COVID-19 Antibodies Last Only Months, Calling for Stronger and Longer Lasting Vaccine Protection

People infected with the novel coronavirus could see a decline in their natural immunity to the virus within months, which means that the vaccines currently being developed will have to generate stronger and longer lasting protection, or may have to be given at regular intervals.

A new pre-print paper released on the medical server medrxiv.org but not yet published in a peer-reviewed medical journal suggests that antibody responses could begin declining 20 to 30 days after COVID-19 symptoms begin appearing. The team of UK researchers who wrote the paper also found that the severity of COVID-19 symptoms determined the magnitude of the antibody response. The researchers arrived at their conclusion after examining samples collected from 65 patients with confirmed COVID-19 up to 94 days after they began showing symptoms and from 31 health care workers who took antibody tests every one to two weeks between March and June. "We show that IgM and IgA binding responses decline after 20-30 days," the researchers wrote in their paper. While the study is yet to be peer reviewed, the findings are significant for COVID-19 vaccines currently under development.

"This work confirms that protective antibody responses in those infected with SARS-COV2, the coronavirus that causes COVID-19, appear to wane rapidly. Whilst longer lasting in those with more severe disease, this is still only a matter of months," said Stephen Griffins, associate professor in the University of Leeds School of Medicine, who was not involved in the new study, in a written statement. "Similar short-lived responses are seen against other human coronaviruses that predominantly cause only mild illness, meaning that we can be re-infected as time goes by and outbreaks can adopt seasonality. With the more serious, sometimes fatal, outcomes of SARS-COV2, this is troubling indeed. Vaccines in development will either need to generate stronger and longer lasting protection compared to natural infection, or they may need to be given regularly."

"But this study does reinforce the message that we can't assume someone who has had COVID-19 can't get it again just because they initially became antibody positive," said Dr. Mala Maini, professor of viral immunology and consultant physician at the University College London, who was not involved in the new study, in a statement. "It also means a negative antibody test now can't exclude you having had COVID-19 a few months ago. And it suggests vaccines will need to be better at inducing high levels of longer lasting antibodies than the natural infection or that doses may need to be repeated to maintain immunity."