New Coronavirus Mutation Enhances Spread
The Wall Street Journal reports that countries across Europe and beyond are banning travel from the UK in order to stem a more-infectious strain of Covid-19 that has been found in the London area. The new strain was first reported last Monday, and on Saturday, England announced that it is imposing fresh lockdowns in London and surrounding areas, which also include a ban on households mixing at Christmas. Similar restrictions have been taken across Europe with Italy announcing a complete lock down across the country. Germany and the Netherlands imposed lockdowns through Christmas, and Austria said Friday that nonessential businesses will be closed starting Dec. 26. However, it also appears that the new strain has popped up in Denmark and South Africa. Holland reported one case with the new virus variant.
Scientists believe the new strain of the coronavirus could be as much as 70% more transmissible than previous strains, but there is no evidence at this time that it is any more deadly or more resistant to the vaccines.
It seems that the virus mutated to change the spike protein on the surface of the virus, increasing the protein’s ability to cling to and chauffeur the virus into human cells. These changes allow the mutation, known as N501Y, to spread faster than other versions of the virus. Early analysis suggests the variant first occurred in September either in London—where it was identified on Sept. 21—or in the nearby county of Kent, where it was found on Sept. 20. That might explain why quarantine restrictions that have been effective elsewhere in England have not been effective in Kent. By mid-November, 28% of cases in London were attributable to the new variant. In the week starting Dec. 9, it was responsible for 62% of cases in the capital. In other words, this variant is winning the infection race against all other CoV-2 strains out there. As of December 19, there has been no evidence of the new strain in the US.
Viruses mutate all the time, but coronaviruses do so less than, say, the flu virus. Mutations happen when rare, random errors are made while cells copy millions of viral genomes. Most mutations are innocuous, but sometimes these accidental changes alter the behavior of the virus. Scientists have identified 23 genetic changes in the genome of the new variant, an unusually large number, some of which are associated with small changes in the proteins the virus makes, which, therefore, can change viral behavior. Those include changes in areas known to be associated with how the virus binds and enters cells, which probably explains why it spreads more quickly. While efforts, including quarantine measures and the new vaccines, are designed to drop the infection rate of the virus, or the R0 number, these mutations threaten to work against those efforts and increase the virus R0 value.
Two main questions are now being investigated: Is the new variant more likely to cause increased morbidity and/or mortality, and is it more likely to avoid the body’s immune responses, including those encouraged by vaccines? The provisional answers to those questions are no and no, but the research continues, so these conclusions are preliminary. We will see.
The new variant isn’t the first time a more-transmissible CoV-2 strain has emerged. As reported in these pages last summer, scientists in July described a viral variant that displaced an older strain of coronavirus to become the dominant strain in the global pandemic. Experiments showed that the variant replicated more quickly in tissue culture, but appeared to be just as susceptible to antibodies that targeted the earlier strain, and was not associated with more severe illness.
The bottom line is that as viruses replicate in cells, spread, and replicate some more, they acquire small mutations in their genome. It is like playing the lottery, an occasional mutation will be the “winner” and the ability to spread and even cause new diseases can arise. Like the lottery, the more you play the greater the chance of a winner. This is why calls for “natural herd immunity” by letting people get infected are really bad ideas--they are gambling that while spreading through a population, the virus does not become even more virulent. This also is why health professionals recommend quarantine measures to limit the reproduction-spread-more reproduction of the virus until we have vaccines that effectively block the reproduction and spread and mutation of the virus.
Otherwise, we are just playing the virus lottery.
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