Note: I’m taking a few days off from the daily Q&A.  Will resume on 1 June.  In the meantime, please keep sending your questions!

Question: Are vaccines effective against the variants arising out of India?

Answer: We talked about this issue in our Q&A of 4/22.  Since then, we have more data adding to the evidence-base that vaccines are effective against the B.1.617 variant (and sub-lineages).  Earlier this week, Public Health England issued a press release describing results of its recent research, “Vaccines highly effective against B.1.617.2 variant after 2 doses.”  The study, which is still in pre-print (e.g. not yet peer reviewed), compared vaccine effectiveness based on variant type (B.1.1.7 originally discovered in the UK and B.1.617.2 originally discovered in India).  Findings indicate that:

1. For fully vaccinated individuals, both Pfizer and Astra-Zeneca are effective at preventing symptomatic infection from B.1.1.7 and B.1.617.2 variants. 
2. Effectiveness against symptomatic disease is slightly reduced with the B.1.617.2 variant.  Two or more weeks after the second dose:
   • Pfizer was 88% (95% CI: 78% to 93%) effective against the B.1.617.2 variant; 93% (95% CI: 90% to 95%) effective against the B.1.1.7 variant
   • AstraZeneca was 60% (95% CI: 29% to 77%) effective against the B.1.617.2 variant; 66%  (95% CI: 54% to 74%) effective against the B.1.1.7 variant
3. Effectiveness after just one dose is greatly reduced with the B.1.617.2 variant: After only one dose, both vaccines were 33% effective against symptomatic disease from B.1.617.2 variant, compared to around 50% effective against the B.1.1.7 variant