A small but crucial study in the UK found that “cellular immunity” to the SARS-CoV-2 virus was present in patients with COVID-19 mild or asymptomatic disease after six months – suggesting they may have some protection at least for that time. The scientists presented the findings from 100 non-hospitalized COVID-19 patients in the UK, which they said were “welcome” but did not mean that it was unlikely that people would be able to contract the disease twice in rare cases.
“While our findings give us cautious optimism about the strength and length of immunity produced after SARS-CoV-2 infection, this is only part of the puzzle,” said Paul Moss, a professor of hematology at the University of Birmingham who co-led the study. “We have a lot to learn before we fully understand how COVID-19’s immunity works.”
Experts who were not directly involved in the study said the findings were important and would increase knowledge of the potential protective immunity of COVID-19.
The study, which has not been peer-reviewed by other experts but has been published online on bioRxiv, analyzed the blood of 100 patients with COVID-19 mild or asymptomatic conditions for six months of recovery. It found that although antibody levels dropped in some patients, their T-cell response — another key part of the immune system — remained strong.
” (Our) early results suggest that the T-cell response may be longer lasting than the initial antibody response,” said Shame Ladhani, an epidemiologist at Public Health England who co-led the work. The study also found that T-cells responded differently, with patients with symptoms responding more strongly than those with no symptoms.
This can be explained in two ways, the researchers said. It is possible that higher cellular immunity may give better protection against re-infection in people with symptoms, or that patients who are equally asymptomatic are better able to fight the virus without the need to produce a large immune response.
“These results provide assurance that while the antibody titration of SARS-CoV-2 will drop below detectable levels within a few months of infection, immunity to the virus may remain to a certain extent,” said Charles Bangham, chairman of immunology at Imperial College London.
“It’s … This bodes well in the long run, both for vaccine development and for the long-term prevention of the possibility of re-infection,” said Eleanor Riley, professor of immunology and infectious diseases at the University of Edinburgh. But she stressed, “We don’t yet know if the people in this study will be protected from re-infection.” “