Tuesday, August 03, 2021

Is There A Way To Prevent The Emergence Of Vaccine-Resistant Variants?

Could a combination of vaccinations and non-pharmaceutical/behavioural interventions that decrease viral transmission rates be used to decrease the risk that new problematic COVID-19 variants will emerge?

First, what their objective was, from the Introduction to the paper:
...(T)o our knowledge, the interplay of the population vaccination rate with the stochastic dynamics of emergence of a resistant strain has been discussed, but not formally modeled. Specifically, a concern is whether a combination of vaccination and transmission rates can create positive selection pressure on the emergence and establishment of resistant strains. To address this issue, we implemented a model to simulate the probability of emergence of a resistant strain as a function of vaccination rates and changes in the rate of virus transmission, resembling those caused by non-pharmaceutical interventions and behavioural changes...

Second, what they found, from the Abstract of the paper:
...We found that a fast rate of vaccination decreases the probability of emergence of a resistant strain. Counterintuitively, when a relaxation of non-pharmaceutical interventions happened at a time when most individuals of the population have already been vaccinated the probability of emergence of a resistant strain was greatly increased. Consequently, we show that a period of transmission reduction close to the end of the vaccination campaign can substantially reduce the probability of resistant strain establishment...

So, assuming their modelling has validity, what would be the recommendation for policy makers?

Here's what the authors had to say about that in the Discussion of the paper:
...One simple specific recommendation is to keep transmission low even when a large fraction of the population has been vaccinated by implementing acute non-pharmaceutical interventions (i.e. strict adherence to social distancing) for a reasonable period of time, to allow emergent lineages of resistant strains to go extinct through stochastic genetic drift..."


Even the best models are just that.

However, why not err on the side of caution?

Of course, unlike the U.S. where the real world experiment currently being carried out is one based, to a large degree, on differences in vaccination rates, here in Canada we may soon be doing our own real world experiment that is instead based on differences in non-pharm/behavioural interventions.



Danneau said...

Unfortunately, it looks like an uphill slog because, y'know, the economy, tourism is suffering, and we have to get back to some semblance of normalcy and the cruise ship industry seems to be leading the writing of public health policy. A goodly number of our leaders belong with Tom Lehrer's Hen3ry in the Massachusetts Home For The Bewildered.

NVG said...

Rayne, over at EmptyWheel, has a word of warning for Un-Vaxxed Men


Color me highly skeptical.

Anti-vaxx/COVID-hoax/Anti-Mask men have studiously ignored science throughout the pandemic, including 15 months of published research about the risk COVID poses to their ‘nads.

I wrote last September about the risks to men’s reproductive organs:

Autopsies of COVID-19 victims showed damage to testicles:

e.a.f. said...

NVG, well if those men don't care about their testicles, its just as well, perhaps they will fail to reproduce and we won't have as many people who are plan old stupid. On the down side they may pass COVID on to children who can't be vaccinated yet due to their young ages.