Vaccination against COVID-19 and society return to normality in England: a modelling study of impacts of different types of naturally acquired and vaccine induced immunity

Song, F.; Bachmann, M. O.

Objectives: To project impacts of mass vaccination against COVID-19, and investigate possible impacts of different types of naturally acquired and vaccine-induced immunity on future dynamics of SARS-CoV-2 transmission from 2021 to 2029 in England. Design: deterministic, discrete-time population dynamic modelling. Participants: Population in England. Interventions: mass vaccination programmes. Outcome measures: daily and cumulative number of deaths from COVID-19. Results: If vaccine efficacy is [≥]70%, the vaccine-induced sterilising immunity lasts [≥]182 days, and the reinfectivity is greatly reduced (by [≥]40%), annual mass vaccination programmes can prevent further COVID-19 outbreaks in England. Under such optimistic scenarios, the cumulative number of COVID-19 deaths is estimated to be from 113,000 to 115,000 by the end of 2029 in England. However, under plausible scenarios with lower vaccine efficacy, shorter durability of immunity, and smaller reduction in reinfectivity, repeated vaccination programmes could not prevent further COVID-19 outbreaks. Conclusions: Under optimistic scenarios, mass immunisation using efficacious vaccines may enable society safely to return to normality. Because of great uncertainty in the impacts of mass vaccination on COVID-19 pandemics, it is crucial to monitor vaccination effects in the real world, and to better understand characteristics of naturally acquired and vaccine induced immunity against SARS-CoV-2.