Thread by @DrEricDing

NO BLOOD CLOT RISK—In new AstraZeneca #COVIDVaccine trial in the US, Peru, and Chile:

➡️ No effects on blood clots observed in the 21,583 who were vaccinated, even with 60% of the people having some type of co-morbidity.

Really reassuring! 🧵 #COVID19
astrazeneca.com/media-centre/p…

2) 79% efficacy for symptomatic #COVID19 overall—100% efficacy for severe disease is amazing.

Even better - 80% efficacy in elderly. That’s super good that efficacy didn’t drop in the elderly. (In contrast, natural infection’s protection against reinfection plummets in elderly)

3) “This AstraZeneca-led US Phase III trial included two doses administered at a four week interval. Previous trials have shown that an extended interval of up to 12 weeks demonstrated greater efficacy, which was also supported by immunogenicity data...”

4) “This evidence suggests administration of the second dose with an interval longer than four weeks could further increase efficacy and accelerates the number of people who can receive their first dose.”

➡️ this supports earlier UK trial findings that a delayed 2nd dose is okay

5) There is evidence to show that vaccine efficacy of Oxford AstraZeneca vaccine improves with longer time gap between the first and second shots. 10-12 weeks seems to the the sweet spot—although it looks like it goes up longer, the 95% confidence interval gets wider >13 weeks.

6) Here is the full study on the earlier 12 week AstraZeneca booster delay study. Note this is based on UK and South Africa trials, not the new US/Peru/Chile trial out today.

https://twitter.com/drericding/status/1367798304428396546