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 <br /> <br />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.
