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BackgroundThis work analyses the impact of different vaccination strategies on the propagation of COVID-19 within the Madrid metropolitan area starting the 27th of December 2020 and ending in the Summer of 2021. The predictions are based on simulation using EpiGraph, an agent-based COVID-19 simulator. MethodsWe briefly summarize the different interconnected models of EpiGraph and then we provide a comprehensive description of the vaccination model. We evaluate different vaccination strategies, and we validate the simulator by comparing the simulation results with real data from the metropolitan area of Madrid during the third wave. ResultsWe consider the different COVID-19 propagation scenarios on a social environment consisting of the ten largest cities in the Madrid metropolitan area, with 5 million individuals. The results show that the strategy that fares best is to vaccinate the elderly first with the two doses spaced 56 days apart; this approach reduces the final infection rate and the number of deaths by an additional 6% and 3% with respect to vaccinating the elderly first at the interval between doses recommended by the vaccine producer. ConclusionResults show that prioritizing the vaccination of young individuals would significantly increase the number of deaths. On the other hand, spacing out the first and second dose by 56 days would result in a slight reduction in the number of infections and deaths. The reason is the increase in the number of vaccinated individuals at any time during the simulation.
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ObjectiveTo estimate the range of the age- and sex-specific infection fatality risk (IFR) for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) based on confirmed coronavirus disease 2019 (COVID-19) deaths and excess all-cause deaths. DesignNationwide population-based seroepidemiological study combined with two national surveillance systems. Setting and participantsNon-institutionalized Spanish population of all ages. Main outcome measuresThe range of IFR was calculated as the observed number of COVID-19 deaths and excess deaths divided by the estimated number of SARS-CoV-2 infections in the non-institutionalized Spanish population. Laboratory-confirmed COVID-19 deaths were obtained from the National Epidemiological Surveillance Network (RENAVE) and excess all-cause deaths from the Monitoring Mortality System (MoMo) up to July 15, 2020. SARS-CoV-2 infections were derived from the estimated seroprevalence by a chemiluminiscent microparticle immunoassay for IgG antibodies in 61,092 participants in the ENE-COVID nationwide serosurvey between April 27 and June 22, 2020. ResultsThe overall IFR (95% confidence interval) was 0.8% (0.8% to 0.9%) for confirmed COVID-19 deaths and 1.1% (1.0% to 1.2%) for excess deaths. The IFR ranged between 1.1% (1.0% to 1.2%) and 1.4% (1.3% to 1.5%) in men and between 0.6% (0.5% to 0.6%) and 0.8% (0.7% to 0.8%) in women. The IFR increased sharply after age 50, ranging between 11.6% (8.1% to 16.5%) and 16.4% (11.4% to 23.2%) in men [≥]80 years and between 4.6% (3.4% to 6.3%) and 6.5% (4.7% to 8.8%) in women [≥]80 years. ConclusionThe sharp increase in SARS-CoV-2 IFR after age 50 was more marked in men than in women. Fatality from COVID-19 is substantially greater than that reported for other common respiratory diseases such as seasonal influenza. WHAT IS ALREADY KNOWN ON THIS TOPICInfection fatality risk (IFR) for SARS-CoV-2 is a key indicator for policy decision making, but its magnitude remains under debate. Case fatality risk, which accounts for deaths among confirmed COVID-19 cases, overestimates SARS-CoV-2 fatality as it excludes a large proportion of asymptomatic and mild-symptomatic infections. Population-based seroepidemiological studies are a valuable tool to properly estimate the number of infected individuals, regardless of symptoms. Also, because ascertainment of deaths due to COVID-19 is often incomplete, the calculation of the IFR should be complemented with data on excess all-cause mortality. In addition, data on age- and sex-specific IFR are scarce, even though age and sex are well known modifiers of the clinical evolution of COVID-19. WHAT THIS STUDY ADDSUsing the ENE-COVID nationwide serosurvey and two national surveillance systems in Spain, this study provides a range of age- and sex-specific IFR estimates for SARS-CoV-2 based on laboratory-confirmed COVID-19 deaths and excess all-cause deaths. The risk of death was very low among infected individuals younger than 50 years, but it increased sharply with age, particularly among men. In the oldest age group ([≥]80 years), it was estimated that 12% to 16% of infected men and 5% to 6% of infected women died during the first epidemic wave.
