Heat and humidity probably slow down the transmission rate, but not enough to make large outbreaks impossible.
I could imagine that heat and humidity are especially beneficial for countries during the containment phase (esp. for contact tracing). According to this interview, the virus is inactivated at temperatures 30 degrees or higher. This could reduce the number of transmissions in setting that are particularly hard to contact trace (public transport, small grocery stores). As long as transmissions happen primarily in air-conditioned buildings or household contexts, contact tracing is much easier. (But perhaps it was doomed from the start, and the heat/humidity only meant it took longer to notice the cases that were being missed.)
Singapore and the Philippines seem very different to me in several respects!
The Philippines had reported 8 deaths by March 15th already. That’s indicative of a large undetected outbreak early on. I know almost nothing about how much testing they’ve done, but I could imagine that it’s not a lot. I could imagine that deaths in the Philippines are vastly underreported even now.
By contrast, Singapore definitely seemed to have their outbreak under control initially. I think there’s a good chance it could have worked with earlier border closures. They only closed borders on March 24th after several imported cases, primarily from Indonesia.
Indonesia (which also has had hot climate throughout recent events) has one of the highest deaths-to-confirmed-cases ratios worldwide, and that’s not factoring in that they may have missed >1,000 deaths already. According to that Reuters article, Indonesia had conducted only about 7,500 tests by April 3rd. By comparison, the UK conducted more tests on April 3rd itself (in a single day) even though its population is 3x lower than Indonesia’s. Experts had been saying all along that Indonesia not reporting any cases throughout February was extremely suspicious based on travel connections to Wuhan. It seems that they were spot on. I think it’s quite likely that Indonesia has >100,000 active cases by now. This suggests to me that dozens of Indonesians must have imported the virus to Singapore before the border closure (though maybe they all underwent temperature checks at the very least, and possibly quarantine?).
An alternative hypothesis (or contributing factor at the very least) is that containment failed because Singapore did not recommend mask usage as much as Hong Kong for instance did. Probably that was partly because of limited supplies, though the way it was communicated was similar to CDC communications (“masks don’t help unless you’re sick”). It seems increasingly likely to me that outbreaks are very hard to contain without widespread usage of masks (South Korea and Hong Kong rely heavily on mask usage – maybe someone could check up on the situation in Taiwan to get more data points on this).
Heat and humidity probably slow down the transmission rate, but not enough to make large outbreaks impossible.
I could imagine that heat and humidity are especially beneficial for countries during the containment phase (esp. for contact tracing). According to this interview, the virus is inactivated at temperatures 30 degrees or higher. This could reduce the number of transmissions in setting that are particularly hard to contact trace (public transport, small grocery stores). As long as transmissions happen primarily in air-conditioned buildings or household contexts, contact tracing is much easier. (But perhaps it was doomed from the start, and the heat/humidity only meant it took longer to notice the cases that were being missed.)
Singapore and the Philippines seem very different to me in several respects!
The Philippines had reported 8 deaths by March 15th already. That’s indicative of a large undetected outbreak early on. I know almost nothing about how much testing they’ve done, but I could imagine that it’s not a lot. I could imagine that deaths in the Philippines are vastly underreported even now.
By contrast, Singapore definitely seemed to have their outbreak under control initially. I think there’s a good chance it could have worked with earlier border closures. They only closed borders on March 24th after several imported cases, primarily from Indonesia.
Indonesia (which also has had hot climate throughout recent events) has one of the highest deaths-to-confirmed-cases ratios worldwide, and that’s not factoring in that they may have missed >1,000 deaths already. According to that Reuters article, Indonesia had conducted only about 7,500 tests by April 3rd. By comparison, the UK conducted more tests on April 3rd itself (in a single day) even though its population is 3x lower than Indonesia’s. Experts had been saying all along that Indonesia not reporting any cases throughout February was extremely suspicious based on travel connections to Wuhan. It seems that they were spot on. I think it’s quite likely that Indonesia has >100,000 active cases by now. This suggests to me that dozens of Indonesians must have imported the virus to Singapore before the border closure (though maybe they all underwent temperature checks at the very least, and possibly quarantine?).
An alternative hypothesis (or contributing factor at the very least) is that containment failed because Singapore did not recommend mask usage as much as Hong Kong for instance did. Probably that was partly because of limited supplies, though the way it was communicated was similar to CDC communications (“masks don’t help unless you’re sick”). It seems increasingly likely to me that outbreaks are very hard to contain without widespread usage of masks (South Korea and Hong Kong rely heavily on mask usage – maybe someone could check up on the situation in Taiwan to get more data points on this).