Many patients who have recovered from Covid-19 may lose their immunity to the disease within months, according to research from scientists at King's College London, which, if proven true, will have wide implications for vaccine development and could put a "nail in the coffin" in the idea that herd immunity to the coronavirus is attainable.
- Researchers at King's College repeatedly tested 96 patients between March and June, all of whom were confirmed to have had Covid-19 via a PCR test or a positive antibody test.
- According to the research, which has not yet been peer-reviewed, the level of antibodies capable of combating the coronavirus peaked about three weeks after the onset of symptoms but quickly declined.
- Roughly 60% of patients tested produced "potent" antibodies while battling the coronavirus, but just 16.7% had the same level of potency detectable a mere 65 days later.
- The magnitude of the antibody response depended on the disease's severity, with antibody levels both higher and longer-lasting in more severe cases.
- For some milder cases, antibodies became undetectable after approximately 50 days, "highlighting the transient nature of the [antibody] response towards SARS-CoV-2 in some individuals."
It's important to note that this is a longitudinal study that has not been peer-reviewed. If it turns out to be supported by other research, the ramifications on the durability of vaccine protection would be substantial. Most significantly, it would mean that herd immunity to the coronavirus is likely unachievable. Many scientists have previously predicted individuals may be susceptible to being infected by Covid-19 repeatedly because short-term immunity and reinfection has been observed in other human coronaviruses. Earlier this month, a study by leading Spanish epidemiologists published by the medical journal The Lancet found that just 14% of individuals who had tested positive for coronavirus antibodies in an initial round of testing tested positive for antibodies in subsequent tests carried out weeks later. The King's College study "puts another nail in the coffin of the dangerous concept of herd immunity," said professor Jonathan Heeney, a virologist at the University of Cambridge.
12,913,000: The coronavirus has infected more than 12,913,000 people worldwide as of Monday morning, according to the New York Times, leading to at least 569,100 fatalities.
"The good news is that the SARS-CoV-2 virus appears to make fewer errors when it reproduces than influenza viruses. Perhaps this will allow us to maintain our immunity for longer. Even that may be good enough to make the disease less severe on a second exposure." - Dr. Mark Kortepeter.
According to MIT Technology Review, "antibodies are not the only way people can fight off Covid-19. T cells, which seek and destroy cells infected with SARS-CoV-2, could also provide some protection." It adds that "we have not yet generated enough data from patients to be able to draw conclusions on immunity with a high degree of certainty. There have been anecdotal reports of people catching Covid-19 for a second time, but none have been confirmed."