There are still concerns about how effective a single dose of vaccine will be against the South African strain. So far Pfizer and Moderna's studies have only looked at how people given two doses react to the SA variant.
Studies into how well Oxford University/AstraZeneca's jab will work against the South African strain are still ongoing. Johnson & Johnson actually trialled its jab in South Africa while the variant was circulating and confirmed that it blocked 57 per cent of coronavirus infections in South Africa, which meets the WHO’s 50 per cent efficacy threshold.
IIRC, both the Pfizer and Moderna vaccines were said by the companies to be no more than 50% effective in single jab mode. Pfizer has developed a booster shot to counteract the SA strain and Moderna announced that one is under development.
Furthermore there is a growing body of research indicating that antibodies in those previously seriously infected with Covid-19 are, in many cases, proving ineffective in protecting against the SA virus. Today, SKY News broadcast that testing at Cambridge University shows the Pfizer vaccine is proving ineffective in combatting the SA virus in the over 80's - so another note of caution here. (*)
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My personal POV, is that "vaccine nationalism" be damned. The supplies should be adequate to cope with high vaccination rates throughout the European continent within the next 8-10 weeks. In the British case, vaccines are something of a 'Hail Mary' given the tragically high death toll. So far it's going well - long may it continue.
(*) In the chart, Sanofi-GSK are manufacturing the Pfizer/BioNTech vaccine under licence.
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https://www.cam.ac.uk/research/news/pfizer-biontech-vaccine-likely-to-be-effective-against-b117-strain-of-sars-cov-2The preliminary data, which have yet to be to peer-reviewed and relate to only a small number of patients, also suggest that
a significant proportion of over-eighty olds may not be sufficiently protected against infection until they have received their second dose of the vaccine.