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COVID-19: Lifting China’s zero-COVID strategy could trigger Omicron wave

China could see an Omicron wave resulting in approximately 1.55 million deaths and a projected intensive care unit (ICU) peak demand of up to 15.6 times the existing capacity, should its current dynamic zero-COVID strategy be lifted. The findings are published as part of a modeling study in Nature Medicine.

China’s dynamic zero-COVID strategy — which aims at cutting off transmission chains and quickly ending outbreaks — has been in place since August 2021 to respond to SARS-CoV-2 variants with higher levels of transmissibility (such as Delta and Omicron). However, China is now evaluating the sustainability of this policy and potential mitigation strategies.

As of 18 April 2022, 91.4% of the population in China over 3 years of age had received the full schedule of COVID-19 vaccination, and 53.7% of them had received a booster shot. However, this immunity may not be enough to prevent outbreaks. From 1 March to 22 April 2022, more than 500,000 Omicron infections had been reported in almost all provinces across China, with 93% occurring in Shanghai. To explore the possibility of shifting from pandemic containment to mitigation while minimizing disease burden (which includes the number of patients requiring hospitalization and intensive care, and deaths), Hongjie Yu and colleagues developed a mathematical model of SARS-CoV-2 transmission adjusted for the initial growth phase for the 2022 Omicron outbreak in Shanghai to project COVID-19 burden should the dynamic zero-COVID policy be lifted.

In the baseline scenario, which considered a population vaccinated with the booster and an absence of enhanced non-pharmaceutical interventions (NPIs) such as mass testing and mobility restrictions, and antiviral therapies, the emergence of the Omicron variant in March 2022 may have the potential to cause as many as 5.1 million hospital admissions, 2.7 million ICU admissions and 1.55 million deaths within a 6-month period up to September 2022. Unvaccinated people 60 years of age and older are projected to account for 74.7% of the total number of deaths due to the gap in vaccination coverage.

The authors also investigated the impact of three types of strategies to mitigate the COVID-19 burden: promoting further vaccination, including booster doses and promoting vaccination among unvaccinated people 60 years of age and older; antiviral therapies; and enhanced NPIs. None of the assessed individual mitigation strategies alone is enough to reduce the death toll to the level of an influenza season or to prevent exceeding the demand for critical care. However, the authors found that a combination of strategies — including further vaccination of elderly and vulnerable people, providing access to antiviral medication, and NPIs — could reduce the death toll and prevent overwhelming of the healthcare system.