Dengue and COVID-19 Co-infection attenuates disease severity: evidence from serological and clinical analyses in a mexican cohort

The SARS-CoV-2 pandemic constituted an unprecedented challenge, in which understanding host-virus dynamics, particularly the pre-existing immunological context in affected populations, was found to be a predictive element of disease progression. In this context, evidence suggests that exposure to viruses influences the immune response to new antigens. In this study, we examined the impact of exposure to mosquito-borne viruses (MBVs) on the progression of COVID-19. We retrospectively analyzed the clinical records of 9,167 patients, 9013 of whom were positive for SARS-CoV-2 Wuhan strain infection, 118 of whom were positive for MBV, and 37 of whom were coinfected (SARS-CoV-2 Wuhan strain/MBV)exposed to arbovirus. Multivariate analysis revealed that the outcome of COVID-19 was affected by exposure to MBV. Our results showed a reduction in the negative effect of the number of symptoms and comorbidities on the development of critical COVID-19. These findings coincided with those obtained from the analysis of sera from 80 patients, including those with Wuhan strain COVID-19 and mild or severe disease, and were grouped according to their previous exposure to DENV. A greater proportion of patients positive for anti-RBD antibodies was identified in the group of mild COVID-19 patients with a previous DENV infection (31%) than in the group of patients non-infected with SARS-CoV-2 DENV and with mild COVID-19, who, in our study, were negative for anti-RBD antibody detection. Collectively, our results suggest that contact with mosquito-transmitted viruses reduces the threshold of the immune response, favoring a more favorable outcome during SARS-CoV-2 infection. Specifically, for DENV, our results indicate that previous infections with this virus promote a more efficient production of antibodies against SARS-CoV-2. Therefore, understanding the impact of frequently circulating etiologies in specific areas benefits the design of emerging virus control guidelines.