Céline Gounder, MD, ScM, FIDSA 🇺🇦 Profile picture
Medicine / Infectious Disease / Epidemiology / @KFF @CBSNews @NYUGrossman @BellevueHosp doc / Threads @drcelinegounder / Bluesky @celinegounder.com

Jul 8, 2021, 8 tweets

1/ New data in the last day on how well natural immunity and vaccine-induced immunity protect us against the Delta variant.

Here's the take-home message:
2 doses of Pfizer or Moderna vaccine will protect you,
even against the Delta variant.

2/ Published in the @NEJM
nejm.org/doi/full/10.10…

Delta is 2.4-3.3x less susceptible to neutralizing Abs elicited by prior infection or Pfizer/Moderna vaccination as compared to the early WA1/2020 variant.

The dotted line represents protective immunity.

3/ Published in @Nature:
nature.com/articles/s4158…

Left:
Low neutralizing antibody (nAbs) levels by 12 months after natural infection
4x decrease in nAbs vs Beta & Delta compared to Alpha

Right:
Dramatic bump in nAbs levels if vaccinated after infection, including vs Beta & Delta

4/ nature.com/articles/s4158…

Left: nAbs 3 weeks after Pfizer

Right: nAbs 8 weeks after Pfizer (i.e. 5 weeks after 2nd dose)

You need the second dose to assure neutralization versus Beta & Delta.

The dotted line represents limits of detection.

5/ nature.com/articles/s4158…

12m after infection:
50% neutralizers vs Beta variant
47% neutralizers vs Delta variant

12m after infection + vaccination:
100% neutralizers vs all variants

Natural infection alone doesn't protect vs variants.
mRNA vaccination after infection does.

6/ nature.com/articles/s4158…

Week 3 after Pfizer vaccine (just prior to 2nd dose):
6% neutralize Beta
13% neutralize Delta

Week 8 after Pfizer vaccine (5 weeks after 2nd dose):
81% neutralize Beta
94% neutralize Delta

7/ Immunity is NOT on/off.

8/ Immunity is on a spectrum or gradient.

nAbs = neutralizing antibodies

We can overcome immune-evading variants (e.g. the Beta & Delta variants) with higher nAbs titers.

This is why you need to be vaccinated—even if you've had COVID—if you want to be protected vs variants.

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