Thread by @sailorrooscout

A very encouraging study done on our mRNA vaccines! Pfizer and Moderna vaccines provided strong immune responses against variant B.1.351 first identified in South Africa in those who recovered from previous SARS-CoV-2 infections with a SINGLE dose.
medrxiv.org/content/10.110…

Individuals who were previously infected with SARS-CoV-2 displayed weak neutralizing activity not only against the original strain but variant B.1.351 as well (4-8 months post infection; remember antibodies from natural infection eventually wane over time). However, immunization

with a single dose of either mRNA vaccine elicited a robust antibody response that boosted neutralizing titers against the original strain by approximately 1000-FOLD. More importantly, vaccination elicited a robust neutralizing antibody response against B.1.351, although

neutralizing titers were significantly (2-3) fold lower than they were to the original variant. This means a couple of things. Firstly, it is more than apparent our vaccines can boost pre-existing antibody titers in previously infected individuals even to such a point they can

neutralize highly divergent neutralization-resistant viral variants such as B.1.351. Think of it as utilizing your natural antibodies as a primer and one dose as your booster! Therefore, we could justify use of one dose in recovered individuals if necessary. Secondly, the immense

polyclonal protection our vaccines provide is just nothing short of monumental. The image above displays neutralizing activities in serum from recovered COVID-19 donors prior to and following a single immunization with Pfizer’s or Moderna’s mRNA vaccine against the origin strain

and variant B.1.351. So if you needed some good news today, here is some to get you started! Remember what I said in a previous post of mine, 2-3 fold reduction does NOT mean the vaccines are 2-3x less effective as you can see. I can link some of my threads & other studies too!

In short, one dose of Moderna’s or Pfizer’s mRNA vaccines provided sufficient protection against variant B.1.351 in individuals who have suffered from previous SARS-CoV-2 infections thus utilizing antibodies produced via natural infection as a primer and 1st dose as a booster.