A new French study showed that almost the entire group of caregivers who were only slightly affected by the coronavirus developed protective antibodies that were still present 28 days after the onset of symptoms. How will this immunity persist in the long term?
A “large majority” of patients who suffered from a mild form of Covid-19 developed antibodies that could immunize them against the disease for several weeks. This is the result of a study by Strasbourg University Hospital and the Pasteur Institute, which is described in detail on the MedRxiv website.
These results are “encouraging” in the sense that little is known about the mechanisms of immunity to the new coronavirus, particularly in people with mild forms of the disease. “People with severe disease are known to develop antibodies within 15 days of the onset of signs. We now know that this also applies to people with milder forms of the disease, although antibody levels are likely to be lower,” said study author Arnaud Fontanet, head of the department of global health at the Pasteur Institute in a news release.
“Our study shows that in most cases, antibody levels are enough to protect against a new Sars-CoV-2 infection, at least until 40 days after the signs appear,” added Olivier Schwartz, head of Pasteur’s Virus and Immunity Department. According to him, “the objective now is to evaluate the long-term persistence of the antibody response and its ability to neutralize the virus.”
Good news for the development of a future vaccine
The study, whose results were published on May 22 and reported in a Pasteur institute press release on May 26, was carried out on 160 hospital staff members from the two medical centers of Strasbourg’s University Hospitals. They all suffered from mild forms of Covid-19.
Serological tests (aimed at subsequently detecting signs of past infection) showed that almost all of these people (153 or 159 of 160, depending on the type of test used) developed antibodies within 15 days of the start of the infection. Another test was used to determine if these antibodies had the ability to neutralize the virus. Conclusion: 28 days after the onset of symptoms, 98% of patients had developed these neutralizing antibodies.
“These results are also good news for future vaccination strategies,” said Professor Samira Fafi-Kremer, head of the virology department at Strasbourg University Hospital and first author of the study, which is also cited in the press release.