Via Nature Communications, a shocking report: Swift and extensive Omicron outbreak in China after sudden exit from ‘zero-COVID’ policy. The abstract, with my bolding, and then a comment:
In late 2022, China transitioned from a strict ‘zero-COVID’ policy to rapidly abandoning nearly all interventions and data reporting. This raised great concern about the presumably-rapid but unreported spread of the SARS-CoV-2 Omicron variant in a very large population of very low pre-existing immunity.
By modeling a combination of case count and survey data, we show that Omicron spread extremely rapidly, at a rate of 0.42/day (95% credibility interval: [0.35, 0.51]/day), translating to an epidemic doubling time of 1.6 days ([1.6, 2.0] days) after the full exit from zero-COVID on Dec. 7, 2022. Consequently, we estimate that the vast majority of the population (97% [95%, 99%], sensitivity analysis lower limit of 90%) was infected during December, with the nation-wide epidemic peaking on Dec. 23.
Overall, our results highlight the extremely high transmissibility of the variant and the importance of proper design of intervention exit strategies to avoid large infection waves.
In the discussion section of the report, the authors write:
With an infection fatality ratio between 0.1 and 0.2% for the Omicron variant, we would expect between 1.3 and 2.6 million COVID-19 deaths in China during Dec. 2022 as well as Jan. 2023 (because of the delay from infection to death).
And that is with a case fatality rate of 0.1-0.2 percent. So 1.37 billion people in China contracted the Omicron strain of SARS-CoV-2 in December 2022, and at least one or two in a thousand died of it. The government saw it coming because Omicron was already spreading, and dropped most "lockdown" measures. It was a calculated risk: one or two million dead in a little over a month, millions more needing hospitalization, and the country survived the blow.
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