Projecting the transmission dynamics of SARS-CoV-2 through the post-pandemic period

Stephen M Kissler; Christine Tedijanto; Edward Goldstein; Yonatan H. Grad; Marc Lipsitch

Our study was subject to a variety of limitations. Only five seasons of observational data on coronaviruses were available, though the incidence patterns resemble those from 10 years of data from a hospital in Sweden (10) . We assumed that the spline coefficients were constant across all seasons though seasonal forcing likely differed from year to year based on underlying drivers. To keep the transmission model from becoming unreasonably complex, we assumed that there was no difference in the seasonal forcing, per-case force of infection, incubation period, or infectious period across betacoronaviruses. However, our estimates for these values lie within the ranges of estimates from the literature, so we do not anticipate that this detracted from our results. We also did not directly model any effect from the opening of schools, which could lead to an additional boost in transmission strength in the early autumn (27) , or any effects of behavior change or control efforts, which could suppress the effective reproduction number. The transmission model is deterministic, so it cannot capture the possibility of SARS-CoV-2 extinction.