Thread by @DrTomFrieden

Delta’s sharp rise in the UK and Israel presaged the large wave we’re facing in the US. But in key ways, our epidemic curve looks different. I’ll explain how it’s different, why, and what this tells us about the future of the pandemic. 1/thread

In the US, we haven’t tested at nearly the rate of the UK and Israel. We test at less than one third their rate of testing. Because of this, we have likely missed A LOT more cases. 2/

This may explain why our curve doesn’t go quite as high as Israel’s or the UK’s. The number of actual infections is likely much higher (at least 3X, maybe more than 5X) than the number of reported cases in the US. 3/

Our high test positivity rate is another indication that testing in the US is insufficient. The US positivity rate is 3-4X higher than the rates in Israel and the UK. ID and IA have close to 40% (!) test positivity. Unbelievable. bit.ly/3yLTHVm 4/

The US has more unvaccinated people. The UK has fully vaccinated 63% of their population. Israel has fully vaccinated 62.5%. The US? 51.9%. If the US had continued on the trend it had until June, we’d have a much higher vaccination rate. Slower vaccinations mean more deaths. 5/

Two reasons our hospitalization and death rates are higher: More true cases (even though we have lower reported cases because of insufficient testing), and more unvaccinated people. 6/

We’ve also vaccinated a lower proportion of older adults, who are much more vulnerable to severe illness and death from Covid. nyti.ms/2WTKEEC 7/

Delta became dominant earlier in the UK and Israel and its spread has been carefully monitored by their disease surveillance systems. Their experiences serve as a warning for other countries. Even after sharp drops, cases climbed again with reopening. 8/

Opening schools and keeping them open is, after reducing deaths from Covid, the most important challenge facing the US and many countries. Places that open without a comprehensive approach may need to close, or risk their students’ and staff’s health. bit.ly/38GnTq1 9/

The fundamental lesson of Delta isn’t the need for boosters, it’s the need for a multilayered approach to fighting Covid—the bedrock of which is vaccines. 10/

That means: Masking up, preventing and interrupting superspreading, improving ventilation, improving detection of cases, and upping our support for patients and their contacts. 11/

We can’t predict the future with confidence. But the virus has adapted and will continue to adapt. Unless we adapt too, what goes down can go back up. We underestimate the virus at our peril. 12/end