Thread by @DrEricDing

BREAKING—analysis of Russian #SARSCoV2 vaccine’s phase 3 trial with ~ 20,000 participants finds that a 2-dose regimen has an efficacy of 91.6% against symptomatic #COVID19. No serious adverse events were deemed to be associated with vaccination. 100% efficacy for severe illness.

2) The benefits of the vaccine diverged from placebo around day ~18 after the first shot.

Estimated vaccine efficacy occurring at any time after dose 1 was 73·1% (95% CI 63·7–80·1). Notably, in vaccine group, most cases of #COVID19 occurred before dose 2
thelancet.com/journals/lance…

3) Notably, vaccine efficacy was 91·8% (67·1–98·3) in participants older than 60 years.

There were no cases (vaccine group) and 20 cases (placebo group) of moderate or severe COVID-19 confirmed at least 21 days after dose 1

4) From 15 to 21 days after the first dose, efficacy was 73·6% (p=0·048), then from day 21, efficacy was 100% (p<0·0001; appendix p 11).

5) presence of antibodies specific to the receptor-binding domain of SARS-CoV-2 42 days from the start of vaccination: In the vaccine group, RBD-specific IgG was detected in 336 (98%) of 342 samples—an antibody seroconversion rate of 98.25% in vaccinated!

6) serum samples from 100 participants were analysed for the presence of **neutralizing antibodies** on day 42 after first vaccination (figure 3B)—the neutralizing antibody seroconversion level was 95.83% in the vaccine group!

7) Sputnik V vaccine is a two-dose adenoviral vector vaccine using *two different adenoviruses* for each dose, administered 21 days apart. an adenovirus is altered so that it can deliver gene for spike protein. It's an similar to vaccines by AZ and J&J.
cnn.com/2021/02/02/hea…

8) But... The authors say that using a different adenovirus vector for the booster vaccination may help create a more powerful immune response. That’s what 🇷🇺 vaccine did.

Oxford / AZ meanwhile used same adenovirus for both first and second doses. That might explain somewhat.

9) One advantage of adenoviral vaccines is that they do not need to be stored and transported in extremely cold temperatures, scientists say. Sputnik V costs roughly $10 per dose, says CNN piece.

10) Time to update the table — another 15,000 vaccinated in Sputnik V trial with zero deaths.

https://twitter.com/drericding/status/1356080282286379010

11) Here is meantime the new Oxford-AZ vaccine report for 1 dose efficacy starting day 22–which found 76% for symptomatic #COVID19. See 🧵 for details.

https://twitter.com/drericding/status/1356743346543329284

12) I would next like to see data in the Russian Sputnik V vaccine and effects on pregnancy and if antibodies carry over into infants to protect them like this study did.

https://twitter.com/drericding/status/1356063288006684672