My understanding is we need about 80% vaccinated with the UK variant to reach herd immunity.
But with the Indian variant, I’m wondering if the herd immunity rate is closer to 90%.
Scientists in the U.K. now say that one of the variants from India, known as B.1.617.2, is highly contagious and likely more transmissible than the variant from the U.K., B.1.1.7.
“Transmission of this variant is currently faster than that of the B.1.1.7 variant,” the U.K.'s Scientific Advisory Group for Emergencies wrote Friday in a document. “It is a realistic possibility that it is as much as 50% more transmissible.”
If that’s correct, it would mean B.1.617.2 is 225% more transmissible than the original SARS-CoV-2 strains, and it would make B.1.617.2 the most contagious one on the planet.
Its disappointing. The UK variant out competed the original covid, now the Indian variant may outcompete the UK variant. Maybe the best we can hope for is a world where almost everyone gets infected, but vaccines keep the illnesses mild
Depends on how effective the vaccine is against that variant doesn’t it? Maybe I missed it, but I didn’t see a definitive statement about that in the links. And ‘boosters’ are being developed to deal with variants that may pop up.
For ‘herd immunity’ to work the vaccine has to stop vaccinated people from becoming infected with a transmissible form of the virus, if not then anybody not vaccinated is always in danger. And vaccinations may need to continue for everybody else over time in order to remain ‘immune’.
*Noting that ‘herd immunity’ and ‘immune’ are not being used with very specific definitions in a lot of discussion about this topic.
Well, this for me is why the CDC move yesterday is so dubious. Obviously as you note we are nowhere near herd immunity even with the existing strains, and the new strains put this goal further out of reach. We do have good data that the existing vaccines are virtually 100% effective at preventing any serious consequences from the early strains, and that’s the ostensible evidence justifying the CDC move. So great - let’s all forget about masking and social distancing now, because now only foolish people who refuse to get vaccinated will get seriously ill or die? No, even if you accept that approach to unvaccinated people, it’s nowhere near that simple.
(a) Not everyone who wants to get vaccinated has yet been fully immunized;
(b) We don’t yet have reliable data on whether the vaccination breakthrough rate for serious disease with the new variants might be higher;
(c) We can almost certainly rectify that problem with modified mRNA boosters, but it will be months before they are widely administered;
(d) A continuing high rate of community transmission may in the short term only seriously harm the unvaccinated, but a large reservoir will inevitably lead to the spread of variants that may harm everyone, and creates greater potential for further mutation.
Keep in mind, vaccination isn’t the only way to achieve herd immunity. The question was never one of whether we’d achieve herd immunity, but just how we would do it. Vaccination is a much better way to achieve herd immunity than just letting the epidemic run its course, of course, but we’ll still get there eventually. And achieving herd immunity with, say, 80% of the populace vaccinated and 10% getting infected might not be as good as getting it by 90% of the populace being vaccinated, but it’s a lot better than achieving it by 90% of the populace getting infected.
True enough. From that macabre perspective, the Indian variant is a quicker path to herd immunity. Steepen the curve… remember not so long ago that was advocated by a minority as a viable policy?
Although this is not quite so black and white. It depends on how adaptable the virus proves to be, how robust and durable the immune response to infection turns out to be, and the long term dynamics of our policy response and behavior. We have never reached (and will never reach) herd immunity to all influenza strains, though we may have it transiently in some populations to some strains.
From the NPR article
Of course, there are several caveats here. The findings are preliminary and haven’t been published, except on Twitter.
When I do literature searches at work, I’m not allowed to use Twitter as a source…