COVID-19 Vaccination Coverage and Associated Factors in Patients with Multiple Sclerosis.

Our objective was to know the COVID-19 vaccination coverage in multiple sclerosis (MS) patients and its factors associated. A retrospective cohort study was carried out. Patients seen at the MS unit of the University Clinical Hospital of Zaragoza between 2017 and 2021 were included. Variables were obtained by reviewing the specialized and primary care records. Associations between receiving COVID-19 full primo-vaccination, as well as one booster dose since autumn 2022, and the other variables were analyzed using bivariate analysis and multiple logistic regression models. Of the 359 included patients, 90.3% received the COVID-19 full primo-vaccination. Having been born in Spain (a OR = 3.40) and having received the 2020-2021 influenza vaccine (a OR = 6.77) were associated with receiving the COVID-19 full primo-vaccination. Vaccination with a COVID-19 booster dose was detected in 141 patients (39.3%). Sex (man) (a OR = 2.36), age (60 years or over) (a OR = 6.82), type of MS (Primary Progressive/Secondary Progressive) (a OR = 3.94), and having received the 2022-2023 influenza vaccine (a OR = 27.54) were associated with receiving such a booster dose. The COVID-19 booster dose was administered at the same time as the 2022-2023 influenza vaccine in 57.8% (67/116) of the patients vaccinated with both vaccines. The COVID-19 full primo-vaccination coverage is higher than in other countries. However, the decrease in vaccination coverage with the booster dose makes it necessary to develop strategies to improve it that are not limited to administering the flu vaccine together with the COVID-19 booster dose. Such strategies should be in focus, especially for women under 60 years of age.