More than six months since the emergence of the coronavirus, experts have been exploring one key question: how long is the body protected from COVID-19 after infection and recovery?
Researchers hoped that the coronavirus would trigger the development of long-lasting antibodies to stop secondary cases of COVID-19 in the future. However, results from a Chinese study reveal that the length of immunity may not be nearly as long as once believed.
What Are COVID-19 Antibodies?
The body naturally creates antibodies to fight infections. Every winter, for example, the human body develops antibodies to attempt to fight the flu. As soon as antibodies recognize a foreign substance, they stop it from causing harm. This process of recognizing and eliminating foreign invaders makes antibodies essential to a strong immune system.
Scientists and researchers are extremely interested in the unique properties of the antibodies created in the presence of the coronavirus. By understanding how long those antibodies remain active in the body, researchers can develop reliable COVID-19 treatments and diagnostic tools. They can also predict the future behavior of COVID-19 infections.
What Does New Chinese Research Reveal About Antibodies?
A Chinese study recently reported that levels of an antibody correlated to COVID-19 fell sharply only two to three months after infection. This pattern was observed in symptomatic and asymptomatic patients alike.
These disappointing results have experts questioning the length and efficiency of immunity against the coronavirus.
According to the research published on June 16, 1,500 coronavirus patients in Wuhan, China were screened for antibodies. Researchers compared their antibody levels to those of three other groups:
- 20,000 members of the general population
- 1,600 patients hospitalized for reasons other than COVID-19
- 3,800 medical workers who were “inevitably” exposed to the virus in its early days and presumably had developed antibodies.
They found that nearly 90% of COVID-19 patients tested positive for virus antibodies, compared to 1-5% of people in the other three groups. Based on the 10% of COVID-19 patients who tested negative for antibodies, as well as the majority of healthcare workers who lacked antibodies, researchers theorized that “after SARS-CoV-2 infection, people are unlikely to produce long-lasting protective antibodies against this virus.”
A similar study was published two days later. It reported that asymptomatic individuals reacted less to infection, with 40% of asymptomatic volunteers showing undetectable levels of protective antibodies in two to three months after infection.
Doctors and experts reacted to these two Chinese studies. “Overall, these results are interesting and provocative but more research is needed, following large numbers of people over time,” said Daniel Davis, an immunologist at the University of Manchester. “Only then will we clearly know how many people produce antibodies when infected with coronavirus, and for how long.”
NIAID director Anthony Fauci stated that he has observed the same patterns himself. When speaking with the Journal of the American Medical Association in June, Fauci noted that individuals do not have “a uniformly robust antibody response,” which is why it’s difficult to develop a vaccine that works equally well for all recipients.
The bottom line? As explained by Akiko Iwasaki, a viral immunologist at Yale University, “These reports highlight the need to develop strong vaccines, because immunity that develops naturally during infection is suboptimal and short-lived in most people. We cannot rely on natural infection to achieve herd immunity.”
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