My hot take on Singapore vs. Hong Kong COVID responses is that in Hong Kong we cancelled school and we wear masks whereas in Singapore mask-wearing did not become de rigeur and they did not cancel school.

We both did similar (extremely large) amounts of testing. Neither of us did complete lockdowns. There;s a lot of cultural and demographic similarity too. We both go hit by similarly-sized 2nd waves of imported cases.

But in Hong Kong, effective R0 stayed pretty modest. In Singapore, however, they basically lost control and now have untraced local spread.

What's the difference? Their test-and-trace procedures and travel-restrictions are similar!

I think the difference is *probably* accountable to the two very obvious differences in how they've responded:

Masks and schools.

This goes back to my repeated point.

Once you've cancelled school you've achieved a HUGE amount of social distancing. Kids are major vectors even if they don't get very sick, and also this forces tons of parents to stay home.

But more than any of that, cancelling school creates a signal. It says, "THIS IS A BIG DEAL." It disrupts life for tons of families, forcing them to take notice. This sets off a chain reaction of unrelated behaviors; people adopt greater caution in the rest of their life.

Likewise, masks probably do actually reduce infection risk by reducing how much SARS-CoV-2 is being distributed around society.

But more than that, they serve as a social signal, reminding us all that these are unusual times demanding unusual precautions.

When walking outside without a mask gets you visibly negative responses from everyone you pass, you turn around, go back home, and put on a mask. And that makes you realize you shouldn't touch your face. Should wash hands. Shouldn't dilly-dally on your errands.