A recent study from the United Kingdom found cellular immunity to SARS-CoV-2 remains present in COVID-19 patients for six months after experiencing mild or asymptomatic cases. The research indicates that a level of protection exists for many recovered coronavirus patients.
While researchers labeled the findings as “reassuring,” they were quick to note that in some cases, people may be reinfected with COVID-19. There have been multiple reports of reinfection over the last several months. In many cases, patients reported far worse bouts with the virus the second time around.
One of the study’s authors, Prof. Paul Moss of Britain’s Birmingham University, said the research prompted him to be “cautiously optimistic about the strength and length of immunity generated” after COVID-19 infection. “There is still a lot for us to learn before we have a full understanding of how immunity to COVID-19 works,” he said.
The research has yet to be peer-reviewed, but it was published online on bioRxiv, an “archive and distribution service for unpublished preprints in the life sciences.” The study analyzed the blood of 100 recovered COVID-19 patients six months following their recovery. All patients experienced either mild or asymptomatic cases. Results showed that a key part of the immune system, a patient’s’ T-cell response, remained “robust,” according to Reuters. In some instances, patients’ antibodies levels did drop, however.
“Early results show that T-cell responses may outlast the initial antibody response,” Shamez Ladhani, co-author of the study and consultant epidemiologist at Public Health England, said. There was also variation in the size of T-cell response. It was typically “considerably higher” in those who experienced symptoms, as opposed to those with asymptomatic cases.
The results can be interpreted in one of two ways, according to researchers. It is possible that people who experienced mild symptoms gain higher cellular immunity or that asymptomatic patients are merely more equipped to fight off the virus, requiring a less immune response from their bodies.
The research “bodes well for the long term,” according to Eleanor Riley, an immunology and infectious disease professor at Edinburgh University. She did note, however, that “we don’t yet know whether the people in this study are protected from re-infection.”
The study has reignited the debate about whether mild infection can grant lasting immunity to the virus. It is also leading into conversations about an eventual vaccine. “If natural infection with the virus can elicit a robust T-cell response then this may mean that a vaccine could do the same,” Prof. Fiona Watt, executive chair of the U.K.’s Medical Research Council, said.
Thus far in the pandemic, more than 48.8 million cases have been reported worldwide. In the U.S., more than 9 million people have contracted COVID-19. More than 1.2 million lives have been lost, globally, to the pandemic with 232,638 of these deaths occuring in the U.S.