Viruses are constantly mutating, including the new coronavirus that caused the global pandemic. But a variant that surfaced in South East England in September is of particular concern and leads to an emergency lockdown in London over Christmas and causing countries including Canada, France and Germany to stop flights and suspend rail connections.
1. Why is this mutation alarming?
Dubbed the “B.1.1.7 lineage,” the species has undergone nearly a dozen genetic changes from the virus that emerged from Wuhan, China in late 2019 – far more than is normally seen. That includes changes in key areas of the virus involved in its ability to infect humans. Preliminary analysis in the UK suggests it could be as much as 70% more transmissible than other circulating SARS-CoV-2 strains and may contribute to spike in country cases. Maria van Kerkhove, the World Health Organization’s technical leader at Covid-19, told the BBC on Dec. 20 that WHO is working to understand the extent to which the virus can more easily spread, along with other human behavioral factors that may be causing its transmission. It is also investigated whether the mutation causes more serious disease and can evade the antibodies generated by vaccination.
2. What is known about when it came up?
The two earliest known specimens were collected in in late September in London and the nearby Kent area, and cases continued to be found until early December. One reason why the new variety spread was that its emergence coincided with the holidays traditionally associated with greater family and social mixing. Scientists have hypothesized that the strain may be due to the transmission of the virus from a chronically infected patient.
3. How quickly did it spread?
On December 15, 1,623 virus samples were identified as belonging to the B.1.1.7 lineage. Of these, 519 were collected from patients in Greater London, 555 in Kent and 545 in other regions of the UK, including both Scotland and Wales. Cases have also been identified in Denmark, the The Netherlands, Belgium and Australia. Only since about 10% of SARS-CoV-2 samples from UK patients undergo genetic sequencing, the number of known cases is an underestimation of the true number of infections. Infection rates in areas where the strain is circulating rose faster than expected, Public Health England said on Dec. 20, adding that additional analysis showed it has a higher transmission speed than other variants in circulation. Paul Hunter, a professor of medicine at the University of East Anglia’s Norwich School of Medicine, told the Science Media Center that the new variant was responsible for 62% of SARS-CoV-2 infections in London in the week ending December 9, against 28% of infections there in early November.
4. How many other mutations are there?
Viruses are constantly changing due to mutations that arise naturally as they multiply and circulate in their hosts. As a result of this ongoing process, many thousands of mutations and several lines have already emerged in the SARS-CoV-2 genome since the virus emerged in late 2019. As mutations continue to emerge, more and more new variants are being found, with the vast majority of mutations having no apparent effect on the virus. However, scientists are paying most attention to mutations such as those that have occurred in the new British strain involving the gene encoding the SARS-CoV-2 spike protein, which is associated with viral access to cells and immunity and efficacy of the vaccine.
5. Will vaccines still be effective?
The extent to which SARS-CoV-2 can evolve to escape immunity caused by infection or vaccination is currently unknown. Studies are underway to better understand that. The WHO’s of Kerkhove told the BBC that current information suggests the new variant will not have any impact on the vaccines being rolled out. Over time, as more mutations occur, vaccines may need to be changed. This happens with the seasonal flu, which mutates every year, and the vaccine is adjusted accordingly. Unlike flu, coronaviruses have a proofreading mechanism, which means they don’t mutate as quickly as the flu virus. Covid-19 vaccines that have proven effective in trials so far may be easily adjusted as needed, BMJ medical journal reported Dec. 16.