Thread by @celinegounder

1/ Here's why it's important to get that 2nd dose of COVID vaccine:

B.1.1.7 UK variant
- 1 dose of Pfizer 49% effective vs symptomatic COVID
- 2 doses 93% effective

B.1617.2 India variant
- 1 dose of Pfizer 33% effective vs symptomatic COVID
- 2 doses 88% effective

2/ See Table 2:
khub.net/documents/1359…

3/ This is why the UK has reduced the interval between 1st and 2nd doses from 12 weeks to 8 weeks for persons over 50 and others at high-risk for severe disease:
reuters.com/world/uk/engla…

4/ The UK may be entering 3rd wave of COVID:
theguardian.com/world/2021/may…
Is this because of the B.1.617.2 India variant?
Vaccination rates:
- UK: 38% fully vaxx'ed, 59% 1st dose
- USA: 51% fully vaxx'ed, 41% 1st dose
Will UK dose delay strategy turn out to be the right one?

5/ For those of you asking about J&J vs B.1.617.2, I haven't yet seen data on that.
There is data for the AstraZeneca vaccine, which is an adenovirus vector vaccine like the J&J vaccine and is being used in India and the UK. The AZ vaccine is a 2-dose vaccine while J&J is 1-dose.

6/ Vaccine effectiveness of AstraZeneca vaccine:
See Table 2: khub.net/documents/1359…

B.1.1.7 UK variant
- 1 dose of AZ 51% effective vs symptomatic COVID
- 2 doses 66% effective

B.1617.2 India variant
- 1 dose of AZ 33% effective vs symptomatic COVID
- 2 doses 60% effective

7/ In contrast to Pfizer & Moderna vaccines, the J&J vaccine was the only one "stress-tested" vs variants in Phase III clinical trials.
It's one of the reasons it looked "less good."
J&J was tested vs P.1 variant in Latin America & B.1.351 variant in South Africa.