In the last week, we have seen a number of reports on the emergence of a new SARS-CoV-2 'mutant' or variant in the United Kingdom.
RNA viruses such as SARS-CoV-2 mutate continuously. This is perfectly normal and a large number of variants have already been documented since the first emergence of the virus in 2019. The majority of these mutations are 'neutral' i.e. they don't make any significant difference to the transmissibility, infectiousness, and severity of COVID-19. However, once in a while, mutants emerge that really make a difference. A good example is the infamous D614G SARS-CoV-2 variant, which is more transmissible (Hou YJ et al, Science, 2020) and rapidly became the main circulating variant worldwide.
What is VUI 202012/01?
The UK has seen a rapid rise in COVID-19 activity over the last month or so, particularly in South East England. Genetic analysis showed that a new SARS-CoV-2 variant (called VUI 202012/01) emerged around the same time and rapidly took up a large share of circulating variants in the UK. This indicates a possible association between this new variant and increased COVID-19 spread, which is supported by infectious disease modelling analysis. Luckily, there is no evidence so far that VUI 202012/01 causes more severe disease or increased hospitalization. The variant has probably spread widely within the UK and has also been found in Denmark, Netherlands and Australia indicating spread by international travel.
Why are we so worried about VUI 202012/01?
Apart from the tentative association with increased COVID-19 transmission, the variant appears to have mutated more than expected for usually circulating strains. What is particularly worrying is that VUI 202012/01 has accumulated a lot of mutations in its 'spike' protein. The spike protein is the part of the virus that is recognised by our immune systems and forms the main target of nearly all approved vaccines to date. The impact of these mutations on the effectiveness of prior immunity or vaccines needs to be rapidly elucidated. Luckily, this is quite easy to do and we should know about the effect of these mutations by the end of January. Until that time, it is crucial to contain VUI 202012/01 and prevent it from gaining a foothold in other countries.
Where does VUI 202012/01 come from?
We don't know, but given that the number of mutations is more than expected from a normally circulating variant, there are two main possibilities raised by the Europe CDC. The first possibility is prolonged SARS-CoV-2 infection in an immunocompromised person (person with weakened immunity) who then sparked a major outbreak. Such patients have been reported previously and viruses can mutate rapidly in such immunocompromised persons (Choi BJ et al, NEJM, 2020). The second possibility is spread from another animal capable of harboring the virus (such as cats or mink). Investigations into this are ongoing. A third possibility that VUI 202012/01 is circulating in humans elsewhere and was imported into the UK is unlikely given the difference between VUI 202012/01 and the thousands of other SARS-CoV-2 sequences in genome databases.
What should we do about VUI 202012/01?
1.HK should act decisively and rapidly to STOP arrivals from the UK until the situation becomes clear. I understand that this is the holiday season and thousands of arrivals are anticipated. However, HK is in a highly precarious situation already with ongoing community transmission and stretched quarantine facilities. We all know that the border control net can never be 100% leak-proof. The introduction of a variant with essentially unknown effects on COVID-19 vaccine efficacy into the city at this juncture would be disastrous. It is a hard decision, but one that must be taken quickly.
2.If arrivals from the UK are not stopped, they must be under strict supervised quarantine for 21 days in government facilities (NOT hotels). Mandatory testing must be done at arrival and at regular intervals during the quarantine.
We don't know if VUI 202012/01 is a time bomb. But we must definitely treat it as one.
First published on the author's facebook