Corona Daily 216: B.1.1.7 – Three Questions

‘Variant of concern’ is not a descriptor of our feelings, but one of the working names of B.1.1.7. When a new, different strain is found such as in the UK, South Africa or today in Japan, scientists ask three critical questions. (a) Is the variant more transmissible? (b) is it more deadly, more severe? (c) Can it bypass vaccines?

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On transmissibility, there is no doubt. Scientists initially estimated it was 70% more transmissible, but the latest modelling puts it at 56% higher. When R-zero, the reproductive number is 1, an infected person on average passes it to one other person. The pandemic grows when R0 is greater than one, declines when below 1. British researchers estimate that during lockdown, coronaviruses other than the B.1.1.7 variant have R0 at 0.95. The reproductive number of B.1.1.7 is 1.45. Genetic sequence traced it back to 20 September in Kent, another case in Greater London the following day. By now, 45 countries have confirmed existence of cases with this variant.

One theory for the rapid spread is that the variant has a heightened viral load, a higher concentration of the virus in the upper respiratory tract. Until now, this theory is not backed by credible data.

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Scientists have said B.1.17 spreads faster, but it is neither more deadly, more damaging or more severe. Presenting this fact as good news is misleading for two reasons.

First, there is a clearly established sequence: cases – hospitalizations – deaths. The more the cases, more patients get admitted and a certain proportion dies. By spreading faster, the new variant infects some vulnerable people who would be safe in a less transmissible variant. As ICU beds reach capacity and the health care system gets overwhelmed, non-covid patients are unable to treat their ailments or get operated. That increases the toll. The excess mortality tracker shows the total pandemic-related casualty figures.

Second, mathematically a more deadly virus does less damage than a more transmissible virus. Professor Kucharski takes a realistic scenario, where the reproduction rate is 1.1, fatality risk 0.8% and 10,000 active infections. With those numbers, we expect 129 deaths in a month. If fatality rate increases by 50%, that leads to 193 deaths. On the other hand, a 50% increase in transmissibility causes a shocking 978 deaths in just one month.

A more deadly variant can be tragic for an infected individual, that person may not survive. But the rapidly spreading variant is tragic for society. By spreading faster, it manages to kill far more people. (This is because a small % of a large number can be much bigger than a big % of a small number.)

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The third question is if it can bypass vaccination.

Here we have some truly good news. The consensus among the scientists is that the vaccines will work against this variant. One virologist compares the vaccine to a thousand big guns pointed at the virus. Even with the 23 mutations, it is not easy for the virus to find a genetic solution to combat all the antibody specificities and the overall immune response.  

Viruses like influenza amass mutations relatively quickly. But others, such as the measles virus, are stable over a long time. Even the influenza virus needs five to seven years to collect enough mutations to escape immune recognition.

Despite the growing spread across the world, the covid virus can still attack armies of uninfected people. That is why it has no reason currently to do anything spectacular. At will, it is able to find new hosts for it to enter and multiply. So, it is felt that the coronavirus is not yet interested in developing anti-vaccine weapons of its own. However, once enough people are vaccinated, the virus may evolve into an incarnation that will bypass the vaccine.

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In short, B.1.1.7 spreads faster. Though not inherently more deadly, its impact on the countries and the world is more deadly because of the faster spread. Currently, it is understood that vaccines can protect us against this variant. That comfort is available until such point when there are too many people vaccinated for the coronavirus’s comfort.

Ravi