Two COVID jabs should still slash the risk of dying from Omicron by up to 84 per cent but a booster is twice as good at preventing someone from falling ill, according to official estimates.
SAGE modelling published over the weekend worked off the assumption that two Pfizer doses give 83.7 per cent protection against hospitalisation and death from the highly-evolved strain.
A two-dose course of AstraZeneca’s vaccine was estimated to reduce the risk of severe disease from Omicron by 77.1 per cent. However, both vaccine brands were assumed to wane within three to six months.
At that point, Government’s scientific advisers believe protection from two AstraZeneca jabs could be as low as 61.3 per cent and 67.6 per cent for Pfizer.
A booster dose of Pfizer’s vaccine was estimated to top-up immunity to over 93 per cent, regardless of which jab someone was originally given — providing a similar level of protection as two doses did against Delta.
The estimates were presented in modelling by the London School of Hygiene and Tropical Medicine (LSHTM) on Saturday and are based on lab studies looking at antibodies.
The model warned that the vaccine-resistant Omicron variant may lead to more hospitalisations than England’s second wave last January when up to 4,000 infected patients were being admitted to NHS facilities every day.
Scientists have been racing to work out how effective existing vaccines will perform on the Omicron strain since it was first discovered on November 24. There was huge concern that it would be unrecognisable to jabs because of the 30-plus mutations on its spike protein.
Current jabs were designed to target the original virus that emerged in Wuhan. But because the variant is so new, experts are still relying on lab experiments that may not reflect how the variant will behave in the real world.
Professor Paul Hunter, an expert in infectious diseases at the University of East Anglia, told MailOnline he expects two jabs to protect against severe illness even better.
He said hospital data in South Africa’s Omicron ground zero suggested T cells, which are more difficult to measure, were playing a crucial role in immunity.
However, Dr Simon Clarke, a microbiologist at Reading University, argued the drop in efficacy of two jabs was still ‘concerning’.
He told MailOnline: “Nobody ever expected Omicron to wipe out vaccine efficacy, it was just a drop that was expected — and that in itself can do enough damage.’”
Even at 84 per cent protection from severe illness, that leaves 16 per cent vulnerable to being hospitalised or killed by Omicron. That’s up to three times as many as with Delta.
Professor Hunter told MailOnline that there were ‘grounds for optimism’ based on the paper’s estimates.
– MailOnline
