Last week we heard a lot in the media about a new genetic variant of the SARS CoV2 virus in southern England. Several countries have imposed travel limitations in response to the reports. Here’s some background about what’s going on.
Public Health England wrote last week about a cluster of genetically similar cases in mid-November. They found that the cluster is genetically distinct from the rest of cases in the UK.
An investigation of the cluster found that the virus causing the cluster appears to be transmitted more easily than other variants (the reproduction rate is higher). The virus doesn’t appear to be more lethal.
The variant has mutations in the genetic code that effect the receptor binding site on the viral coat. The authors hypothesize that the changes in the receptor binding affinity of the spike protein enhances the transmissibility of the virus. They think it’s possible that the changes in this strain make antibodies less effective at neutralizing the virus.
So far, there’s no evidence that this particular variant (and there are thousands of variants) poses a risk to vaccine effectiveness. Vaccines are made such that they can accommodate genetic changes. The influenza virus is completely different in that it’s prone to major antigenic shifts- which is a big reason why we have new influenza vaccines each year.
Also, this virus was identified in mid-November, more than a month ago. That means it has been circulating far more widely in Europe than is currently known and possibly in the US as well. Implementing travel restrictions as is happening in Europe is unlikely to make a meaningful difference and diverts attention from the core public health measures that we do know slow the spread of the virus. Here’s CDC’s brief and factsheet about the emerging variant.
