Ireland has almost as many cases of P1, one of the most worrying Covid-19 variants of concern, as the UK, despite a much smaller population.
Nine cases of P1, which is more transmissible and could evade the immune response provoked by vaccines, have been identified in the Republic, according to the National Public Health Emergency Team.
The UK had recorded 10 confirmed cases of the variant up to Monday.
The number of cases of the variant has crept up since a first Irish case was identified in mid-February, despite mounting restrictions on international travel and focused tracing of contacts of cases.
P1, which was first identified in Brazil, has been blamed for a big resurgence of Covid-19 in the northern city of Manaus in December and January. There was also some evidence that people who were previously infected were reinfected with the new variant.
The first three Irish cases were part of a travel-related cluster among people who had travelled from Brazil.
Like the South African variant, P1 includes a key mutation, called E484K, which may help the virus evade antibodies, part of the immune system.
Ireland has a further 13 cases of P2, another potentially problematic Brazilian variant which is under investigation.
Dr Cillian de Gascun, director of the National Virus Reference Laboratory, says the reasons for the increase in P1 cases aren’t clear.
Increased testing capability may be contributing to more cases being identified. “We have significant pockets of population from Brazil and who may have travelled over the Christmas period,” Dr de Gascun adds.
P2 doesn’t appear to be as transmissible as P1, he says.
Despite initial fears that P1 could reduce the effectiveness of vaccines, a recent study by scientists at the University of Oxford suggests natural – and vaccine-induced – antibodies can still neutralise this and other problematic variants, but at lower levels.
The P1 strain may be less resistant to these antibodies than first feared, it found.
Manaus has attracted scientific scrutiny because it was badly hit in the first Covid-19 surge last year. This led some scientists to claim herd immunity had been reached and the virus would no longer spread. However, resurgence of the disease in the city has been blamed on P1’s resistance to previously generated immunity.
The good news for Ireland is that the currently dominant B117 variation, which rapidly became dominant from December and now accounts for over 90 per cent of cases, is impeding the spread of other possibly more worrisome variants.
“I think it will be difficult for other variants of concerns to gain a foothold here, though I don’t think we should be complacent. B117 certainly appears to have a fitness advantage over most of the variants at this point in time,” says Dr de Gascun.