Transmissibility quantification of norovirus outbreaks in 2016−2021 in Beijing, China

The transmissibility is a crucial feature for norovirus, yet its quantitative estimation has been limited. Our objective was to estimate the basic reproduction number (R0) of norovirus and investigate its variation characteristics. Norovirus outbreaks reported from September 2016 to August 2021 in Beijing were analyzed. The susceptible‐infected‐removed compartment model was established to estimate R0. Linear regression models and logistic regression models were used to explore the factors affecting the transmissibility of norovirus. The overall median R0 of norovirus was estimated as 2.1 (interquartile range [IQR] 1.8–2.5), with 650 norovirus outbreaks. The transmissibility of norovirus varied by year, outbreak setting and genotype. The R0 of norovirus during September 2019 to August 2020 (median 2.1, IQR 1.8–2.4) and September 2020 to August 2021 (median 2.0, IQR 1.7–2.3) was lower than that of September 2016 to August 2017 (median 2.3, IQR 1.8–2.7) (β = 0.94, p = 0.05; β = 0.93, p = 0.008). The R0 of norovirus for all other settings was lower than that for kindergarten (median 2.4, IQR 2.0–2.9) (primary school: median 2.0, IQR 1.7–2.4, β = 0.94, p = 0.001; secondary school: median 1.7, IQR 1.5–2.0, β = 0.87, p