Double Pfizer recipients' blood neutralises Omicron a little, but double AstraZeneca blood doesn't

Embargoed until: Publicly released: 2022-01-13 09:00

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A small Austrian study tested the ability of serum (blood) samples from people who had a previous COVID-19 infection and people who had received various COVID-19 vaccines to see if they acted against Omicron in a dish. The scientists say samples from vaccinated participants neutralised the Omicron variant to a much lesser extent than any other variant analysed (Alpha, Beta, or Delta). Serum from people who had received two Pfizer jabs neutralised Omicron to some degree, they say, as did blood from people who had received one Pfizer and one AstraZeneca jab. But serum from people who had only received the AstraZeneca vaccine was ineffective in neutralising Omicron. The scientists have yet to analyse blood from people after three vaccine doses.