Third jabs ‘huge boost to immune system'

Covid booster shots can dramatically strengthen the body’s immune defences, according to a major study that raises hopes of preventing a winter wave of severe disease driven by the Omicron variant of the virus.

- Ian Sample

As the NHS continued to grapple with plans to offer booster vaccines to 25 million adults in the next two months, a further 10 Omicron cases were identified in England and Scotland yesterday, bringing the total to 42 and prompting public health officials to say community transmission was “almost certainly” occurring.

It is too early to say how effective current vaccines will be against Omicron, which is believed to be fuelling an exponential rise in Covid cases in South Africa but has been seen in relatively small numbers in Britain and Europe so far.

In a study published in the Lancet, researchers on the UK-based Cov-Boost study measured immune responses in nearly 3,000 people who received one of seven Covid boosters or a control jab two to three months after their second dose of either the AstraZeneca or Pfizer vaccine.

Those boosted with Pfizer after two doses of AstraZeneca had antibody levels a month later nearly 25 times higher than controls. When the Pfizer booster was given following two Pfizer shots, antibody levels rose more than eightfold.