The Evolving SARS-CoV-2 Genome

first published : 14.03.2021

Which SARS-CoV-2 variants are more likely to evade vaccine response/ effectiveness?

By now several preliminary data / reports has shown that the ‘varaints of concern’ of SARS-CoV-2 can partially evade the SARS-CoV-2 wild-type spike-protein (early SARS-CoV-2 sequences) based vaccines. With the ‘varaints of concern’ now being also the dominant varaint in several European countries, it is a major challenge to understand which varaints would evade the current available vaccines. Moreover, if the evasion is ‘remarkable and widespread’, it would make the current vaccination futile.

Here we look at the latest (first published 12.03.2021, CELL) ‘lab based’ data (neutralization assay) from various varaints against the sera from Pfizer-BioNTech or Moderna COVID-19 vaccinated patients. Here we see only the data for SARS-CoV-2 UK variant (B.1.1.7, most doninant varaint in Luxembourg), South African vairant (B.1.351, second most doninant varaint in Luxembourg) and Brazilian varaint (P.1, only 2 cases detected so far).

Please note that the data is normalized to wild-type (previous circulating lineages) where vaccine neutralization is equivalent to 100% and does not mean 100% of WT for Pfizer-BioNTech and Moderna COVID-19 vaccine effectiveness is equivalent, but only intended to show relative effectiveness against the different variants. Also, the vaccination data is post 2X doses. For detailed method, please read the original research article.

So, from the above assays it is likely that irrespective of individual efectiveness of mRNA based vaccines, the current lot from Pfizer-BioNTech and Moderna would be less effective against B.1.1.7 and P.1 and least effective against B.1.351.

Another recent study (published 20.03.2021, CELL) which also shows that the variants B.351 and P.1 escapes neutralizing antibodies (over 5 folds) compared to B.1.1.7 (1.7 folds).

What to expect next?

This is the big question ahead for sure and here are some broad possible repurcassions:

  • The UK varaint (B.1.1.7) is currently the dominating varaint in Luxembourg (as well as in several European countries) but with more vaccinations ahead, the South African varaint (B.1.351) and Brazilian varaint (P.1) would slowly become the dominant variants (as it could still transmit through vaccinated people more effectively), or other varaints which have even higher rate of evasion.
  • Even if the current vaccination roll-out reaches a majority of adults across the whole EU by year-end, the number of new cases and hospitalizations would keep fluctuating (but not going away anytime soon).
  • Unless a highly coordinated global vaccination effort is undertaken against all major varaints simultaneously, there would always be a risk for new variants skipping the available vaccinations and prolonging the pandemic.
  • It is quite likely that eventually a ‘cocktail’ of vaccines would be needed rather than individual solutions (from different pharmapeutical companies), but how and when such effort would happen would depend on the severity of the new varaints.

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