Covid-19 immunity seems gain strength the longer the time elapsed between vaccination and infection. The information, according to a team of researchers from the University of Medicine and Sciences in Oregon (USA), has implications for vaccination protocol recommendations as the pandemic transitions to an endemic state.
The research published on the “medRxiv” website evaluated the antibody response in blood samples from a group of people who had obtained the so-called “hybrid immunity” through two means: vaccination followed by a breakthrough infection -which occurs when someone who is fully vaccinated (14 days after the last dose of the vaccine) tests positive for the virus- or vaccination after past infection by Covid-19.
After evaluating the immune response in blood samples from 96 largely healthy university center employees, the researchers found that the immune response was consistently stronger the longer the time period between vaccination and infection. The longest interval measured was 404 days. “Longer intervals between natural infection and vaccination appear to strengthen the immune response of healthy people,” notes co-lead author Fikadu Tafesse.
The new research is the latest in a series of laboratory discoveries by scientists at this center that reveal a pattern of enhanced immune response through hybrid immunity.
Thus, a recent study published in “The Lancet Infectious Diseases” showed that protection against severe disease and hospitalization remains high 12 months after developing hybrid immunity: people with this type of immunity had at least 95% less chances of having severe covid or needing hospitalization.
We think, says researcher Marcel Curlin, that this scenario is probably related to the maturation of the body’s immune response over time.
Relying on natural infection alone is a bad idea
“The immune system is learning,” Curlin explains. So, to enhance a response, what this study tells us is that it may be better to allow more time between infection and vaccination so that the immune system can learn better.”
Furthermore, the study finds that it did not matter whether someone developed hybrid immunity by getting vaccinated after contracting Covid-19 or vaccinated after an infection. Both groups developed an equally potent immune response.
Findings suggest long-lasting power of calls memory cellsthe B cells that recognize a virus and generate antibodies to neutralize the virus and its many variants.
These findings are the latest to signal that the virus is evolving towards an endemic state.
The authors write that a growing group of people who have contracted the SARS-CoV-2 virus will benefit from vaccination, even if they have delayed it until now.
Relying only on natural infection is a bad idea, “given the risks of severe disease, long-term complications, and death,” the authors write.
The researchers say the findings are the latest to signal that the virus is evolving towards an endemic state.
«Our results point to a future in which vaccine advances are expected to help build a population-level reservoir of immunity that can help mitigate future waves and reduce the opportunity for further viral evolution.», they write.
The researchers cautioned that the immune response was measured in relatively healthy people, and that booster vaccinations may be recommended more frequently among vulnerable people who are older or immunocompromised.