On COVID-19 Variants: 3 February 2020

There is a reason that you don’t hear about  new COVID-19 variant strains arising from Japan, or New Zealand, or South Korea – and this is because the spread of coronavirus in these regions has been contained. Mutations (or variations) arise as a natural by-product of viral replication due to errors made in the synthesis of the virus’ genome. Those errors that confer a competitive advantage – whether it be in replication, transmission or evasion of host immunity – will increase in frequency in the population if given enough time.

But consider a population where viral transmission has essentially been halted – as has occurred in the countries above due to careful public health mitigation efforts. In such an environment, a new variant simply could not take hold. But, in countries where adherence to public health guidelines has been more lax, a new competitively advantageous variant could take hold.  This is indeed the case of lineage B.1.1.7 which has quickly throughout the southeast of England during a time when COVID-19 cases were widespread in the country. The fact that this variant has preferentially established itself strongly suggests “natural selection of a virus that is more transmissible at a population level” (link: https://jamanetwork.com/journals/jama/fullarticle/2775006).

A second coronavirus variant first detected in South Africa, known as B.1.351, has already spread to more than 30 countries. This particular variant has potential to “escape” protection from current vaccines, meaning vaccines might not stop people from getting infected with COVID-19. In fact, studies by Moderna have indicated that a “six-fold reduction in neutralizing titers was observed with the B.1.351 variant relative to prior variants” (link: https://investors.modernatx.com/news-releases/news-release-details/moderna-covid-19-vaccine-retains-neutralizing-activity-against). Despite this reduction, Moderna writes that these antibody levels do remain above thresholds that are expected to be protective. A similar effect was seen with the Pfizer vaccine as well (link: https://www.biorxiv.org/content/10.1101/2021.01.25.428137v2).

The full extent and impact of these COVID-19 impacts in the US pandemic might never be known because, as a country, we do very little in the way of genetic epidemiologic surveillance (link: https://www.vox.com/science-and-health/22225012/us-sequencing-covid-19-variants).  This is in stark contrast to other countries like the UK who have made large financial investments in the infrastructure needed to identify, track and react to viral variants. In Los Angeles County only a few dozen or so samples are sequenced daily, this out of >80,000 daily tests (link: https://deadline.com/2021/02/california-identifies-over-1000-cases-of-west-coast-covid-19-variants-1234685746/)

The process by which we can eliminate the impact of these new variants is no mystery – but are part of established public health practices which we have largely been unwilling to implement. A renewed emphasis on physical distancing and masking will slow the spread of variants, even if more transmissible. Specifically, making N95 masks widely available to those who cannot avoid congregate settings (essential workers for example) might be particularly useful. Widespread testing and tracing with specific identification of more infectious isolates could focus public health resources on harder hit regions – but again, we have shown little appetite to do such detailed work.

Finally, and most importantly, vaccination will reduce the susceptible population and also prevent further viral spread.  Thus far, available vaccines do appear to be effective against these new circulating strains – at least for the time being.  But continued delays and lack of access to vaccines could certainly derail the small progressive gains we have made thus far.

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