Effect of BCG Revaccination on Occupationally Exposed Medical Personnel Vaccinated against SARS-CoV-2.

Dennisse S. Galicia-Álvarez,Isaac Bárcenas-Montiel,Guillermo Velázquez-Sámano,Andrea Velasco-Medina,Espiridión Ramos-Martinez,Jorge Rojas-Serrano,Ramcés Falfán-Valencia,Gloria Pérez-Rubio,Warrison Athanasio Andrade,Enrique Ambrocio-Ortiz

doi:10.3390/cells10113179

Abstract

The production of specific neutralizing antibodies by individuals is thought to be the best option for reducing the number of patients with severe COVID-19, which is the reason why multiple vaccines are currently being administered worldwide. We aimed to explore the effect of revaccination with BCG, on the response to a subsequent anti-SARS-CoV-2 vaccine, in persons occupationally exposed to COVID-19 patients. Two groups of 30 randomized participants were selected: one group received a BCG revaccination, and the other group received a placebo. Subsequently, both groups were vaccinated against SARS-CoV-2. After each round of vaccination, the serum concentration of Th1/Th2 cytokines was determined. At the end of the protocol, neutralizing antibodies were determined and the HLA-DRB loci were genotyped. The participants from the BCG group and anti-SARS-CoV-2 vaccine group had increased serum cytokine concentrations (i.e., IL-1β, IL-4, IL-6, IL-12p70, IL-13, IL-18, GM-CSF, INF-γ, and TNF-α) and higher neutralizing antibody titers, compared to the group with Placebo–anti-SARS-CoV-2. Twelve HLA-DRB1 alleles were identified in the Placebo–anti-SARS-CoV-2 group, and only nine in the group revaccinated with BCG. The DRB1*04 allele exhibited increased frequency in the Placebo–anti-SARS-CoV-2 group; however, no confounding effects were found with this allele. We conclude that revaccination with BCG synergizes with subsequent vaccination against SARS-CoV-2 in occupationally exposed personnel.

Highlights

All participants were negative on the Mantoux test and did not present suggestive features of pulmonary disease due to tuberculosis based in the chest radiography
The Bacillus Calmette–Guérin (BCG) vaccine is universally applicable in Mexico; all participants had a history of previous immunization in childhood, verified through the national vaccination records
At the end of stage 3, our result showed that the participants in the group with the combination of BCG and anti-severe acute respiratory syndrome (SARS)-CoV-2 vaccines had significantly higher neutralization percentages (89.57% [63.43–98.27%]), than the group of participants with the placebo–COVID-19 combination (63.49% [13.45–80.42%]) (Figure 3)

Summary

Introduction

The first barrier that viruses must overcome to infect a new host is entry into the host cell, a phenomenon in which two variables intervene: the first is efficient virus binding to the host cell—in the case of SARS-CoV-2, this is due to its high affinity for the ACE2 receptor; and the second is the host-mediated inhibition of this process, through mechanisms such as neutralization by specific antibodies [9] The production of these types of antibodies has been suggested to be the most efficient way to reduce the impact of this virus on the global population. Preventative vaccination is the safest and most cost-effective way to prevent

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