The coronavirus variant first detected in Brazil, known as P1, is estimated to be roughly twice as infectious as other mutated forms of the virus and can partially evade immunity elicited by previous infection, early research suggests.
A study into people infected with P1 in the Amazonas city of Manaus has shown the variant carries a “unique constellation of mutations” which makes it between 1.4 and 2.2 times more transmissible.
And in a sign that P1 may diminish the effectiveness of the Covid-19 vaccines, it is also “able to evade 25-61 per cent of protective immunity” caused by previous infection with other variants, the scientists said, adding that their data was preliminary.
Experts cautioned that the research cannot be used to predict what may happen in the UK, and say it does not suggest that vaccines will not work against the variant.
P1 has been associated with a large second wave of infections that ripped through Manaus in late 2020 and early January. This is despite previously high levels of immunity in the local population, with 67 per cent of people estimated to have been exposed to coronavirus by October last year.
The scientists found that the proportion of infections in the city caused by P1 variant grew from zero to 87 per cent in about eight weeks.
Dr Nuno Faria, reader in viral evolution at Imperial College London and lead author of the study, told a briefing on Tuesday: “If 100 people were infected in Manaus last year, somewhere between 25 and 61 of them are susceptible to reinfection with P1.”
The paper, which has not yet been peer reviewed, is limited exclusively to the Manaus outbreak; because of this, the scientists warned against drawing wider conclusions from their findings.
“We caution that our results for Manaus should not be generalised to other epidemiological contexts and, or other variants of concern,” Dr Faria said.
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.”
Professor Sharon Peacock, head of the UK’s genetic surveillance programme, similarly said that it was too early to jump to conclusions.
“You can’t take the results of a study such as this and speculate on vaccine efficacy,” she told the briefing. “I think you’d need to see that in clinical studies. We don’t have enough information.
“This information we’ve seen today is very important but we mustn’t over interpret the data that has been presented.
“We’ve already said that vaccines are going to be highly effective in the UK and that’s about as far as we can go.”
To date, P1 has been reported in 25 countries across the world, including the UK, where a total of six infections have been detected so far by the Covid-19 Genomics UK consortium (Cog-UK).
However, officials are racing to hunt down one person whose identity and whereabouts is unknown. Public Health England believes the individual, who tested positive for P1, used a home kit on 12 or 13 February, but did not complete their registration form properly.
The latest study said that P1 carries a total of 17 mutations, including a trio of genetic changes in the virus’ spike protein – the part responsible for binding with human cells – that have been spotted in other variants.
The Brazilian variant features the E484K mutation, which is thought to help the virus partially evade neutralising antibodies produced by the body following natural infection or vaccination.
It also carries the N501Y mutation, which is associated with higher levels of transmissibility but does not appear to impact vaccine efficacy.
The researchers said it was unclear if infection from the variant is more likely to result in death.
“The recent epidemic in Manaus has strained the city’s healthcare system leading to inadequate access to medical care,” they write. “We therefore cannot determine whether the estimated increase in relative mortality risk is due to P1 infection, stresses on the Manaus healthcare system, or both.”
The scientists call for detailed clinical investigations of those infected with P1, along with studies on real-world vaccine efficacy and enhanced global genomic surveillance of coronavirus variants.
Although both the Brazilian and South African variants share a number of characteristics and have driven a large spike of cases in their respective countries, scientists do not believe they have the means to outcompete the Kent variant which has become widely seeded in the UK.