Individuals who contracted Covid-19 prior to taking vaccine may have lower immunity
The researchers found that individuals who had never been infected with SARS-CoV-2 and received the Pfizer-BioNTech Covid-19 vaccine had a strong immune response to the virus' spike protein.
A study conducted by researchers at Stanford University in the US suggests that individuals who had contracted Covid-19 prior to being vaccinated may have lower immunity. The study found that the response of a key immune cell to the Pfizer-BioNTech Covid-19 vaccine was lower in individuals who had previously contracted the virus compared to those who had not.
Led by Mark M. Davis, Professor of microbiology and immunology at Stanford’s School of Medicine, the researchers designed a very sensitive tool to analyse how immune cells called CD4+ T cells and CD8+ T cells respond to SARS-CoV-2 infection and vaccination.
Unvaccinated individuals who had contracted Covid-19 had lower levels of this key immune cell than vaccinated individuals who had not been infected. The study also found that individuals who had recovered from Covid-19 and then received the vaccine were more protected than those who had not been vaccinated.
The study was published in the journal Immunity and led by Professor Mark M. Davis of Stanford’s School of Medicine. The researchers designed a tool to analyze how immune cells respond to SARS-CoV-2 infection and vaccination. The tool was used to study CD4+ and CD8+ T-cell responses in blood samples from three groups of volunteers.
The tool was designed to identify T cells that target any of dozens of specific regions on the virus’s spike protein as well as some other viral regions. The Pfizer-BioNTech vaccine uses parts of the SARS-CoV-2 spike protein to elicit an immune response without causing infection.
The researchers found that individuals who had never been infected with SARS-CoV-2 and received the Pfizer-BioNTech Covid-19 vaccine had a strong immune response to the virus’ spike protein. However, individuals who had been infected with SARS-CoV-2 prior to vaccination had lower levels of spike-specific CD8+ T cells. The study highlights the need to develop vaccination strategies that boost antiviral CD8+ T cell responses in individuals who have previously been infected with SARS-CoV-2.
