Excess mortality from COVID 19 in Costa Rica: a registry based study using Poisson regression.

Background: Official death toll related to COVID-19 has been considerably underestimated in reports from some Latin American countries. This study aimed to analyze the mortality associated with the COVID-19 pandemic in Costa Rica between March 2020 and December 2021. Methods: A registry based study based on 2017-2021 data from the National Institute of Statistics and Census was designed (N = 128,106). Excess deaths were defined by the WHO as "the difference in the total number of deaths in a crisis compared to those expected under normal conditions"; and were estimated using a Poisson regression, and mortality and years of potential life lost (YPLL) rates were calculated. Findings: The COVID-19 pandemic represented 15% of the deaths in Costa Rica between March 2020 and December 2021. The mortality rate related to COVID-19 was 83 per 100,000 person-years. Between March and July 2020 (low-incidence period), observed number of deaths was 9%-lower than expected, whereas it was 15% and 24% higher than expected between July 2020 and March 2021 (high incidence period - no vaccination), and between March 2021 and December 2021 (high incidence period - progressive vaccination) respectively. Between July 2020 and December 2021, excess deaths observed and COVID-19 deaths reported were comparable (7461 and 7620 respectively). Nevertheless, there were more deaths than expected for conditions that predispose to COVID-19 deaths. YPLL and mortality rates increased with age, but significant excess deaths were observed in all age-groups older than 30-39 years. No large differences were noted by districts' socioeconomic characteristics although excess death rate was lower in rural compared to urban areas. Interpretation: Reporting of deaths was only slightly underestimated. In the pre-vaccination period, mortality rate and YPLL rates increased with age, being highest in people aged 60 years or older and justifying the decision to initially prioritize vaccination of older individuals. Funding: The study was supported by the University of Costa Rica and the Agencia Costarricense de Investigaciones Biomédicas - Fundación Inciensa.

Estimating vaccine effectiveness against SARS-CoV-2 infection, hospitalization and death from ecologic data in Costa Rica.

BACKGROUND: Clinical trials and individual-level observational data in Israel demonstrated approximately 95% effectiveness of mRNA-based vaccines against symptomatic SARS-CoV-2 infection. Individual-level data are not available in many countries, particularly low- and middle- income countries. Using a novel Poisson regression model, we analyzed ecologic data in Costa Rica to estimate vaccine effectiveness and assess the usefulness of this approach. METHODS: We used national data from December 1, 2020 to May 13, 2021 to ascertain incidence, hospitalizations and deaths within ecologic units defined by 14 age groups, gender, 105 geographic areas, and day of the epidemic. Within each unit we used the proportions of the population with one and with two vaccinations, primarily tozinameran. Using a non-standard Poisson regression model that included an ecologic-unit-specific rate factor to describe rates without vaccination and a factor that depended on vaccine effectiveness parameters and proportions vaccinated, we estimated vaccine effectiveness. RESULTS: In 3.621 million persons aged 20 or older, there were 125,031 incident cases, 7716 hospitalizations, and 1929 deaths following SARS-CoV-2 diagnosis; 73% of those aged ≥ 75 years received two doses. For one dose, estimated effectiveness was 59% (95% confidence interval 53% to 64%) for SARS-CoV-2 incidence, 76% (68% to 85%) for hospitalizations, and 63% (47% to 80%) for deaths. For two doses, the respective estimates of effectiveness were 93% (90% to 96%), 100% (97% to 100%), and 100% (97% to 100%). CONCLUSIONS: These effectiveness estimates agree well with findings from clinical trials and individual-level observational studies and indicate high effectiveness in the general population of Costa Rica. This novel statistical approach is promising for countries where ecologic, but not individual-level, data are available. The method could also be adapted to monitor vaccine effectiveness over calendar time.

[COVID-19 deaths: Distribution by age and universal medical coverage in 22 countriesMortes por COVID-19: distribuição por idade e universalidade da cobertura médica em 22 países]. / Defunciones por COVID-19: distribución por edad y universalidad de la cobertura médica en 22 países.

OBJECTIVE: Relate standardized age distribution of COVID-19 deaths in 22 countries in the Americas and Europe to different indicators of population characteristics and health systems. METHODS: Distributions of COVID-19 deaths by age group in 22 countries of the Americas and Europe were standardized based on the age pyramid of the world's population. Correlations were calculated between the standardized proportion of people aged <60 years among the deceased and each of six indicators. RESULTS: Standardization based on the world age pyramid revealed considerable differences in age distribution among countries; the proportion of people aged <60 years was higher in Latin America and the United States than in Canada or Western Europe. The standardized proportion of people aged <60 years among persons who died of COVID-19 is strongly correlated to the existence of universal quality medical coverage (r=-0.92, p<0.01). This relationship remained significant after being adjusted for the other indicators. CONCLUSION: We propose that weaknesses in medical coverage of the population may have created higher case-fatality in populations aged <60 years in Latin America and the United States.

OBJETIVO: Correlacionar a distribuição etária padronizada de mortes por COVID-19 em 22 países das Américas e da Europa com diversos indicadores das características das populações e dos sistemas de saúde. MÉTODOS: As distribuições das mortes por COVID-19 por faixa etária em 22 países das Américas e da Europa foram padronizadas pela pirâmide etária da população mundial. Foram calculadas correlações entre a proporção padronizada de pessoas com menos de 60 anos entre as pessoas que morreram e cada um dos seis indicadores. RESULTADOS: Foram evidenciadas diferenças importantes de distribuição etária entre os países estudados após a padronização pela pirâmide etária da população mundial, sendo maior a proporção de mortes de pessoas com menos de 60 anos na América Latina e nos Estados Unidos que no Canadá ou na Europa ocidental. A proporção padronizada de pessoas com menos de 60 anos entre as pessoas que morreram por COVID-19 está fortemente correlacionada com a universalidade de cobertura médica de qualidade (r=­0,92, p<0,01). Esta correlação se manteve significativa após o ajuste para outros indicadores analisados. CONCLUSÃO: O nosso estudo sugere que falhas na cobertura médica da população podem ter provocado maior letalidade nas pessoas com menos de 60 anos na América Latina e nos Estados Unidos.