Previous infection with Covid-19 does not necessarily protect against coronavirus in the longer term, especially when caused by new covid variants of concern, a study on healthcare workers suggests.
Oxford University researchers found marked differences in the immune responses of medical staff who contracted Covid, with some appearing far better equipped than others to combat coronavirus six months later.
Scientists, on the study conducted with the United Kingdom Coronavirus Immunology Consortium, said the results reinforced the importance of everyone getting vaccinated by the covid vaccine regardless of whether they had been infected with the coronavirus virus earlier in the Covid-19 pandemic.
“If you look at the trajectory of the immune response after getting infected by the virus, mostly it is still detectable six months later, but it is highly variable between people,” said Eleanor Barnes, a professor of hepatology and experimental medicine at Oxford and a senior author on the study.
“That is quite different to vaccination. If you vaccinate, you get a really robust immune response, but with natural infection, there is much more diversity in responses.”
The researchers analyzed blood samples from 78 healthcare workers who had been infected with Covid, with or without symptoms, between April and June last year. The blood sample was checked monthly for up to six months post-covid for a range of immune responses. These included different types of antibodies that target the coronavirus, B cells that make antibodies and retain a memory of the disease, and T cells, which reduce the severity of the coronavirus disease by killing off infected cells.