The impact of multi-level interventions on the second-wave SARS-CoV-2 transmission in China

Abstract

Background A re-emergence of COVID-19 occurred in the northeast of China in early 2021. Different levels of non-pharmaceutical interventions, from mass testing to city-level lockdown, were implemented to contain the transmission of SARS-CoV-2. Our study is aimed to evaluate the impact of multi-level control measures on the second-wave SARS-CoV-2 transmission in the most affected cities in China. Methods Five cities with over 100 reported COVID-19 cases within one month from Dec 2020 to Feb 2021 were included in our analysis. We fitted the exponential growth model to estimate basic reproduction number (R-0), and used a Bayesian approach to assess the dynamics of the time-varying reproduction number (R-t). We fitted linear regression lines on R-t estimates for comparing the decline rates of R-t across cities, and the slopes were tested by analysis of covariance. The effect of non-pharmaceutical interventions (NPIs) was quantified by relative R-t reduction and statistically compared by analysis of variance. Results A total of 2,609 COVID-19 cases were analyzed in this study. We estimated that R-0 all exceeded 1, with the highest value of 3.63 (1.36, 8.53) in Haerbin and the lowest value of 2.45 (1.44, 3.98) in Shijiazhuang. Downward trends of R-t were found in all cities, and the starting time of R-t < 1 was around the 12th day of the first local COVID-19 cases. Statistical tests on regression slopes of R-t and effect of NPIs both showed no significant difference across five cities (P = 0.126 and 0.157). Conclusion Timely implemented NPIs could control the transmission of SARS-CoV-2 with low-intensity measures for places where population immunity has not been established.