This article is part of the column of Rumor Detector, click here for other texts.
The origin of the rumor
There are rumors on social media that an unknown number of people have tested positive for COVID-19 after being vaccinated. These rumors often have for starting point a authentic story, but the story finds itself shared and amplified by those who see it as confirmation of their worst fears against the vaccine. For example, a Quebec video shared on Facebook in mid-May and viewed 95,000 times, asserts that the vaccine is a “deadly virus” injected to contaminate the unvaccinated and perpetrate a “global genocide”.
The vaccine does not immediately protect
It must first be remembered that in a campaign where hundreds of millions of people have already been vaccinated, it is statistically inevitable that there will be a number of people who had unknowingly caught COVID one day. or two before they got their vaccine, so they only tested positive after the vaccine.
In addition, since the vaccine takes two to three weeks to be fully effective, it is just as inevitable that a certain percentage of those vaccinated may be infected a few days after vaccination: for example, a person may have had a false sense of security and released barrier gestures. Or else she was just unlucky.
Protection is not perfect
It should also be remembered that protection is at its highest after the second dose for all vaccines available in Canada (AstraZeneca, Pfizer and Moderna).
But even after the second dose, COVID-19 vaccines, like all vaccines, are not not 100% effective. This is why the distancing measures continue to be in place until a certain collective immunity has been achieved.
Finally, among the arguments sometimes put forward, there is the phenomenon called “Facilitation of infection by antibodies” (Antibody-dependent enhancement). This is a rare phenomenon, consisting, as the name suggests, in antibodies which, instead of countering certain viruses, facilitate their entry. We did not observe it in clinical trials of vaccines against this coronavirus, nor in vaccinees.
The vaccine does not cause a positive PCR test
In addition, PCR tests, which have been the target of other rumors for months as to their reliability, find themselves included in these post-vaccination screening stories. Remember that PCR tests are used to detect part of the genetic material of the virus. Therefore, would it be possible that the vaccine could fool these tests?
Thereupon, the cause seems heard: the vaccine can’t make a positive PCR test. Certainly, RNA vaccines also contain parts of genetic material, but only fragments – strands of messenger RNA.
On the other hand, since the function of the vaccine is to activate the immune system, in this case to activate the production of the appropriate antibodies, another type of test, called a serological test, which is used to determine whether the person has been infected with the virus in the past, may test positive. The serological test, in fact, will detect the antibodies created for the sole purpose of fighting the virus, if it occurs in the future.
Photo: Ali Raza / PxHere
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