Global perspective of COVID‐19 epidemiology for a full‐cycle pandemic

Ioannidis, John P. A.

As of October 2020, there are >1 million documented deaths with COVID‐19. Excess deaths can be caused by both COVID‐19 and the measures taken. COVID‐19 shows extremely strong risk stratification across age, socioeconomic factors, and clinical factors. Calculation of years‐of‐life‐lost from COVID‐19 is methodologically challenging and can yield misleading over‐estimates. Many early deaths may have been due to suboptimal management, malfunctional health systems, hydroxychloroquine, sending COVID‐19 patients to nursing homes, and nosocomial infections; such deaths are partially avoidable moving forward. About 10% of the global population may be infected by October 2020. Global infection fatality rate is 0.15‐0.20% (0.03‐0.04% in those <70 years), with large variability across locations with different age‐structure, institutionalization rates, socioeconomic inequalities, population‐level clinical risk profile, public health measures, and health care. There is debate on whether at least 60% of the global population must be infected for herd immunity, or, conversely, mixing heterogeneity and pre‐existing cross‐immunity may allow substantially lower thresholds. Simulations are presented with a total of 1.58‐8.76 million COVID‐19 deaths over 5‐years (1/2020‐12/2024) globally (0.5‐2.9% of total global deaths). The most favorable figures in that range would be feasible if high risk groups can be preferentially protected with lower infection rates than the remaining population. Death toll may also be further affected by potential availability of effective vaccines and treatments, optimal management and measures taken, COVID‐19 interplay with influenza and other health problems, reinfection potential, and any chronic COVID‐19 consequences. Targeted, precise management of the pandemic and avoiding past mistakes would help minimize mortality.