When I look at the numbers of Covid-19 cases and Covid-19 deaths among G20 countries, India still has a relatively low number per capita. The arguments for why the current wave is particularly catastrophical in India (like population density or poverty) applied all the time, however, except for the mutation. How did India manage to have relatively low case rates up to now?
Masks probably work well for less contagious variants and other respiratory diseases such as influenza, but after a certain threshold of contagiousness is reached, they don't.
This is why elastomeric respirators should be used during pandemics rather than masks.
The loosening of restrictions on gatherings might also be to blame.
In Zvi's last post, the comment thread includes data on the B.1.617, which seems to have cracked the contagiousness code in India. https://www.lesswrong.com/posts/4PTstS4Kt5hBMJTRL/covid-4-22-crisis-in-india?commentId=KQmoQRgHa2Qd2gJiz