More than six million people’s booster immunity may have already waned by the new year, data show, raising the prospect of fourth jabs.
Government data show that protection against getting sick with omicron is as low as 35 per cent 10 weeks after a booster.
On Oct 23, 10 weeks before Jan 1, one in 10 people in the UK had already had a booster jab, with 6,026,503 third doses administered. Now half the population has had a booster, with 32.3 million jabs given by Dec 23.
Israel announced earlier this week it was preparing to give fourth doses to over-60s, and a senior government source said that it was “definitely a possibility” in the UK but stressed no decisions were imminent.
“It is not the focus of things this minute but I wouldn’t rule it out happening in the future,” the source told The Telegraph.
Any decision would be taken by the Joint Committee on Vaccination and Immunisation. Earlier this month Prof Chris Whitty, the Chief Medical Officer for England, said it was too early to decide whether a fourth jab for millions of people would be needed soon.
There is, however, a wide expectation among government figures that an annual autumn Covid vaccination campaign will be needed to protect against new variants.
Preliminary analysis from the UK Health Security Agency, published on Thursday, revealed that people who initially received two doses of AstraZeneca and then a booster have 35 per cent protection against getting sick with omicron 10 weeks after their booster.
For people who got two Pfizer jabs, followed by a Pfizer booster, the protection dropped from 70 per cent to just 45 per cent after 10 weeks.
‘I think we’re getting a little bit ahead of ourselves by just measuring antibodies’
The protection from boosters appears to decline quicker than it did after a second dose, but a person still has much better protection than if they do not get their booster jab.
Protection against severe disease, hospitalisation and death is also likely to be much higher for longer, experts believe.
This rapid drop-off in protection was called “surprising” by Dr Clive Dix, the former chairman of the UK Vaccine Taskforce. But he added this does not necessarily mean fourth doses and yet more boosters should be rushed out.
“I think they’re rushing and at this point shouldn’t be making the decision to [give a fourth dose],” he told The Telegraph.
“I think we’re getting a little bit ahead of ourselves by just measuring antibodies and neutralising antibody responses in the lab.
“We’ve known right from the start, even with the very first variants, that most of the vaccines didn’t perform very well in neutralising assays against the variants. But that doesn’t follow through in terms of serious illness and death.”
Dr Dix believed it is likely to do with another aspect of our immune response: cellular immunity.
T cells are specialised white blood cells that destroy any cells that have been infiltrated by the virus, and although they do not stop infection from occurring, they stop it from causing illness and death.
“If you look at all the data, there isn’t a great correlation between neutralising antibodies and protection from severe illness and death, they don’t seem to correlate,” he said.
“And that’s almost certainly because the cellular immune response is the important thing to stop serious illness and death.”
Dr Dix believed that instead of giving boosters after only a handful of months, it may be time to change tack and focus less on antibody levels and more on eliciting the strongest possible T cell response which can provide long-term protection that lasts for several years.
Pfizer’s and Moderna’s mRNA vaccines are the only ones used in the booster campaign and give a rapid surge in antibody levels. However, vaccines of a different design, such as the Novavax, AstraZeneca or Valneva jab, may provide a more robust T cell response, he said.
Clare Bryant, professor of immunology at the University of Cambridge, told BBC Radio 4’s Today programme that she believed fourth doses in the near future are likely, but the T cells will protect most people who develop symptoms from getting seriously ill.
“We are looking at fourth shots, I suspect. But don’t forget you’re still very well protected against severe disease and that’s absolutely critical,” she said.
“And that’s because there are two components of the vaccine that are important for protection. One is the antibodies but the other is the killer T cells, which take out infected cells; cells that are infected with the virus.
“And so at the moment, we think that those will still be working very efficiently in response to omicron or any other virus and they’re the ones that are super important for protecting against severe disease.”