For a few weeks, there has been a rapid increase in COVID-19 cases in the southeast of England, which has led the British authorities to tighten restrictive measures in the face of the Christmas holidays. Analysis of the viral genome sequence data has identified a large proportion of cases belonging to a new variant of SARS-CoV-2. The new strain has several mutations in the spike, which is the protein that the virus uses to enter human cells and, according to the European Center for Disease Prevention and Control (ECDC), could have a transmission capacity of up to 70 times higher. Although at the moment it does not seem that this new variant, provisionally called VUI-202012/01, is more lethal or produces more serious infections, it is still too early to know the details.
In any case, viruses mutate very frequently and this is not the first variant found that worries health authorities, for example, last summer in Denmark, millions of minks infected with another variant of SARS-CoV-2 had to be slaughtered. posing a significant risk to humans. The inevitable question we all ask ourselves is: will vaccines also be effective for these new variants of the virus that appear?
“We are not seeing any increase in virulence (clinical severity) or major changes in S (spike protein) that reduce the effectiveness of the vaccine, so far,” explained Julian Tang, honorary professor of clinical virology at the University of Leicester speaking to Science Media Center (SMC). “ Over time, new viruses adapt to their hosts, with decreasing mortality and possibly increasing transmissibility . It does not make sense for the virus to kill its host: it is better that it replicates at high levels but causes few symptoms. ” In short: asymptomatic patients are very good for the virus, as they continue to move and lead a normal life, allowing the virus to continue spreading and replicating its genetic material in more people. “It is likely that we are now seeing part of this new host adaptation process in SARS-COV-2, but it remains to be seen if mortality will be different with this variant than with the previous one,” says the expert.
Is PCR capable of detecting the new variant?
Another question that arises is whether the tests that are routinely used are capable of detecting the new strains. The director of the SARS-CoV-2 Genomics Initiative at the Wellcome Sanger Institute explains to SMC: “One of the VUI-202012/01 mutations removes six nitrogenous bases that code for amino acids 69 and 70 of protein S. This region is just one of the three genomic targets used by some PCR tests , so in these tests a false negative could be obtained in that channel. However, the other two targets are not affected by mutations in the new variant, so that the test, which combines the three channels, is still capable of detecting the virus ”, explains the expert. ” I am not aware of any commercial tests that use a single target on this part of the viral genome , but if there are, they should be carefully investigated to avoid false negatives.”
ECDC also recommends reviewing the performance of PCR tests and tracking suspected COVID-19 reinfection cases by sequencing viruses isolated from these cases to identify new variants. “ With the implementation of vaccination, close monitoring of people vaccinated with COVID-19 must be guaranteed to identify possible vaccination failures and breakthrough infections. The viruses isolated in these cases must be sequenced and characterized genetically and antigenically ”, indicates the agency in its report on the new variant of SARS-CoV-2.
