Citizen science initiative points at childhood BCG vaccination as a risk factor for COVID‐19
José de la Fuente, Octavio Armas, Luis Sánchez Rodríguez, Christian Gortázar, Alexander N. Lukashev, COVID‐BCG Collaborative Working Group, Consuelo Almazán, Isabel G. Fernández de Mera, Margarita Villar, Marinela Contreras, Elisa Ferreras‐Colino, Jānis Ancāns, Alejandro Cabezas‐Cruz, José Miguel Urra, Carmen Cabrera, Francisco J. Rodríguez del Río, Lorena Torres, Andrei Daniel Mihalca, Fredrick Kabi, Dibesh Karmacharya, Espiridión Ramos-Martı́nez, Vidal Montoro, Katherine M. Kocan, Edmour F. Blouin, Hugo Fragoso, Sergio E. Bermúdez, Agustín Estrada‐Peña, Luis M. Hernández‐Triana, Michail Kotsyfakis, Libor Grubhoffer, Gabriela de la Fuente, Karelia Deulofeu, Leticia Deulofeu, Anna Zelinska‐Fedorovych, Zorica Živković, Ana Domingos, Anna Papa, Ard M. Nijhof, Mónica Florin‐Christensen, Lucas Domı́nguez, Mercedes Domínguez, Juan Luis Mosqueda-Gómez, Octávio Merino, Ala E. Tabor, Albert Mulenga, Ernesto Doncel‐Pérez, Gervacio H. Bechara, Srikant Ghosh, Alessandra Torina, Guido Sireci, Rodrigo Salvo Nova, João Queirós
Abstract
Current results do not provide conclusive evidence on the effect of BCG vaccination on COVID-19 alone or in combination with other factors. To address this limitation, in this study we used a citizen science initiative on the COVID-19 pandemic to collect data worldwide during 2 October 2020-30 October 2020 (1,233 individuals) in a structured way for analysing factors and characteristics of affected individuals in relation to BCG vaccination. For the first time, the results of our study suggested that vaccination with BCG may increase the risk for COVID-19 at certain age, particularly in individuals vaccinated at childhood. Childhood BCG vaccination increased the likelihood of being diagnosed with COVID-19 fivefold in COVID-19 low-incidence countries and threefold in high-incidence countries. A reasonable explanation for this effect is the activation of certain innate immunity mechanisms associated with inflammatory reactions. These factors should be considered when analysing the risks associated with this global pandemic.