Israeli research shows 50-fold increase in antibodies after third stroke
The report, published Wednesday in Lancet Microbe by Esther Saiag, deputy director of information operations at Tel Aviv Sourasky Medical Center, and her colleague Dr David Bomve, examined the effect of the third dose on 346 healthy hospital workers. .
She said these workers tend to be healthier and more active than average citizens, and because of the role they played in the pandemic, they were among the first to get vaccinated.
Most of these workers received their second injection eight months before their third injection. Israel began its vaccination campaign on December 20, and medical staff were among the first group to be vaccinated.
When the country opened third doses to healthcare workers in August, Saiag asked if any of the older staff would be screened to check their antibody level before getting vaccinated. Some 346 people aged 64 to 73 (215 women) have complied.
The test found that in August the median baseline level of antibodies was very low – only 3.67.
While antibodies don’t tell the whole story of immunity, as cellular memory is also important, Saiag said that number is very low.
Those who were screened before the stroke returned 10 days later to be tested again. The majority (95.7%) had an increase in antibodies up to 150.
The anti-spike protein concentrations were established with the ADVIA Centaur SARS-CoV-2 IgG test, which provides an index value of up to 150, the Lancet article explained. An index equal to or greater than one is considered reactive.
“We saw this very soon after enough of the population received the third reminder that the fourth wave had subsided,” Saiag said. “Now we see what was going on behind the scenes. We have this increase in antibodies. Maybe we all expected to find this, but now we have the data to prove it. “
Only two subjects did not respond at all and the antibody level in their blood remained negative. A small number of additional subjects responded with only a moderate increase in antibody level, despite the booster dose.
A follow-up study is now planned to investigate the possible causes of the lack of response or the non-maximal response in these subjects.
This is the largest study of its kind to examine the effect of the booster dose in healthy hospital staff.
Saiag said the plans are to continue following this group and review them at six, eight and 10 months to see what is happening with their antibody levels. They will also check with staff whether any of them contract COVID and, if so, whether they have any symptomatic or asymptomatic cases.
The results could help governments, including the Israeli government, decide whether or not a fourth dose is needed, Saiag said.