Thread by @vipintukur

Is #Omicron more likely than #Delta to cause infections in vaccinated persons?

The study found that the positivity rate among unvaccinated persons was higher for Delta (5.2%) than Omicron (4.5%).

They found similar results in persons who received a single vaccine dose 1/

Conversely, the Omicron had higher positivity rates than Delta among those who received two doses within 5 months (Omicron = 4.7% vs. Delta = 2.6%), two doses >5 months ago (4.2% vs. 2.9%), & three vaccine doses (2.2% vs. 0.9%). 2/

Omicron positivity rates in persons receiving one or two vaccine doses were not significantly lower than unvaccinated persons but were 49.7% lower after three doses. 3/

In comparison, the reduction in Delta positivity rates from unvaccinated to 2 vaccine doses was 45.6-49.6% and to 3 vaccine doses was 83.2%. 4/

Despite the higher positivity rates for Omicron in vaccinated persons, 91.2% of the Omicron infections occurred in persons who were eligible for 1 or more vaccine doses at the time of PCR testing. 5/

In summary:

➡️ Omicron is more likely than Delta to cause infections in vaccinated individuals

➡️ Omicron infection rates did not significantly reduced until 3 vaccine doses

➡️ Still, most Omicron infections occurred in persons eligible for addition vaccine doses. 6/

Here is the link of the preprint 👇

medrxiv.org/content/10.110…

And the detailed thread on the same 👇

https://twitter.com/nathangrubaugh/status/1486183124409233411?s=21