Are we immune after recovering from SARS-CoV-2? This question, crucial in efforts to combat the disease and its spread, has yet to get a clear-cut answer. A team of researchers from Boston's Brigham and Women's Hospital set out to investigate and found that some covid-19 patients who quickly recovered from the disease may have developed a stronger and more durable immune response towards the virus.
While many scientific studies have set out to look for covid-19 antibodies after contamination, to this day, we don't really know with any certainty for how long a former patient remains immune. Some European and American research agree on a period of immune response lasting around four months, but outcomes seem to vary according to whether patients developed severe or mild symptoms.
A new study by Brigham and Women's Hospital researchers and published in Cell identified patients who had quickly recovered from the disease while producing a persistent antibody response.
The team recruited 92 people who had recovered from symptomatic covid-19 between March and June 2020 in the Boston region. Five patients were treated in hospital while the others recovered at home. The team collected and analyzed their blood samples every month to determine the presence of antibodies in immunoglobulins-G (IgG) -- crucial to long-term immunity -- against the virus that causes covid-19. The participants were divided into two groups, the first one made up of patients who had maintained good levels of IgG specific to the virus during several weeks, and the second group made up of patients whose antibodies decreased or even disappeared.
The researchers observed an important decrease of IgG levels after three or four months for most patients (in keeping with previous research), however, they also noted that the production of antibodies remained stable, and sometimes increased, during the same period for about 20% of participants. An important detail is that the 20% had shown symptoms during a shorter period than patients who recorded antibody decline (about 10 days in average, against 16 days).
Researchers warned that these results should be interpreted cautiously since most participants were adult white women. The team will have to validate these results with a wider sample of people more representative of the population as a whole to show persistent immunity.