Thread by @sailorrooscout

It is a GREAT morning when you find studies that can help put to rest concerns about AY.4.2, B.1.617.2+E484K, AY.1, AY.2 (or rather “Delta-Plus” in general) Lambda, B.1.1.519, A.30, Mu and so much more.

When I say the vaccines can handle variants I mean it. Working on a thread.

A recent study out Denmark shows a sublineage of the Delta variant, AY.4.2, was NOT more resistant to neutralization relative to other circulating Delta lineages or sublineages AND showed ONLY a MODEST 2.3-fold reduction in neutralization.

Let’s talk about that and more!

AY.4.2 recently accounted for an increase proportion of Delta cases in United Kingdom (UK), Romania, Poland, and Denmark. Here, researchers evaluated the sensitivity of AY.4.2 to neutralization by sera from Pfizer recipients. AY.4.2 was NOT more resistant to neutralization

relative to other circulating Delta lineages or sublineages and showed only a modest 2.3-fold reduction in neutralization relative to the vaccine strain. While the rarer B.1.617.2+E484K variant showed a 4.2-fold reduction in neutralization which warrants

surveillance of strains with the acquired E484K mutation, this variant was still successfully neutralized by the vaccines (for some perspective, this is a lesser fold-reduction in neutralization than Beta or B.1.351). You can find this study here: medrxiv.org/content/10.110…

Next up is A.30. You might have heard about this one from: nature.com/articles/s4142…. What you need to know is this is NOT a new variant and this study looked at samples from this past Spring. The last sample was collected in Sweden in May and this variant has essentially

“burned out.” Lastly, based on neutralization titers here, the vaccines would still be above the protective threshold even if it was circulating widely, but it isn’t and hasn’t been for a while. Keep in mind this study also used pseudoviruses which tend to vary in results.

Remember Mu? B.2.621? Mu isn’t vaccine resistant either and didn’t seem to be able to compete with Delta. Fold-reduction in LIVE VIRUS studies was less that than of Beta, Gamma and Delta. This is around a 2-fold reduction. You can find that study here: icpcovid.com/sites/default/…

Last up we have a study out of the University of Texas that looked at Pfizer-Elicited Neutralization of Delta Plus, Lambda, and Other Variants. Those other variants being USA-WA1/2020 SARS-CoV-2 bearing variant spikes from Delta plus (Delta-AY.1, Delta-AY.2), Delta- 144

(Delta with the Y144 deletion of the Alpha variant), Lambda, and B.1.1.519 lineage viruses. Results? ALL sera neutralized the variant viruses to titers of >80. Their conclusion? “The susceptibility of Delta plus, Lambda, and other variants to neutralization by the sera indicates

that antigenic change HAS NOT led to virus escape from vaccine-elicited neutralizing antibodies and supports ongoing mass immunization with BNT162b2 to control the variants and to minimize the emergence of new variants.” You can find this study here: biorxiv.org/content/10.110….

So why aren’t we getting Delta specific boosters right now? I recommend this article here which explains why in detail: vox.com/future-perfect….

“Vaccines not only decrease transmission rates, but also decrease disease severity among individuals who do acquire infection. Vaccinated people with breakthrough infections, INCLUDING infection with the Delta variant, are less likely to develop symptoms, less likely to develop

severe symptoms, more likely to recover from their illness quickly, and much less likely to require hospitalization compared with unvaccinated people.” You can read this here: jamanetwork.com/journals/jama/… and read more here: bmj.com/content/374/bm…