Seroprevalence of SARS-CoV-2 antibodies in blood donors during the third wave of infection in Campeche Mexico.

At the end of 2020 and previous to the second wave of COVID-19 in Mexico, the seroprevalence in unvaccinated people in the state of Campeche, Mexico was below 15 %. The prevalence changes with ongoing pandemic and per geographical areas. Blood donors screening is a powerful and cost-effective alternative to monitor the population's infection exposure. The aim of the study was to estimate IgG anti-SARS-CoV-2 seropositivity in the Campeche's main blood bank in Mexico. This was a cross-sectional study carried out at the main blood bank of the State of Campeche, located in the Yucatan peninsula, Mexico for the period of August through September 2021 during the third wave of the epidemic. A blood sample from 479 blood donors were included in the study, the overall seropositivity for SARS-CoV-2 IgG antibodies was 69.1 %. Vaccinated donors represented 69.9 % versus 29.4 % unvaccinated. The seropositivity in unvaccinated represented 42.5 % and 81.17 % in vaccinated. The seroconversion in vaccinated donors after first shot was 79 % for Astra-Zeneca-vaccine and 90 % for Pfizer-vaccine. In conclusion 69.1 % of blood donors are seropositive for SARS-CoV-2 and 42.5 percent unvaccinated people are already also seropositive.

Leukoreduction by centrifugation does not eliminate Trypanosoma cruzi from infected blood units.

Current strategies to prevent transfusion-associated Chagas disease include the identification of Trypanosoma cruzi-infected blood donors through questionnaires and serologic tests. There are other procedures such as leukoreduction that prevent the transmission of infectious agents associated to white cells. The objective of the present work was to estimate the seroprevalence, evaluate the efficacy of leukoreduction by centrifugation to eliminate T. cruzi in infected blood units, and the correlation of immunoglobulin G (IgG) subclasses of seropositive blood donors with chronic chagasic cardiopathy. Over a period of 14 months, 33 out of 6600 blood donors (0.5%) at Centro Estatal de la Transfusión Sanguínea in Campeche State, México were seropositive for T. cruzi. Twenty seropositive blood units were submitted through leukoreduction by centrifugation, and in the fractions generated (red cell fraction, platelets, and the buffy-coat), we searched for the presence of T. cruzi using specific polymerase chain reaction. We detected parasite DNA in 50% to 60% of the fractions tested, suggesting that leukoreduction by centrifugation does not eliminate the microorganisms in the infected blood unit. We also observed that the level of IgG2 and IgG4 subclasses specific for T. cruzi in seropositive blood donors was lower than in chronic cardiopathic chagasic patients. In conclusion, leukoreduction by centrifugation has a limited role in eliminating T. cruzi in infected blood supply, and the low level of specific IgG2 and IgG4 could be a marker in the indeterminate phase of infection.