This still leaves open the nagging question of why studies of natural immunity yield such different results. Anna Wajnberg, a physician at Icahn School of Medicine at Mt. Sinai and co-author of the new, larger study, says it may come down to differences in the subjects studied and the antibody tests used.
Her subjects were people who had gotten Covid-19 and volunteered to donate convalescent plasma after they recovered. That’s an experimental treatment meant to enlist other people’s antibodies to boost immunity in severely ill patients. The researchers used a test method developed by virologist Florian Krammer, which picks out an antibody that’s known to attack the so-called spike protein the virus needs to
get into cells.
What they observed was a small decrease in those with the highest antibody counts, and a slight increase among those with the lowest. That might have happened because some people take longer than others to produce a full immune response to an infection, says Wajnberg. She said it will take time to learn how long immunity lasts over the long term because the disease is so new, but they will keep following the nearly 20,000 people in their study for months to come.
The Chinese study looked only at people who tested positive but developed no symptoms. The weak antibody response measured in those subjects is not surprising since they may have been exposed to such a low viral load that they were able to clear infection without a full immune response.
More troubling are anecdotal reports of people being re-infected, but Wajnberg says this could be an exception to the rule. “With New York a raging epicenter of the pandemic, I would have thought we’d see more people get sick twice between February and April,” if indeed post-infection immunity didn’t work at all, she says.
These contradictory findings can come down to the disproportionate attention that goes to extreme, emotion-inducing messaging, and to the fact that the pace of science related to the pandemic is both frantic and slow. New studies are released by the minute — some careful, some shoddy — but the virus will only give up its secrets over the course of several months. Don’t let your hopes rise and fall on every new finding.
This opinion piece was provided by Bloomberg News.