Systemic and Neurologic Adverse Events Among 704,003 First-Dose Recipients of the Pfizer-Biontech (BNT162b2) mRNA COVID-19 Vaccine in Mexico (preprint)

ABSTRACT

​Background: The development of mRNA vaccines to prevent SARS-CoV-2 has been remarkably successful, with highly effective vaccines available less than one year after confirming the first case. Due to the global burden of COVID-19 on health systems, emergency approval was attained after clinical trials with relatively small sample sizes and short follow-up periods. Limited information exists about the incidence of adverse events following immunisation (AEFI), particularly neurologic ones. Here, we describe the neurologic AEFI reported by recipients of the BNT162b2 mRNA COVID-19 vaccine. Methods: We conducted a prospective observational cohort using de-identified information from a database of all systemic and neurologic AEFI reported to the Mexican Ministry of Health throughout a passive Epidemiological Surveillance System by first-dose vaccine recipients, from December 24, 2020 to February 12, 2021. The cut-off date for this data was February 18, 2021. We performed descriptive analyses on demographics, timing from vaccination to AEFI development, event duration, and current outcome.Findings: Nationwide, 704 003 first-doses were administered; 6536 AEFI were reported. Among those, 4258 (65·1%) had at least one neurologic manifestation. Non-serious neurologic AEFI occurred in 99·6%. Headache (62·2%), transient sensory symptoms (3·5%), and weakness (1%) were the most frequent. Thirty-three serious AEFI were reported, of which 17 (2·4/100 000 doses) were neurologic, seven seizures, four functional syndromes, three Guillain-Barré syndrome (GBS) cases, and two of acute transverse myelitis. All GBS cases were related to a gastrointestinal infection before vaccination, 3/7 seizure episodes were related to poor antiepileptic drug compliance, and 2/7 to anaphylactic reactions. At the time of this report, 16/17 cases of serious neurologic AEFI had been discharged with no observed deaths.Interpretation: Our data suggest that the BNT162b2 mRNA vaccine is effective and safe. Their individual and societal benefits outweigh the low-percentage of serious neurologic and non-neurologic AEFI.Funding: Consejo Nacional de Ciencia y Tecnología, México.Declaration of Interest None to declareEthical Approval The study was revised and approved by the Ethics and Research Committees of the Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán (Ref. NER-3667-2021) and the Mexican Ministry of Health.