Officials in the US state of Oregon have identified a new mutant form of the highly transmissible coronavirus variant first found in the UK.
The new type has an important mutation in its spike protein that is thought to make the virus better able to evade the protection given by vaccines or previous infection.
Known as E484K, the mutation is also found in the previously identified South African and Brazilian coronavirus variants that some studies indicate are more difficult for vaccines to combat. It is also present in a New York variant.
US media are reporting that the new, mutated form of the UK variant was found among 13 samples collected from a Covid-19 outbreak in “a healthcare setting”.
Of the samples, 10 contained the UK variant – which has resulted in thousands of cases across the US – while one contained the new version.
Genetic analysis of the samples reportedly indicates that the new mutant was picked up from elsewhere in the community and did not evolve within the individual the sample was collected from.
"We didn't import this from elsewhere in the world – it occurred spontaneously," Dr Brian O'Roak, an associate professor at Oregon Health and Science University, told The New York Times.
Because the new mutant combines high transmissibility with increased ability to evade the immune system after vaccination, it could outcompete the original form of the UK variant, known to scientists as B1.1.7, which is thought to have emerged in south-east England in September.
In a briefing document on Sars-CoV-2 variants released last month, Public Health England wrote that E484K was “currently the mutation with most evidence of causing antigenic change”. Antigens are foreign substances recognised by the immune system.
“Several independent studies showing the impact of different antigenic variants have concluded E484K is among the single mutations with the greatest impact,” the document read.
It is “potentially more concerning”, the document stated, when found with N501Y, a mutation found in the UK, Brazilian and South African variants associated with increased transmissibility.
Public Health England estimates that the UK variant is 30 to 50 per cent more transmissible than original forms of the coronavirus, so the new mutant is likely to be similarly easy to pass on. It could become even more prevalent if vaccines are less effective at stopping it from being transmitted.
While new variants are concerning, Prof David Taylor, a professor emeritus of pharmaceutical and public health policy at University College London, said they were unlikely to be scupper efforts to control the pandemic.
“Will the vaccines be tweakable? Yes. It will cost money and you will have to have another vaccination round, but it will be doable,” he said.
“We should be celebrating the vaccines. [Researchers have] a technical base for improving them if and when necessary.”
Vaccine makers have already developed updated versions of their vaccines to cope with emerging variants, especially those first identified in Brazil and South Africa.
New versions of the Moderna, Oxford-AstraZeneca and Pfizer-BioNTech vaccines, among others, could be released later this year.
Updated vaccines are likely to go through streamlined testing procedures compared to those faced by the original vaccines, which were subject to extensive laboratory and clinical trials.
They could be given as booster shots to people already vaccinated, or combined with the existing vaccines as a bivalent vaccine, namely one that provides protection against two types of antigen.
While some shots have reduced efficacy against the new variants, developers of other vaccines, such as Russia’s Sputnik V, say tests indicate their products continue to perform well against them.
New variants arise because, when viruses replicate their genetic material as they reproduce, mistakes or mutations happen.
Mutations harmful to the virus are weeded out by natural selection, but those that make the pathogen better able to reproduce and spread tend to become more numerous within the virus population.
While numerous coronavirus variants have evolved, experts say the rate at which the pathogen mutates is actually quite low for viruses and slower than that of influenza, for example.
Just as amended vaccines are being formulated to cope with coronavirus variants, so new vaccines are typically introduced annually to cope with changes in influenza.