Abstract
The Bacillus Calmette–Guérin (BCG) is a well-known vaccine with almost a century of use, with the apparent capability to improve cytokine production and epigenetics changes that could develop a better response to pathogens. It has been postulated that BCG protection against SARS-CoV-2 has a potential role in the pandemic, through the presence of homologous amino acid sequences. To identify a possible link between BCG vaccination coverage and COVID-19 cases, we used official epidemic data and Ecuadorian Ministry of Health and Pan American Health Organization vaccination information. BCG information before 1979 was available only at a national level. Therefore, projections based on the last 20 years were performed, to compare by specific geographic units. We used a Mann–Kendall test to identify BCG coverage variations, and mapping was conducted with a free geographic information system (QGIS). Nine provinces where BCG vaccine coverage was lower than 74.25% show a significant statistical association (χ2 Pearson’s = 4.800, df = 1, p = 0.028), with a higher prevalence of cases for people aged 50 to 64 years than in younger people aged 20 to 49 years. Despite the availability of BCG vaccination data and the mathematical models needed to compare these data with COVID-19 cases, our results show that, in geographic areas where BCG coverage was low, 50% presented a high prevalence of COVID-19 cases that were young; thus, low-coverage years were more affected.
Highlights
SARS-CoV-2 was accidentally discovered in China towards the end of 2019, when a cluster of unidentified viral pneumonia cases occurred in Hubei province
As the vast majority of COVID-19 cases in Ecuador were concentrated in adults and young people (20–50 years old) and focused on certain areas of the country, the objective of this report was to correlate the rate of COVID-19 cases adjusted per 10,000 inhabitants with previous exposure to the Bacillus Calmette–Guérin (BCG) vaccine 40 years ago
It has been proposed that exposure to selected vaccines, such as BCG or microbial components, can increase the baseline tone of innate immunity and trigger pathogenagnostic antimicrobial resistance, a process known as trained innate immunity, which is directly relevant to resistance against infectious diseases, including COVID-19 [26]
Summary
SARS-CoV-2 was accidentally discovered in China towards the end of 2019, when a cluster of unidentified viral pneumonia cases occurred in Hubei province. The virus was discovered to cause an acute respiratory syndrome, named coronavirus disease 2019 (COVID-19), mostly affecting the elderly (i.e., over 60 years of age) and individuals with underlying health conditions [1,2]. From viral transmission mechanisms [5] to COVID-19 treatments [6], researchers are attempting to understand the disease dynamics better and reduce its burden on humankind. The global spread of COVID-19 cases drives research to attempt to understand how environmental factors may contribute to SARS-CoV-2 transmission and COVID-19 disease severity [7,8]
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