Covid booster shots may only be needed for about 40% of immunosuppressed people, preliminary UK data suggests.
Researchers looked at immune responses after two shots of either the Oxford/AstraZeneca or Pfizer/BioNTech vaccines in people with compromised immune systems, due to underlying disease or the medicines they are taking for their underlying disease.
Participants in the “Octave” study – led by the University of Glasgow – included those with cancer, end-stage kidney disease, and chronic conditions such as rheumatoid arthritis and inflammatory bowel disease.
The findings – which come from the first 600 immunocompromised participants recruited in the study – showed that about 60% of the participants mounted an antibody response similar to healthy people about four weeks after their second dose.
About 11% had no antibody response (a majority of these were people suffering from vasculitis), while the rest showed a sub-par response, the researchers said in their still to be peer-reviewed report.
“We don’t know what this antibody response means yet. We know that it’s less than the healthy control, but we don’t know whether that means these patients are more vulnerable to Covid-19,” said Prof Pam Kearns, deputy chief investigator of the trial and director of the University of Birmingham’s Institute of Cancer and Genomic Sciences and the Cancer Research UK Clinical Trials Unit.
“We can speculate that may be the case, but we don’t know that for certain. But certainly, a booster vaccine … gives these patients an opportunity to have a better response.”
A follow-up trial to the ongoing Octave study is expected to answer questions about whether a third booster vaccine will help the fraction of those with no or low antibody responses mount a response in line with healthy people, the researchers said.
Prof Iain McInnes, Octave’s chief investigator and vice-principal at the University of Glasgow, said that for now, “our data suggests that a booster for people who have either an absent or lower level of antibody response would be very reasonable”.
Researchers still do not understand the level of antibodies or other immune system soldiers, such as T-cells and B-cells, required to protect from Covid-19 – particularly from serious illness and death.
In the Octave study, the T-cell responses in almost all participants were comparable with those of healthy people, the researchers found.
“So, there is a robust T-cell response being generated,” said Prof Carl Goodyear, Octave co-investigator and professor of translational immunology at the University of Glasgow.
“I think the important point to stress is the vaccine is actually immunologically active in all patients … it’s the type of response and the quality of the response we’re really trying to understand here.”
Overall, it is reassuring that even those who did not make antibodies, did mount a T-cell response, added McInnes.
“We’re quite reassured that even patients on quite significant immune-suppressive [drug] regimes are mounting … this T-cell response, and that gives us optimism that there is indeed a degree of virus protection, even for those whose antibody levels may be negative.”
