Parts of England have been plunged into 'tier 4' restrictions this evening, including the part in which I live. Previously, the highest tier of restrictions was 'level 3'.
The reason is the new strain mentioned by August here which has arisen in the south of England, which is causing concern:
Deadly Wuhan Coronavirus
The government is saying that the new strain is up to 70% more transmissible than other dominant strains in the country. Apparently it contains the H69/V70 deletion that made the Danish mink strain, but which had evolved independently in a few other locations, like the Netherlands, over the summer. It also contains another mutation, called N501, to the spike protein, in an are called the receptor binding domain, which is the part of the virus which binds to human ACE2, leading to infection.
There were reports of
in vitro testing back in early November indicating that the virus with the H69/V70 deletion is less susceptible to human SARS-CoV-2-specific antibodies. The government has not said exactly why they believe that the strain transmits 70% more easily. The Prime Minister, Boris Johnson, said in an address to the nation this evening that it increases the R rate of the virus by about 0.4. The median R-nought number was previously 5.7, so that would make it 6.1 for the new strain.
According to this tweet by a researcher, the strain has also been detected in Denmark, and as of the 14th of December, England and Denmark were the only two countries to have identified this strain.
Somewhat ironic given that Britain was the only country, that I know of, which imposed restrictions on people entering the country from Denmark after the announcement of the new mink strain there at the beginning of last month. England was also in a national lockdown for a month, until the 2nd of December, where outward travel was not generally not allowed, unless for special reasons.
Authorities are saying that there is no evidence that it affects vaccine effectiveness. However, that may be taken to mean that there is also no evidence that it does not affect vaccine effectiveness. Some experts have said that it is unlikely, because you would need multiple different mutations to the spike protein to alter vaccine effectiveness. However, the proof will be in what happens. There were experts who assured us that it was unlikely that Covid-19 would lead to a global pandemic.
It would probably be a good idea for other countries to bar entry to travellers from England for the time being.