
In simple models the transmission parameter has two components: the number of contacts, and the chance of transmission if a contact is made. A âlockdownâ reduces the first of these, but itâs a pretty blunt instrument with dire economic consequences 2/n
As we emerge, the contact rate is not expected to revert to what it was before the pandemic hit. The first surge will have changed the sorts of contacts people make. Heightened awareness will likely make folks wary. Weâre not gonna flip back to March, but with better weather 3/n
People also behave differently in the summer. I donât think it will be enough to halt it, but this is (mostly) spread through droplets and sustained close contact. Poor ventilation helps the virus. A larger proportion of contacts happening outside will reduce transmission 4/n
It is also possible that very hot weather might force people indoors into air-conditioned space where they could make contacts. Iâm not an expert on the likely consequence of this, but hope my colleague @j_g_allen will weigh in on the risks involved 5/n
Masks are worn in many places. Itâs not totally clear what impact this will have, or whether there might be a tradeoff with people being overly confident and making more contacts. However if they reduce the chance of transmission, that will have a beneficial effect 6/n
This doesnât mean weâre done with this. There is not sufficient population immunity. Let's look at Sweden, which has been explicitly seeking that immunity through a light touch and fewer restrictions (though not none at all). 7/n
This reports that antibody testing of Stockholm residents shows only 7% of them have immunity. Thatâs at the cost of the largest number of deaths in Scandinavia so far. You won't get herd immunity until you reach about 60% https://www.reuters.com/article/us-health-coronavirus-sweden-strategy/swedish-antibody-study-shows-long-road-to-immunity-as-covid-19-toll-mounts-idUSKBN22W2YC 8/n
What it does mean is that the immediate future of the pandemic is unclear. What we should expect in outline is more disease, and more death. Local flare ups, and eventually larger outbreaks in population centers. But when exactly and where is not readily predictable. 9n
Even if the summer does slow the pandemic. We can expect as contacts resume that surges will build. We need to put testing in place to detect them. And we need to prepare for the fall when more time indoors will drive transmission up again https://www.theguardian.com/world/2020/may/20/exclusive-obama-us-national-stockpile-trump-coronavirus 10/n
When it does, we need to act prompt. This preprint estimates that delays in implementing controls in the initial surge cost tens of thousands of lives. This is not the least surprising. https://www.medrxiv.org/content/10.1101/2020.05.15.20103655v1.full.pdf 11/n
Stopping transmission earlier prevents more cases in the future. Alert readers will recall epidemiologists were saying this in early march. This is a mistake we shouldnât make again. We need testing. https://www.washingtonpost.com/outlook/2020/05/14/coronavirus-lockdowns-reopen-preparation/ 12/n
We need to report testing results clearly and straightforwardly. Mixing the results of virological and serological tests is wrong. It can create a false and misleading impression of the state of the pandemic. https://www.theatlantic.com/health/archive/2020/05/cdc-and-states-are-misreporting-covid-19-test-data-pennsylvania-georgia-texas/611935/ 13/n
And we need to be alert for the possibility of superspreading events. These have moved from conferences in big cities to workplaces in the heartland. Nowhere is immune. http://abc7amarillo.com/news/local/amarillo-area-has-2831-confirmed-covid-19-cases-2-additional-deaths-reported 14/n
The pandemic is not a storm that has passed as the outbreaks in the NE subside. It is still with us. To date its progress has been mostly influenced by human actions. Distancing measures had the desired effect. Whatâs next? Weâre going to find out whether we like it or not 15/end
and from @j_g_allen. Much appreciated! https://twitter.com/j_g_allen/status/1263594041444163589?s=20