side effects of first and second doses of inactivated covid-19 vaccine in multiple sclerosis

Background: it is currently recommended to vaccinate against sars cov-2 for people with multiple sclerosis (ms), but it is uncertain what effect it will have on people with ms (pwms).objectives: we aimed to compare the side effects of the first and second doses of the sinopharm vaccine in pwms.materials & methods: this descriptive-analytical follow-up study was conducted on pwms patients in kermanshah province, iran, who received the sinopharm vaccine using the nationwide ms registry of iran (nmsri) by available methods between may and august 2021. using a researcher-made questionnaire, demographic and clinical information about pwms, as well as side effects from the sinopharm vaccine were collected by telephone 5-14 days after the first and second doses. data were analyzed using spss software version 25.results: study participants included 188 pwms, including 148 females (78.7%) and 40 males (21.3%). pwms had median age of 42.66±11.1 years and median 9.57±7.0 for disease duration. in the 1st dose, the prevalence of side effects was significantly higher than in the second dose (58.5% vs 47.0%, p=0.012). fatigue (30.1%), myalgia (29.8%), fever (25.0%), and headache (22.3%) were the most common in the first dose, and fatigue (27.1%), headache (18.6%), myalgia (17.5%) and fever (14.9%) were the most common in the second dose. covid-19 was present in 51 people (27.3%) before vaccination.conclusion: sinopharm vaccine side effects were significantly more prevalent in the first dose than in the second dose. most side effects are moderate in severity and transient.