New IgM seroconversion and positive RT-PCR test after exposure to the virus in recovered COVID-19 patient.

To date, understanding whether acquired immunity and presence of anti SARS-Cov2 antibodies protects against reinfection is one the most important focus of the scientific community [1-2]. Several studies suggest that acquired immunity may protect upon further exposure to SARS-COV2 [3-6]. Contrary to this picture, we describe a case of a patient recovered from COVID-19 pneumonia with positive serology, followed up by 6 negative nasopharyngeal swab-PCR tests performed along 1 month, who later on, after exposure to the virus, presented another positive RT-PCR test and a second IgM seroconversion. This report opens up several possible interpretations. This article is protected by copyright. All rights reserved.