Double Covid jab failing to create antibodies in some people with weak immune systems
Two in five people with weak immune systems have "low or undetectable" antibodies after two Covid vaccinations, research shows, prompting calls for the rollout of booster jabs.
Findings from the UK trial have been given to the Joint Committee on Vaccination and Immunisation (JCVI), which is preparing to issue recommendations on who should get a third jab.
In its interim advice, the committee suggested boosters might be offered to everyone over 50. But since then there have been suggestions that the next stage of the rollout may be far more restricted.
Last week, Prof Adam Finn, a member of the JCVI, said the committee was "trying to identify the people who are really at risk and really need that third dose".
More than one million people in the UK are immunosuppressed, while around four million are classed as clinically extremely vulnerable. Those with weak immune systems are now likely to be prioritised for jabs next month.
The group includes those undergoing treatment for cancer and stem cell treatment, as well as those with relatively common conditions such as inflammatory arthritis, and diseases of the kidney or liver.
Further studies on the wider population are expected to be handed to the JCVI over the next week before the committee takes a final decision on the next stage of the rollout.
In the new study, experts from the Universities of Glasgow and Birmingham examined the immune responses of 600 such patients after receiving two Covid jabs. Forty per cent were found to have a "low or undetectable" antibody response.
Scientists stressed that this did not mean they had no protection against infection, as it is not known what level is required. But they said it would be "very sensible" for such patients should be offered booster jabs while further research is carried out.
Earlier this month Sajid Javid, the Health Secretary, said: "We are going to have a booster scheme. It will start some time in September.
"I couldn't tell you exactly when because before we start it... we need to get the final advice from our independent scientific and medical advisers the JCVI, and so we're waiting for their final opinion."
In the US and Israel, some people are already being offered a third Covid jab.
In the latest study, researchers performed immune tests on blood samples and examined not only antibody levels in the blood but also the ability of a particular form of white blood cell, called a T-cell, to respond to the vaccine.
Around three in five people in the vulnerable groups were found to have an antibody response similar to those found in healthy adults. But 40 per cent generated a low antibody response compared to healthy people, according to the study, which has been published as a pre-print by The Lancet.
More than one in 10 failed to generate any anti-spike antibodies four weeks after being double jabbed.
The authors stressed that almost all the people who did not show any antibody response had vasculitis, a group of rare diseases which lead to inflammation of the blood vessels and can lead to damage of the tissues.
They said that, across almost all patient groups, the T-cell response was similar to healthy adults, indicating that some form of immunological response had been mounted even among those with undetectable antibody levels.
Researchers said the vaccine is "immunologically active" in all patients, but the data supported the need for an autumn booster campaign for those with a poor antibody response.
They stressed that the study was limited to measuring the immune response and did not examine the effectiveness of the jabs in protecting against infection, with work ongoing to measure this among the most vulnerable.
Prof Iain McInnes, the trial lead from the University of Glasgow, said: "Our data suggests that a booster for people who have mounted either an absent or lower level of antibody response would be a very reasonable next step."
