JCV seroconversion rate during the SARS COVID-19 pandemic.

The transmission route of the John Cunningham virus (JCV) is not clearly understood. The high prevalence of JCV in urine and sewage and the stability of the viral particles observed suggest that contaminated water, food, and fomites could be the vehicles of JCV transmission through the oral route. Multiple Sclerosis (MS) patients treated with Natalizumab are at risk of developing progressive multifocal leukoencephalopathy (PML), and hence, JCV serology is monitored for risk stratification. Social restrictions introduced in 2020 which intended to limit the transmission of SARS-CoV-2 are associated with decreased rates of other communicable diseases, as has been shown in recent observational studies. We evaluated the prevalence of seroconversion prior to and during the coronavirus disease (COVID -19) pandemic based on clinical records of JCV serology status in a single-center cohort of Natalizumab-treated Multiple Sclerosis patients. We hypothesized that seroconversion rates would decrease due to behavioral changes. However, seroconversion rates were stable during the COVID-19 pandemic compared to the pre-pandemic. These findings support the notion that JCV is transmitted via the GI tract rather than the respiratory system.