ABSTRACT
OBJECTIVES: AEFIs (adverse events following immunizations), especially ISRR ( immune stress related response) which can cause stroke-like symptoms may affect the vaccine roll-out campaign to prevent the coronavirus 2019 outbreak. METHODS: This study aimed to describe the incidence and clinical characteristics of neurological AEFIs and stroke-like symptoms associated with ISRR after COVID-19 vaccination. Characteristics of ISRR were compared to minor ischemic stroke patients during the same period of the study. During March to September 2021, we retrospectively collected data of participants aged ≥ 18 years who received COVID-19 vaccine and developed AEFIs from Thammasat university vaccination center (TUVC). Data of neurological AEFIs patients and minor ischemic stroke patients were collected from hospital electronic medical record system. RESULTS: COVID-19 vaccine were administered at TUVC for 245,799 doses. AEFIs were reported in 129,652 instances (52.6%). ChADOx-1 nCoV-19 viral vector vaccine has the most frequent occurrence of AEFIs (58.0%), and neurological AEFIs (12.6%). 83% of neurological AEFI was headache. Most were mild and did not need medical attention. Of 119 patients who received COVID-19 vaccine from anywhere with neurological AEFIs and presented to TUH, ISRR was diagnosed in 107 patients (89.9%) and all patients who has follow-up data (30.8%) showed clinical improvement. In comparison with minor ischemic stroke (116 patients), ISRR patients had significantly less ataxia, facial weakness, weakness of arm/leg and speech disturbances (P < 0.001). CONCLUSION: The incidence of neurological AEFIs after COVID-19 vaccination was higher among recipients of ChAdOx-1 nCoV-19 vaccine (12.6%) than inactivated vaccine (6.2%) and mRNA vaccine (7.5%). However, most neurological AEFIs were ISRR, had mild severity and resolved within 30 days. Stroke-like symptoms occurred less frequently than patients with minor ischemic stroke.