The human body's immunity to Covid-19 appears to gather strength with more time between vaccination and infection, a new study has shown. According to US-based Oregon Health & Science University (OHSU) study, it suggests people, who have had Covid-19, have benefited from vaccination, even if they delayed it. In this study, researchers measured the immune response in blood samples for people, who gained hybrid immunity by either getting vaccinated before a breakthrough infection or by getting vaccinated after contracting Covid-19.
The researchers measured the immune response in 96 generally healthy employees and found that it was uniformly stronger the longer the time period between vaccination and infection. The longest interval measured was 404 days. Their findings suggest that vaccine boosters should be spaced no more frequently than a year apart, at least among healthy people, said study.
"Longer intervals between natural infection and vaccination appear to strengthen immune response for otherwise healthy people," said co-senior author Fikadu Tafesse, PhD, associate professor at OHSU School of Medicine. Moreover, their findings indicate that the magnitude, potency, and breadth of the hybrid immune response all increased with the length of time between virus exposure - whether through vaccination or natural infection.
"The immune system is learning. If you're going to amplify a response, what this study tells us is that you might want to boost that response after a longer period of learning rather than early after exposure," said co-senior author Marcel Curlin, MD, associate professor of medicine (infectious diseases) at OHSU School of Medicine.
Further, the researchers found that developing hybrid immunity was no different if someone was vaccinated after contracting Covid-19 or after contracting the disease after vaccination. Both groups developed an equally potent immune response.
In this study, the scientists suggest that so-called memory cells, which produce antibodies to neutralise viruses and their variants, are long-lasting. Even those who've delayed vaccination due to the SARS-CoV-2 virus stand to benefit from vaccination, according to the authors.