Thread by @AdamJKucharski

Preliminary UK data on vaccine effectiveness against B.1.617.2 (originally detected in India) now available: khub.net/documents/1359…. A few things to note... 1/

First and foremost, it’s another reminder that *second doses matter*. By Aug/Sep, UK will be in much better position against B.1.617.2, but there’s a risk of substantial transmission in meantime as things reopen. 2/

https://twitter.com/AdamJKucharski/status/1393260065747001344?s=20

Also remember that when vaccine effectiveness high, small absolute differences can have big effect. E.g. a drop from 95% to 90% would double number at risk (and probably more than double outbreak size given non-linear nature of transmission). 3/

However, confidence intervals wide because early data - don’t put too much weight on single numbers. Worth keeping an eye on other data too (like below for pre-B.1.617.2 period), so can compare age patterns etc. and protection against severe outcomes: gov.uk/government/pub… 4/

Above also highlights importance of good data. The B.1.617.2 analysis used almost 13,000 sequences linked to vaccine status - which means it’s crucial to support global research efforts so we don’t have to wait until problems reach UK for these insights 5/ theguardian.com/global-develop…

Finally, evolutionary dynamics of other coronaviruses (journals.plos.org/plospathogens/…) suggest we are going to face new variants for foreseeable future. But vaccines will make huge difference in reducing risk, so let’s make sure the world has access to them: bbc.com/news/world-571… 6/6