Brazil virus variant found to evade natural immunity

The P. 1 Covid-19 variant that originated in Brazil and has spread to more than 25 countries is around twice as transmissible as some other strains and is more likely to evade the natural immunity people usually develop from prior infection, according to a new international study.

The research, conducted by a UK-Brazilian team of researchers from institutions including Oxford university, Imperial College London, São Paulo University, found that the P. 1 variant was between 1.4 and 2.2 times more transmissible than other variants circulating in Brazil. 

It was also “able to evade 25-61 per cent of protective immunity elicited by previous infection” with any earlier variant, the researchers found, in a sign that current vaccines could also be less effective against it.

International concern about the P. 1 variant has escalated recently, with more than 25 countries detecting the variant, including Belgium, Sweden and the UK, which has identified six cases.

The scientists are expected to release a paper describing the research on Tuesday. Dr Nuno Faria, the lead author, did not immediately respond to a request for comment. The study has not yet been peer reviewed.

The researchers have dated the emergence of the P. 1 variant to November 6, 2020, around one month before cases began to surge for a second time in the Brazilian city of Manaus. They found that the proportion of cases classified as P. 1 in Manaus increased from zero to 87 per cent in the space of 7 weeks. 

The paper concluded: “Our results further show that natural immunity waning alone is unlikely to explain the observed dynamics in Manaus, with support for P. 1 possessing altered epidemiological characteristics.”

“Studies to evaluate real-world vaccine efficacy in response to P. 1 are urgently needed,” it added.

The researchers also found that infections were 10 to 80 per cent more likely to result in death in Manaus after the emergence of P.1. However, the authors cautioned that it was not possible to determine whether this meant the variant was more lethal or whether it was a result of increased strain on the city’s healthcare system, or a combination of both. 

The P. 1 variant has over 17 mutations, which alter its genetic sequence from the virus originally identified in Wuhan, including 3 key changes to the spike protein that it uses to enter human cells.

Researchers in Brazil have been using genetic sequencing technology developed by Oxford Nanopore in the UK to identify and track the variant. The technology was first used in Brazil during the Zika outbreak in 2015.

Dr Leila Luheshi, director of applied and clinical markets at Oxford Nanopore, told the Financial Times that while the B.1.1.7 variant in the UK has similar properties of high transmissibility to P. 1 — it is thought to be around 1.5 times as transmissible as variants that preceded it — there was no evidence to date that it evaded past natural immunity in the same way. Studies so far have also shown that current vaccines retain their efficacy against B.1.1.7.

Luheshi said that the concern with P. 1 is that “because it has these mutations around the spike . . . the hypothesis is that the vaccine will be less effective.” But she added that there is not yet definitive evidence to support this theory.