processes, although the virus has lost its infectivity and pathogenicity, but still retains a relatively complete viral nucleic acid fragment.
During the vaccination process, opening the vaccine bottle, extracting the vaccine liquid, exhausting the syringe, residual liquid in the syringe or vaccine bottle after vaccination, etc., may contaminate the surface of the vaccination table, walls, door handles, corridors, clothing of the vaccinator and recipients in a liquid or aerosol manner.
Due to the extremely high sensitivity of polymerase chain reaction (PCR) detection, if the nucleic acid fragment is sampled before it is degraded, it is likely that the nucleic acid test result will be positive.
There are real examples of nucleic acid false positives caused by the above reasons, such as the Qianjiang City Novel Coronavirus Pneumonia Epidemic Prevention and Control Headquarters released such a message in the middle of this year:
At 22:00 on June 3, 2021, when the city conducted nucleic acid screening for the new coronavirus for returnees in key areas, it was found that the nucleic acid test results of 4 returnees were weakly positive. The city immediately launched an emergency response, implemented closed management and full nucleic acid screening in its living area. On the morning of the 4th, the provincial expert group rushed to our city to guide the disposal, and 4 people were sampled for 3 consecutive times, the nucleic acid test results were negative, 4 people had no symptoms related to new crown pneumonia, the serum antibody was negative, and the chest CT and blood routine tests were normal. Nucleic acid tests were conducted on 309 residents of the 4 people's place of residence, and the results were negative, and 115 environmental samples of the places involved in the activities of the 4 people were collected, and the results were negative.
After epidemiological investigation and laboratory testing, the working environment of the medical staff sampled for 4 people and the sample transfer box were tested positive for nucleic acid. The expert group judged that the weak positive nucleic acid test of 4 people was caused by the spillover of the vaccine when the medical staff carried out the new crown virus vaccination, and it was not contagious.
In other words, although the inactivated virus of the new crown vaccine has lost its infectivity and pathogenicity, it still retains a relatively complete viral nucleic acid fragment, because during the opening of the vaccine bottle and related operations, the inactivated virus may contaminate the environment of the inoculation area in a liquid or aerosol manner, and people can enter the area to contaminate their hands and clothing.
Seeing this, do you understand why the COVID-19 vaccine may have a false positive for nucleic acid?
In fact, the experts' statement is very scientific, but have you found a problem?
The above statement of the expert can only explain the working environment of vaccination, and the reason why the hands and clothes of people who enter the environment may be positive for nucleic acid, and does not seem to explain why the throat swab made after the person leaves the vaccination environment is positive for nucleic acid - the throat swab is a specimen taken from the human pharynx, not from the human hand or clothing, and it is reasonable to say that it should not be positive - in this regard, the author guesses that this is because the inactivated virus not only pollutes the surface of environmental objects. It is also possible to contaminate the air in the form of an aerosol that allows people to inhale the airways and be detected in the pharynx, or to be inhaled when touching the nose or mouth after the hands are contaminated.
So, could it be that the inactivated COVID-19 vaccine directly leads to human infection, resulting in a throat swab with positive nucleic acid?
Non-inactivated vaccines have this possibility, but inactivated vaccines will not, which is the reason why China's vaccines are the safest and most reassuring in the world.
Inactivated vaccine in the production process has completely lost the virus inactivity and killed, the virus has completely lost its infectivity and replication ability, so after vaccination will not make people infected with diseases, but also can stimulate the human body to produce corresponding antibodies to resist the virus invasion, with the international standard of safety and efficacy evaluation, therefore, people will not be vaccinated with the new crown inactivated vaccine and directly lead to positive nucleic acid test.
In summary, in order to reduce the interference of false positive results caused by the new crown vaccination on the epidemic prevention and control order, when the new crown virus vaccination, masks should be worn throughout the whole process, try not to bring personal belongings into the vaccination work area, do not stay in the vaccination work area for too long, do not directly touch objects in the vaccination work area (such as desktops, walls, door handles, etc.), do not touch the nose and mouth with your hands, and pay attention to washing your hands, washing your face and changing clothes in time.