In a potentially huge blow to the global pursuit of developing an effective COVID-19 cure, researchers in London say that antibodies in patients who have become infected by the virus may decline, or even disappear, within months, suggesting immunity from an eventual vaccine could fade as well over time.
The study, which has yet to be peer-reviewed, was conducted by a group of researchers at King’s College London on 96 patients and healthcare workers in London hospitals who had previously tested positive for the virus.
Nonetheless, a group of established researchers polled by the U.K.’s Science Media Centre described the research as robust, forming an early indication that COVID-19 has the potential to be a recurring, seasonal virus—much like the common flu bug—likely complicating efforts to completely eradicate the virus.
“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,” said Stephen Griffin, an associate professor in the School of Medicine at the University of Leeds. “With the more serious, sometimes fatal, outcomes of SARS-COV2, this is troubling indeed.”
The study found that antibodies in the patients swiftly declined in the weeks and months after symptoms first appeared. The antibodies were most significant in patients who had a more severe response to the virus.
Only 17% of the 60% of patients who had had a particularly strong antibody response when they were fighting the virus still had those those antibodies at the same levels three months later. In some cases, the antibodies disappeared entirely, the researchers found.
The study, if backed up by further evidence, would further undermine the concept of “herd immunity”—or the idea that when enough of the population becomes immune to a virus through exposure, even society’s most vulnerable are protected—as effective, while putting to bed the idea of “immunity passports” for the previously infected. It also raises the prospect that any effective vaccine will require more than one shot, but may instead need to be regularly administered to remain effective.
“Antibody testing for COVID 19 has been seen by many as a psychological balm against the concerns of a possible infection,” said James Gill, an honorary clinical lecturer at Warwick Medical School. However, this study undermined the idea that for those with antibodies, life could go back to normal, he said.
“Even those with a positive antibody test, especially those who cannot account for where they may have been exposed, should continue to use caution, social distancing and appropriate mask use.”
However, several experts noted that hopes to build immunity to the virus are not entirely reliant on antibodies, but also on other immune responses, which may potentially help fight the virus during future infections, if not protect from it completely.
“Even if you’re left with no detectable circulating antibodies, that doesn’t necessarily mean you have no protective immunity because you likely have memory immune cells (B and T cells) that can rapidly kick into action to start up a new immune response if you re-encounter the virus. So you might well get a milder infection,” said Mala Maini, a professor of viral immunology and a consultant physician at UCL.
“We know from SARS infection (SARS-CoV-1) that T cells persisted many years longer than antibodies,” she said.
Now, researchers need to determine whether that will also be the case after a patient contracts COVID-19.