(CTN News) – Researchers claim that if you had a Covid infection before vaccination, you might have less immunity. Stanford University researchers found that, compared with people without prior SARS-CoV-2 infection, the magnitude and quality of an immune cell response to two doses of the Pfizer-BioNTech Covid-19 vaccine was significantly lower in people with prior SARS-CoV-2 infection.
Vaccinated people who had never had Covid-19 had a significantly higher level of this critical immune cell that targets SARS-CoV-2 spike protein than unvaccinated people who had never had Covid-19. You might have been less infected with Covid if you had it before taking vaccination.
Vaccinating after recovering from SARS-CoV-2 infection provides better protection than not vaccinating.
Immunity published these findings, suggesting that the virus damages an important immune-cell response.
Using a very sensitive tool, Stanford microbiology and immunology professor Mark M. Davis and his colleagues examined how immune cells called CD4+ and CD8+ T cells respond to SARSCoV-2 vaccination and infection.
In order to prevent Covid from spreading, these cells coordinate the immune system’s response to the virus and kill infected cells. This tool can be used to target several dozens of specific regions of the virus’ spike protein and other viral regions as well.
Parts of the SARS-CoV-2 spike protein are used in the Pfizer-BioNTech vaccine in order to elicit an immune response without causing infection.
Blood samples from three groups of volunteers were analyzed for CD4+ and CD8+ T-cell responses. In one group, two doses of the Pfizer-BioNTech Covid-19 vaccine were given to people who had never been infected with SARS-CoV-2.
In the second group, two doses of the vaccine were administered after previous infection with SARS-CoV-2. Covid-19 was found in the third group, which was unvaccinated.
The researchers found that vaccination of people who had never been infected with SARS-CoV-2 induced robust responses from CD4+ and CD8+ T cells. In addition, these T cells produced cytokines, which recruited other immune cells, such as antibodies-producing B cells, to fight pathogens.
Prior to vaccination, people who had been infected with SARS-CoV-2 produced spike-specific CD8+ T cells at considerably lower levels – and with less functionality – than those who had never been infected.
Further, unvaccinated people with Covid had significantly lower levels of spike-specific CD8+ T cells than vaccinated individuals without Covid infection.
These findings suggest that SARS-CoV-2 infection damages the CD8+ T cell response, similar to the effect seen in earlier studies showing long-term immune system damage related to hepatitis C or HIV infection.
Researchers note that vaccine strategies should be developed to boost antiviral CD8+ T cell responses specifically in those who were previously infected with SARSCoV-2.
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