Vaccinated Israelis who contract the coronavirus feel it more moderately but can still suffer from the so-called “long COVID” in significant numbers, suggests a study released Wednesday.
Sheba Medical Center monitored 1,497 fully immunized health workers after receiving their second injection.
His new findings on 39 “breakthrough” infections among health workers contracted within three months of their second injection were published in the New England Journal of Medicine.
“We mainly found a very mild infection,” senior author, director of Sheba’s infectious disease epidemiology unit Gili Regev-Yochay, said at a press briefing on Wednesday. She stressed that she considers the number of breakthrough infections to be low, highlighting the high effectiveness of the vaccine.
“About 33% were totally symptomatic, then 10% had very mild, negligible disease with just a runny nose or something. Only 4% of people had a fever, so overall it was very mild. “
“But I have to say that almost 20% had persistent symptoms for more than 6 weeks, which we call ‘long COVID.’ Some had a loss of taste or smell, others had severe fatigue, a few – some have not been able to return to work after six weeks, which I would say raises concerns, ”said Regev-Yochay.
Regev-Yochay noted that the research preceded the arrival of the now dominant Delta variant in Israel, but argued that the results are still relevant in highlighting general trends among vaccinated populations.
Another piece of research can help policymakers solve the conundrum of whether and when to start widely distributing third doses of the vaccine, and which demographics should be prioritized if necessary.
Doctors are unsure whether antibody levels are a clear indicator of the risk of reinfection, because other aspects of the immune response may be more important. But Sheba research suggests a strong correlation between antibodies and vulnerability to infection.
“People who [were] infected had, on average, three times less neutralizing antibodies just before being infected than the others, ”said Regev. “What if we watch rush hour when the headlines [antibody concentrations] were the highest, their titers were seven times lower than those who had not been infected.
She suggested that serologic testing to determine antibody levels among different demographics will help authorities assess who needs boosters and when.
Regev said his research also indicates that antibody levels are a good indicator of the chances that a vaccinated individual who subsequently contracts the coronavirus will infect others.
“The correlation was very strong there, so people who had higher neutralizing antibodies had higher viral loads,” she added.