Neutralizing activity to SARS-CoV-2 in 1.2 to 10.0 month convalescent plasma samples of COVID-19: A transversal surrogate in vitro study performed in Quito-Ecuador.

Coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, was first reported in Wuhan, China, in December 2019. Diagnostic methods for the detection of the virus and seroconversion of neutralizing antibodies (NAbs) in plasma have been developed specifically, but some of them require a BSL3 facility. In this study, we used the SARS-CoV-2 Surrogate Virus Neutralization Test Kit to determine the presence or absence of NAbs anti-receptor binding domain of the viral spike (S) glycoprotein in a BSL2 facility. The sample population was chosen in Quito, Ecuador, with a total of 88 COVID-19 positive convalescent patients. We determined that 97.7% of the analyzed convalescent sera maintained the presence of NAbs with neutralizing activity, and this activity remained until 10 months after the infection in some cases. In addition, the relationship between the presence of NAbs and immunoglobulin G was significant compared to immunoglobulin M, which tended to be absent over time.