Antibody levels of Covid-19 patients decline quickly, small study shows

Levels of antibodies in people who have suffered Covid-19 reportedly falls sharply in the two to three months following their infection, a study showed, although the implications for patient immunity were unclear.

According to research published in Nature Medicine during the preceding week, declining levels of antibodies raise concerns about the length of the immune response against the new virus generated by the human body.

If correct, the research might call into question the so-called ‘immunity passports’ being proposed by some and support the prolonged use of public health interventions such as social distancing and isolating high-risk groups, the researchers said.

Countries like Germany had tabled the possibility that that those who have tested positive for antibodies could be allowed to move more freely than those who have not, but this research could stop such proposals in their tracks.

The research, which was conducted at Chongqing Medical University, studied 37 symptomatic Covid-19 patients and 37 asymptomatic patients, and found that 90% of those who had generated antibodies experienced sharp declines in the same over the two-to-three months after infection.

The median percentage decrease was over 70% for both types of patients.

Nonetheless, Jin Dong-Yan, a professor of virology at the University of Hong Kong, who did not participate in the study, said the results do not rule out the possibility that other parts of the immune system might offer protection, Reuters reported.

“The finding in this paper doesn’t mean the sky is falling,” he said, while also noting the small sample of patients that took part in the study.