Is it possible to flatten-the-curve after the initial outbreak of Covid-19? A data-driven modeling analysis for Omicron pandemic in China

In the current coronavirus disease 2019 (COVID-19) pandemic, the Omicron variant of severe acute respiratory syndrome coronavirus 2 has become the predominant strain circulating worldwide. In China, enormous controversies exist regarding the “dynamic zero tolerance” (DZT) and “totally no inventions” (TNI) strategies for preventing the spread of the Omicron variant. Currently, China is gradually relaxing the COVID-19 measures from DZT level. In such situations, the “flatten-the-curve” (FTC) strategy, which decreases and maintains the low rate of infection to avoid overwhelming the healthcare system by adopting relaxed nonpharmaceutical interventions (NPIs) after the initial outbreak, has been perceived as most appropriate and effective method to prevent the spread of the Omicron variant. Hence, we established a data-driven model of Omicron transmission based on the pandemic data of Macau, Hong Kong, and Singapore in 2022 to deduce the overall prevention effect throughout China. In the current immunity level without any NPI applied, more than 12.7 billion (including asymptomatic individuals) were infected with the Omicron variant within 90 days, but the daily new infections sharply declined; moreover, Omicron outbreak would result to 1.49 million deaths within 180 days. The application of FTC could decrease the deaths by 36.91% within 360 days. Age-stratified analyses showed that the NPI application among individuals aged >60 years would also result in 0.81 million deaths within 360 days, and the application of FTC strategy through treatment with anti-COVID drugs can reduce the number of deaths to 0.40 million. In a model of completed vaccination, the application of TNI strategy would also result in 0.56 million deaths and slightly decrease the infection numbers. The strict implementation of FTC policy combined with completed vaccination and drug use, which only resulted in 0.19 million deaths in an age-stratified model, will help end the pandemic within about 240 days. The pandemic would be terminated within a shorter period of time without resulting in a high fatality rate; therefore, the FTC policy could be strictly implemented through enhancement of immunity and drug use.