Coronavirus antibodies may last only two to three months after infection, study suggests

Coronavirus antibodies may last only two to three months after a person becomes infected with Covid-19, according to a new study published Thursday in Nature Medicine.

Researchers examined 37 asymptomatic people, those who never developed symptoms, in the Wanzhou District of China. They compared their antibody response to that of 37 people with symptoms. The researchers found people without symptoms had a weaker antibody response than those with symptoms.

Within eight weeks, 81% of the asymptomatic people saw a reduction in neutralizing antibodies, compared with 62% of symptomatic patients. Additionally, antibodies fell to undetectable levels in 40% of asymptomatic people, compared with 12.9% of symptomatic people, according to the study’s findings.

Though the study is small, the researchers noted the findings may spur some world leaders to rethink issuing so-called “immunity passports.” Some countries have considered issuing passports or risk-free certificates to people who have antibodies against Covid-19, enabling them to travel or return to work assuming that they are protected against reinfection.

Scientists say they are still learning about key aspects of the virus, including how immune systems respond once a person is exposed. The answers, they say, may have large implications for vaccine development, including how quickly it can be deployed to the public.

One critical question among scientists is whether antibodies produced in response to Covid-19 offer protection against getting infected again. Additionally, scientists are still unsure of how long immunity lasts if antibodies do provide protection.

In general, antibodies that help the body fight off infections are produced in response to invading foreign particles or antigens. Vaccines work by inducing the immune system to produce these molecules. Health officials have said there is not enough data to indicate that coronavirus antibodies ensure immunity against the virus.

Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said earlier this month that a vaccine may not provide long-term immunity if Covid-19 behaves like other coronaviruses.

“When you look at the history of coronaviruses, the common coronaviruses that cause the common cold, the reports in the literature are that the durability of immunity that’s protective ranges from three to six months to almost always less than a year,” he said during an interview on June 2 with JAMA Editor Howard Bauchner. “That’s not a lot of durability and protection.”