‘COVID-19 antibodies appear to last for at least two months’

ISLAMABAD: COVID-19 patients have been found to carry antibodies to the coronavirus for almost two months after falling sick, in a preliminary study. However, it is unclear whether the antibodies could protect the patients from being re-infected.

Scientists looked at the blood samples of 177 people who had caught the coronavirus which causes COVID-19. They found most patients had antibodies that were detectable for up to around 60 days after they were infected by the coronavirus. But between 2 to 8.5 percent did not.

The findings were submitted as a pre-print to the website medRxiv, meaning the study hasn't been through the rigorous peer review process required to publish in scientific journals. Releasing studies this way enables scientists to spark debate on a topic, reported foreign media. The group of participants included a range of COVID-19 patients, with 19 percent not showing symptoms when they tested positive, but were diagnosed when they were being treated for other conditions. A total of 94 percent of the patients were hospitalised with COVID-19, a quarter whom died. Some 73 percent of patients had at least one underlying health condition, which is known to be a risk factor for complications. In past studies, antibodies have been linked to more serious infections. The authors of the new paper found those who did have antibodies were more likely to have COVID-19 symptoms, be older (at 65 versus 41 years old, on average) and were more likely to have at least one underlying health condition—such as high blood pressure—as well as a higher body mass index (BMI). High blood pressure and obesity are known to be risk factors for more severe COVID-19.

Patients who had antibody responses were also more likely to have markers of inflammation in the body. This process in turn is linked with an overreaction of certain immune cells that are thought to raise a person's risk of dying of COVID-19.

What the team described as "non-white" people had a higher chance of having more antibodies and being ill enough to be hospitalised, the team found. This finding mirrored past research suggesting that higher antibody levels are linked with disease severity, and that people of black and ethnic minority backgrounds are more likely to die of COVID-19.

The authors acknowledged their study was limited for a number of reasons, including that most of the patients were hospitalised. More research is needed to document antibody levels in patients with less severe infections, they said.

Co-author Professor Sanjeev Krishna at the St George's, University of London in the UK, said in a statement: "Our results provide an improved understanding of how best to use viral and antibody tests for coronavirus, especially when not every person exposed to the virus will have a positive response."

Daniel M. Davis, professor of immunology at the University of Manchester who did not work on the paper, told Newsweek: "Understanding how antibody production varies among people is vital for many reasons, not least in learning how to treat people appropriately."