The new variant of the Covid-19 virus first detected in India comes in three forms: B.1.617.1 (abbreviated as variant 1), B.1.617.2 (variant 2) and B.1.617.3 (variant 3). Each of these has a slightly different genetic makeup. The one that is surging in England is variant 2.

There is some good news and bad news about this variant, based on the limited data we have available. The good news is that we think it does not contain the 484K/Q mutation that has been linked to some degree of vaccine resistance. So the current AstraZeneca and Pfizer vaccines should work relatively well against it, and at least protect most of us from severe Covid-19 disease and death. We do not have any evidence of this variant causing more severe disease, either – at the moment.

The bad news is that we think all the Indian variants contain the L452R mutation, which is also found in the Californian variant, and which seems to confer some vaccine resistance and possibly more transmissibility. Variant 2 does seem to be spreading quickly in the English population – possibly more quickly than even the existing B.1.1.7 “Kent variant”. It also contains a new mutation, and we are not sure what this does yet – it may also be enhancing transmissibility.

What does this all mean, as England plans to open up further on 17 May and then 21 June? More data is required from laboratory and real-world population studies but in the meantime, you could think of it like this. Some virologists are fond of using the metaphor of an immunological landscape. Picture a savannah, with grassland, some hills, and a mountain in the distance. We are the prey – say, antelopes – while the virus takes the form of predators, like hyenas or lions.

If we are non-immune, you could see us as feeding on low-level grasslands. If the virus comes in a more rapidly spreading form (like the Kent or Indian variant), we could imagine this as a faster-moving predator chasing us down.

If we are vaccinated with at least one vaccine dose of a fairly effective vaccine (for instance, AstraZeneca or Pfizer) or have natural immunity, we might be standing on hills of different heights, depending on the effectiveness of our protective immune responses (and not everyone will respond to the vaccine). This makes it more difficult, though not impossible, for predators to catch us.

This analogy is not exact but may be quite useful at this time, in that not all antelopes chased by these predators will die; in fact, most of the time, the antelopes escape.

Most non-immune people in the UK will not be exposed to the virus at this time of low virus prevalence. And where such non-immune cases do get infected, most will only get mild Covid-19 disease (the equivalent of a few scratches and bites). All the Covid-19 vaccines are likely to prevent severe disease and death, though they may not protect you against mild or moderate disease.

However, new variants can always appear that may be able to bypass the vaccine or natural immunity barriers – unless we keep readjusting our Covid-19 vaccines (climbing higher hills) to keep out of their reach.

How can this analogy help us understand what may happen when we open up further on 17 May, as the Indian variant is surging across some areas of England – and when most under under-40s and some over-50s are not yet vaccinated?

If the Indian variant really is acting with enhanced transmissibility, then after 17 May we will have cheetahs chasing larger herds of antelopes across the grasslands (that is, non-immune under-40s) as we open up to indoor dining and other activities. Most of these antelopes will escape being eaten, though many will have some scratches and bites as they try to escape (equivalent to mostly self-limiting mild to moderate disease). This may take the form of long Covid, which is a risk unvaccinated young people will need to seriously consider in the coming weeks.

Some of these variant 2 cheetahs may have some hill-climbing capability (due to partial vaccine resistance with the L452R mutation), though again, most of the antelopes that are chased on the hills will still escape death, and just sustain some scratches and bites during their escape.

At the moment, it is too early to say if any mix-and-match vaccine combinations are so protective that they can put us up on the mountain top – out of reach of most of the current circulating vaccine variants. But clinical trials are continuing, and we may find an optimum combination, at least for a while – until the next variant comes along.

What does this mean, practically? Try to accelerate the vaccine programme to give at least one dose of the vaccine to all those who have not yet been vaccinated in the 18 to 50-year age group. Surge testing is unlikely to control this variant 2 virus, so masking and social distancing will need to be continued to reduce the spread of the virus as we improve first-dose vaccine coverage.

We know that with any rapidly spreading variant, there will be some more severe cases requiring hospitalisation, so we need to brace NHS teams for this – particularly as they are trying to catch up with all the non-Covid medical backlogs. If we really are following a “data, not dates” approach, unfortunately, we may have to consider delaying the proposed 17 May and 21 June relaxation dates – if the numbers of those requiring hospitalisation for more severe Covid-19 starts to rise too much.

This content first appear on the guardian

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