COVID-19 antibodies may fade quicker than other estimates suggested, according to new research.
Published in Science Immunology, the five-month longitudinal analysis of COVID-19 patients suggested that the IgA and IgM antibodies disappear quickly during recovery though IgG antibodies likely do last longer. Nonetheless, the researchers found that that class of antibodies also declines over time. “The decrease in antibodies after infection also raises the question of how long antibodies elicited by vaccination will last, and whether frequent boosting will be needed to maintain protection,” the researchers said.
The prospect of reinfection with the novel coronavirus that causes COVID-19 has been in the sights of the World Health Organization (WHO) recently. In August this year, Hong Kong reported that it had experienced the world’s first case of coronavirus reinfection. A man who had tested positive for the novel coronavirus – or, to put it in full, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) – four-and-a-half months previously tested positive again. This sparked major concerns about the length of time an individual is immune against the virus after initially being infected and how often COVID-19 antibodies remain to protect one against the virus.
Anecdotal cases of reinfection have been reported since, including in Karnataka state capital Bengaluru. As of October 16th, 24 reinfection cases had been reported worldwide. One individual reinfected died as a result.
“There’s a vast diversity of immune responses as well as responses to infection,” vaccine researcher Dr Dan Barouch of Harvard Medical Research explained, as quoted in BloombergQuint. “Sometimes it’s because of different genetics, and sometimes it’s from a different strain of the virus or other immune parameters, or demographic variables — sometimes it comes down to chance.”
The WHO is taking notice of the prospect of reinfection. “We have seen the number of people infected continue to grow, but we’re also seeing data emerge that protection may not be lifelong, and therefore we may see reinfections begin to occur,” said Dr Mike Ryan, executive director of the WHO’s health emergencies program. “So the question is: what are the levels of protection in society?”
WHO researchers are investigating the length of time COVID antibodies protect one against the virus. “In some people, it may wane after a few months, but we do get a good indication that natural infection immune response is lasting for some months,” said the head of the WHO’s of emerging diseases and zoonosis unit Dr Maria Van Kerkhove. “We’re about a year into this pandemic, and so we still have a lot to learn.”