The two COVID-19 vaccines that are currently being administered in Spain are mRNA-1273, manufactured by the American biotechnology company Moderna in collaboration with the National Institute of Allergy and Infectious Diseases (NIAID), and COMIRNATY (or BNT162b2 ), manufactured by the alliance between the US pharmaceutical company Pfizer and the German biotechnology company BioNTech. In addition, there are another five pending approval by the European Medicines Agency (EMA) for administration among citizens of the European Union.
The formulation of each one of them is different and is collected in the following table.
Summary of vaccines approved or pending approval by the EMA:
The mechanism of action of any of the vaccines is the generation of a weak and specific immune response against the coronavirus. To do this, they use different formulations that express protein S, which is the protein of the outer envelope of the virus that gives it its characteristic morphology and for which it has received the name of coronavirus (Figure 1).
The interest in the coronavirus protein S is due to the fact that it is the one that triggers the immune response in the body, that is, it is the antigenic (or immunogenic) protein of the virus. Thus, the introduction into the organism of the isolated protein S will trigger the same immune response as the coronavirus but in its absence, and specific IgG memory antibodies against the coronavirus will be generated.
Can I test positive after receiving an RNA vaccine?
Depending on the component of the virus detected by the diagnostic test, and taking into account the formulation of the vaccine, we could obtain a positive result in any of the tests. This would not indicate the presence of viruses in the body, but rather the composition of the vaccine or the immune response against it.
We can classify COVID-19 diagnostic tests into three groups according to which component of the virus it detects:
Types of diagnostic tests for COVID-19
The following figure shows the positivity of the different types of tests over time before a viral infection with SARS-CoV-2 or after the administration of an mRNA vaccine:
Since the positive result of the antigen and antibody tests after vaccination can lead to alarm or uncertainty, it is not recommended to perform them until after 10 days.
The PCR test, on the other hand, cannot be positive for a vaccine because it does not introduce the complete virus genome, but rather a fragment of protein S. There have been cases of vaccinated people who have tested positive for a PCR test; this will be due to the presence of virus in the body by external contagion other than the vaccine.
Why do I have symptoms after vaccination?
Since the mechanism of action of vaccines is the generation of an attenuated immune response, some people may have some symptoms after vaccination.
These symptoms are expected to be more prominent in risk groups with weaker immune systems. However, we could ask ourselves how that person’s symptoms would have been in the face of an infection with SARS-CoV-2 and how severe their symptoms are after the vaccine.
Can I get the coronavirus again while being vaccinated?
The vaccines designed today do not prevent the spread of SARS-CoV-2, but instead produce the generation of IgG memory antibodies that remain in the body for an as yet unknown period of time. In this way, the body is prepared so that, in the event of a second infection, it is moderately or even asymptomatically overcome in a much shorter period of time than in an infection without a vaccine.
The contagion will occur as long as there is a circulating virus. The goal of vaccination is to immunize the population so that we can overcome the viral infection without complications.
In addition, since the infection is fought in a short time, the amount of circulating virus will gradually decrease. This could lead to what is called “group immunity”, in which such a large percentage of the population will be immunized and the amount of existing virus will be so low that the rest of the non-immunized people will be somewhat protected in this way. .
Celia Medrano Rodríguez, Professor and researcher at the International University of La Rioja (UNIR)., UNIR – International University of La Rioja; María del Mar García Suárez, Associate Professor of Microbiology, UNIR – International University of La Rioja and María Dolores Cima Cabal, Academic Coordinator, Microbiology, UNIR – International University of La Rioja
This article was originally published on The Conversation. Read the original.
