Prevalence of asymptomatic cases of COVID-19 in blood donors from Buenos Aires city

Abstract

Introduction: SARS-COV-2 infection can either be asymptomatic or cause severe acute respiratory síndrome with pneumonia and death. At the beginning of the pandemic, the movement of people and activities in closed spaces were prohibited to avoid contagion and the requirements to donate blood added deferral criteria for those who had suffered from COVID-19. Objectives: To know the prevalence of asymptomaticinfections by SARS-COV-2 during the preventive and mandatory social isolation (ASPO from the term in Spanish) in blood donors and to analyze the distribution by age groups and according to residence of the cases and to describe the relationship with the ABO group. Materials and methods: The anti-protein S IgG level was tested in serum samples from blood donors chosen at random among the donations made during the ASPO. Data on sex, age, address and ABO of each blod donor were obtained from the computerized management system of the blood donation service. Results: A total of 343 donors (46.6 % men) with a mean age of 34.43 years were studied. Twenty-nine asymptomatic cases were found. The prevalence in people under 30 years of age (12.93%) was higher than that for those older than that age (p=0.030) and the IgG titers in the asymptomatic group were significantly higher (p<0.0001) than those in the non-reactive group. Conclusions: The first cases occurred in donors from Buenos Aires, but the speed of spread was greater outside this city. Within Buenos Aires, the prevalences were higher in neighborhoods of lower socioeconomic level. The frequency of group A was lower in the reagents for anti-SARS-COV-2 IgG than in the rest.