Coronavirus disease 2019 scenarios for a long-term strategy under fundamental uncertainty.

Early on, scientists have pointed out that coronavirus disease 2019 is most likely here to stay, although its course and development are uncertain. This requires a long-term strategy of living with the virus. However, the urgency of new waves of infection and the emergence of new variants have invoked an approach of acute crisis management over and over, hindering the design of a structural approach for the long term. Exploratory scenarios can provide scientific strategic guidance to policy processes to be better prepared in this situation of fundamental uncertainty. We have therefore developed five scenarios, which describe the possible long-term development of the pandemic from an epidemiological, virological, and broader societal perspective. These scenarios are based on four driving forces that are both important and uncertain: immunity, vaccination, mutations, and human behavior. The scenarios are (1) return to normal, (2) flu+, (3) external threat, (4) continuous struggle, and (5) worst case. Working with scenarios is crucial for appropriate public communication and provides guidance for anticipating the various conceivable possibilities for the further course of the pandemic.

Impact of influenza vaccination on GP-diagnosed COVID-19 and all-cause mortality: a Dutch cohort study.

OBJECTIVES: As clinical presentation and complications of both viruses overlap, it was hypothesised that influenza vaccination was associated with lower general practitioner (GP)-diagnosed COVID-19 rates and lower all-cause mortality rates. STUDY DESIGN: From a primary care population-based cohort in the Netherlands, GP-diagnosed COVID-19 (between 10 March and 22 November 2020) and all-cause mortality events (between 30 December 2019 and 22 November 2020) were recorded. 223 580 persons were included, representing the influenza vaccination 2019 target group (all aged ≥60 years, and those <60 years with a medical indication). Proportional hazards regression analyses evaluated associations between influenza vaccination in 2019 and two outcomes: GP-diagnosed COVID-19 and all-cause mortality. Covariables were sex, age, comorbidities and number of acute respiratory infection primary care consultations in 2019. RESULTS: A slightly positive association (HR 1.15; 95% CI 1.08 to 1.22) was found between influenza vaccination in 2019 and GP-diagnosed COVID-19, after adjusting for covariables. A slightly protective effect for all-cause mortality rates (HR 0.90; 95% CI 0.83 to 0.97) was found for influenza vaccination, after adjusting for covariables. A subgroup analysis among GP-diagnosed COVID-19 cases showed no significant association between influenza vaccination in 2019 and all-cause mortality. CONCLUSIONS: Our hypothesis of a possibly negative association between influenza vaccination in 2019 and GP-diagnosed COVID-19 was not confirmed as we found a slightly positive association. A slightly protective effect on all-cause mortality was found after influenza vaccination, possibly by a wider, overall protective effect on health. Future research designs should include test-confirmed COVID-19 cases and controls, adjustments for behavioural, socioeconomic and ethnic factors and validated cause-specific mortality cases.