very much agree with @BristOliver on this. just one point to add: if B.1.617 turns out to have a transmission advantage over B.1.117 (so R0 up by 50% say, to 6.5) I think we can deal with that with only minor course corrections. But if we lose more than 20% of the vaccine 1/2 https://twitter.com/BristOliver/status/1390572657431781378

... effect against transmission, that could cause some significant issues - even if there is no change in the vaccine's effect on serious disease / death. I haven't seen real evidence of 'vaccine escape', and if it stays that way (even with higher R0 for B.1.617) I'll be happy.