Booster dose of Covishield vaccine effective against Omicron, UK study finds

A third booster dose of COVID-19 vaccine provides 70-75 per cent protection against symptomatic infection from the Omicron variant, the UK Health Security Agency (UKHSA) said on Friday.

In its latest technical briefing, the agency said that two doses of both the Oxford/AstraZeneca - administered in India as Covishield - and Pfizer/BioNtech vaccines provide "much lower levels" of protection against symptomatic infection compared to the currently dominant Delta variant of COVID-19.

However, a third top-up dose does seem to boost immunity against the new variant, based on an analysis of data from 581 Omicron cases.

"It is projected that if current trends continue unchanged, the UK will exceed one million infections by the end of this month," the UKHSA said.

"The preliminary data showed effectiveness against the new variant appears to increase considerably in the early period after a booster dose, providing around 70-75 per cent protection against symptomatic infection. Due to the early nature of the findings, all estimates are subject to significant uncertainty and are subject to change," it said.

The health experts reiterated that vaccines were still likely to offer good protection against severe COVID, which required hospital treatment.

Dr Mary Ramsay, Head of Immunisation at the UKHSA, said: "These early estimates should be treated with caution but they indicate that a few months after the second jab, there is a greater risk of catching the Omicron variant compared to Delta strain.

"We expect the vaccines to show higher protection against the serious complications of COVID-19, so if you haven't yet had your first two doses please book an appointment straight away."

She highlighted the current guidance of working from home where possible, consistently wearing masks in crowded or enclosed spaces, washing your hands regularly and isolating and getting tested if you feel unwell as vitally important in reducing the impact of COVID-19.

The scientific analysis is released as the UK recorded another day of high daily infections at 58,194 on Friday.