Cohort profile: evaluation of immune response and household transmission of SARS-CoV-2 in Costa Rica: the RESPIRA study.

PURPOSE: The RESPIRA cohort aims to describe the nature, magnitude, time course and efficacy of the immune response to SARS-CoV-2 infection and vaccination, population prevalence, and household transmission of COVID-19. PARTICIPANTS: From November 2020, we selected age-stratified random samples of COVID-19 cases from Costa Rica confirmed by PCR. For each case, two population-based controls, matched on age, sex and census tract were recruited, supplemented with hospitalised cases and household contacts. Participants were interviewed and blood and saliva collected for antibodies and PCR tests. Participants will be followed for 2 years to assess antibody response and infection incidence. FINDINGS TO DATE: Recruitment included 3860 individuals: 1150 COVID-19 cases, 1999 population controls and 719 household contacts from 304 index cases. The age and regional distribution of cases was as planned, including four age strata, 30% rural and 70% urban. The control cohort had similar sex, age and regional distribution as the cases according to the study design. Among the 1999 controls recruited, 6.8% reported at enrolment having had COVID-19 and an additional 12.5% had antibodies against SARS-CoV-2. Compliance with visits and specimens has been close to 70% during the first 18 months of follow-up. During the study, national vaccination was implemented and nearly 90% of our cohort participants were vaccinated during follow-up. FUTURE PLANS: RESPIRA will enable multiple analyses, including population prevalence of infection, clinical, behavioural, immunological and genetic risk factors for SARS-CoV-2 acquisition and severity, and determinants of household transmission. We are conducting retrospective and prospective assessment of antibody levels, their determinants and their protective efficacy after infection and vaccination, the impact of long-COVID and a series of ancillary studies. Follow-up continues with bimonthly saliva collection for PCR testing and biannual blood collection for immune response analyses. Follow-up will be completed in early 2024. TRIAL REGISTRATION NUMBER: NCT04537338.

Social gradient in cancer incidence in Costa Rica: Findings from a national population-based cancer registry.

BACKGROUND: The main evidence regarding social inequalities in cancer risk comes from industrialized countries. The aim of this manuscript was to analyze the association between cancer incidence and socioeconomic position (SEP) in a middle-income country (Costa Rica) between 2011 and 2015. METHODS: An ecological study at the level of the electoral district was conducted. The 477 districts were divided by area and wealth using the 2011 Census. The sample was defined using the National Electoral Rolls used for presidential elections of 2006 and 2010 (N = 2 798 517). 44 799 cancer cases were included coming from the Costa Rican Cancer Registry. Cox models were used. RESULTS: All cancer sites combined, we observed a positive gradient, with incidence being lower in the poorest districts than in the wealthiest (HRQ2 = 0.98 [0.93-1.03], HRQ3 = 0.92 [0.85-0.99], HRQ4 = 0.83 [0.77-0.88]). For colon, skin, breast, prostate, thyroid and other cancer sites, a positive social gradient was observed. For stomach, lung, and cervical (invasive or in-situ) cancers, a negative social gradient was found. For uterine cancer and lymphoma (no-Hodgkin), there was no significant relationship between wealth and incidence. For skin cancer, incidence was higher in rural as compared to urban areas after adjustment for wealth. For lung, cervical and uterine cancer, incidence was lower in rural as compared to urban area after adjustment for wealth. CONCLUSIONS: The all-cancer combined results were in contradiction with the international literature but confirmed recent study results in Costa Rica. It confirmed the importance of studying socioeconomic inequalities in middle-income countries.