In recent weeks, a handful of new coronavirus variants have emerged, sparking fears they may be more transmissible, lethal, or evade immunity acquired by prior infection or vaccines.
On Friday, Prime Minister Boris Johnson suggested there was early evidence suggesting that the UK, or Kent, variant may be more deadly, although government scientists stressed that the data so far is uncertain. Here’s what we know so far.
How many new variants of SARs-Cov-2 are there?
There are many but three major “variants of concern” are currently making headlines – one from the UK (B1117), one from South Africa (501Y.V2) and one from Brazil (P1).
Why are they ‘significant’?
There is good evidence the UK strain is more transmissible and some evidence the other two may be too. On Friday, the UK government also said there was some as yet weak evidence to suggest the UK variant may also be more dangerous.
How much more dangerous might the UK variant be?
The government’s chief scientific officer, Sir Patrick Vallance, suggested it might increase the case fatality rate (CFR) by 30 percent. To put this in context, he said that out of 1,000 men in their 60s infected with the old variant, 10 would be expected to die, compared to 13 with the new variant. You can read the full study here.
Which is worse, a more transmissible virus or a more deadly one?
The maths of contagion is counter intuitive. A virus which is 50 per cent more transmissible will kill far more people than one which is 50 per cent more deadly as it infects so many more people.
Are all the new variants the same?
All share a remarkably similar set of mutations in the spike protein of the virus – the part which locks on to human cells – but they are not identical. All have arisen in areas where there have been sharp recent spikes in Covid cases.
Why have they popped up at the same time?
Scientists are not certain. It’s speculated that they are the product of common evolutionary pressures. One theory is that patients who have Covid for an extended period enable the virus to mutate more efficiently. The UK, South Africa and Brazil all have many such cases.
Can they evade vaccines?
Pfizer and AstraZeneca think their vaccines will still work against the UK variant. The jury is still out on the other two. There is some lab work that suggests the South African variant may end up evading existing antibodies (produced by vaccines or natural infection) some of the time. However, experts say it is unlikely a vaccine will suddenly stop working all together. It’s more likely they will become less effective by increments as the virus changes.
Is this pattern normal?
Yes, respiratory viruses tend to “drift” over time, and vaccines need to be constantly tweaked to keep up with them. This happens every year with the seasonal flu jab, for example.
How simple is the vaccine update process?
In theory it should be quite straightforward. As long as the changes that need to be made to vaccines are modest (just four or five changes to the more than 1,000 amino acids of the spike protein) then new vaccines can be produced quickly and without lengthy regulatory approval. The new RNA vaccines such as the one made by Pfizer can also be changed more quickly than conventional vaccines.
How will we know when vaccines need to be updated?
This is more complex. For flu there is a sophisticated global surveillance process in which new variants are spotted in advance and vaccines adjusted accordingly. This process is not yet in place for Sars-CoV-2. Covid is not yet tracked well globally and may not move in a predictable seasonal pattern like flu. As a new virus, it may also mutate less predictably.
Will closing borders help stop the spread of the new variants?
Closing borders completely is never a good move for a trading nation. North Korea is really the only country to have done it. On the other hand, good border checks and passenger testing and isolation policies like those operated from the outset by South Korea, Hong Kong and others in east Asia can limit the spread of new viruses. The trouble is they are resource intensive and require strong administrative competence and advance planning.
How far have the existing variants already spread?
The UK and South African variants have spread rapidly – the UK variant is now in more than 50 countries and the South African one has spread throughout the southern part of the continent. The Brazil variant has been detected in travellers to South Korea and Japan but is not thought to have spread widely beyond its borders.
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