ABSTRACT
Booster doses of the SARS-CoV-2 vaccine have been recommended to improve and prolong immunity, address waning immunity over time, and contribute to the control of the COVID-19 pandemic. A heterologous booster vaccine strategy may offer advantages over a homologous approach. To compare the immunogenicity of two doses of BNT162b2 mRNA COVID-19 vaccine with a ChAdOx1-S booster dose, immunoglobulin G (IgG) anti-spike (anti-S) and anti-nucleocapsid (anti-N) antibody titers (Ab) were compared over 1 year and post-booster vaccination. Results showed that, at 3- to 9-month assessments in vaccinated subjects, an-ti-N Ab were undetectable in participants with no history of COVID-19. In contrast, anti-S Ab measurements were lower than those with COVID-19, and a decrease was observed during the 9 months of observation. After booster vaccination, no differences were found in anti-S between participants who reported a history of COVID-19 and those who did not. Anti-S levels were higher after booster vaccination measurement vs. at 9 months in participants with COVID-19 and without COVID-19, i.e., independent of an infection history. Vaccine administration elicited a response of higher anti-S IgG levels in those infected before vaccination, although levels decreased during the first nine months. IgG anti-N titers were higher in participants with a history of declared infection and who were asymptomatic. The ChAdOx1-S booster increased anti-S Ab levels in participants regardless of whether they had been infected or not to a significantly higher value than with the first two vaccines. These findings underscore the importance of booster vaccination in eliciting a robust and sustained immune response against COVID-19, regardless of the prior infection status.
Subject(s)
Antibodies, Viral , BNT162 Vaccine , COVID-19 Vaccines , COVID-19 , Immunization, Secondary , Immunogenicity, Vaccine , Immunoglobulin G , Military Personnel , SARS-CoV-2 , Humans , BNT162 Vaccine/immunology , BNT162 Vaccine/administration & dosage , COVID-19/prevention & control , COVID-19/immunology , Antibodies, Viral/blood , Antibodies, Viral/immunology , Male , SARS-CoV-2/immunology , COVID-19 Vaccines/immunology , COVID-19 Vaccines/administration & dosage , Adult , Mexico , Female , Immunoglobulin G/blood , Immunoglobulin G/immunology , Spike Glycoprotein, Coronavirus/immunology , ChAdOx1 nCoV-19/immunology , ChAdOx1 nCoV-19/administration & dosage , Young Adult , Vaccination , Middle AgedABSTRACT
Background: The use of convalescent plasma (CP) has been considered for its immunological mechanisms that could benefit patients in moderate and severe stages of COVID-19. This study evaluated the safety and efficacy of the use of donor CP for COVID-19. Material and methods: A double-blind, randomized controlled clinical trial was conducted from May to October 2020. Thirty-nine participants with moderate (II) and severe (III) stages of COVID-19 confirmed by RT-PCR were included. The study randomization rate was set at 3:1. CPs were chosen for application with a neutralizing antibody titer of ≥1:32. Results: We observed a significantly lower 21-day post-transfusion mortality HR: 0.17 (95.0% CI [0.07−0.45, p < 0.001]) in the group receiving CP compared with the control group; protective units (PU) in the group receiving convalescent plasma after seven days were significantly higher (512 (32−16,384) vs. 96 (32−256), p = 0.01); the PAO2/FIO2 index showed a significant improvement in the group receiving CP (251.01 (109.4) vs. 109.2 (62.4), p < 0.001, in the control group). Conclusion: CP is safe and effective, as it decreased mortality in the CP group compared with the control group.
