The Manaus variant of coronavirus, detected in Ireland last month, could cause reinfection for between 25% and 61% of people who have previously had Covid, a new study suggests.
Research on the P1 variant among people living in the Brazilian city of Manaus found potentially high levels of reinfection, and that the variant was more transmissible than the original pandemic strain.
According to the latest study, from organisations including Imperial College London, Oxford University and the University of Sao Paulo, blood studies suggest more than 67% of people in Manaus may have had Covid by October 2020.
There was surprise, then, when the city suffered another huge wave of Covid-19 at the start of this year, so experts sought to find out why.
They found the proportion of Covid cases that were the P1 variant grew from zero to 87% in about eight weeks.
P1 was found to be 1.4 to 2.2 times more transmissible than other variants in Manaus, and was found to evade 25% to 61% of protective immunity from previous infection.
Dr Nuno Faria, reader in viral evolution at Imperial, told a briefing:
He said more work was needed on patterns that might occur in other countries, adding: "We know that vaccines are effective and they can protect us from infection and from disease and death.
"This is a period to be optimistic about the future. The more we know about the virus, the better we're able to protect against it and I think there's no concluding evidence to suggest at this point that the current vaccines won't work against P1."