ABSTRACT
BACKGROUND: Adults previously infected with SARS-CoV-2 develop short-term immunity and may have increased reactogenicity to COVID-19 vaccines. This prospective, multi-center active surveillance cohort study examined the short-term safety of COVID-19 vaccines in adults with a prior history of SARS-CoV-2. METHODS: Canadian adults vaccinated between December 22, 2020 and November 27, 2021 were sent an electronic questionnaire 7 days post dose 1, dose 2 and dose 3 vaccination. The main outcome was health events occurring in the first 7 days after each vaccination that prevented daily activities, resulted in work absenteeism or required a medical consultation, including hospitalization. RESULTS: Among 684,998 vaccinated individuals, 2.6% (18,127/684,998) reported a prior history of SARS-CoV-2 infection a median of 4 months (interquartile range 2-6 months) previously. After dose 1, individuals with moderate (bedridden) to severe (hospitalized) COVID-19 who received BNT162b2, mRNA1273 or ChAdox1-S vaccines had higher odds of a health event preventing daily activities, resulting in work absenteeism or requiring medical consultation; adjusted odds ratio (AOR) 3.96 (95% CI 3.67-4.28) for BNT162b2, 5.01 (4.57-5.50) for mRNA1273 and 1.84 (1.54-2.20) for ChAdox1-S compared to no infection. Following dose 2 and 3, the greater risk associated with previous infection was also present but attenuated compared to dose 1. For all doses, the association was lower or absent after mild or asymptomatic infection. CONCLUSION: Adults with moderate or severe previous SARS-CoV-2 infection were more likely to have a health event sufficient to impact routine activities or require medical assessment in the week following each vaccine doses.
ABSTRACT
BACKGROUND: The devastating impact of the SARS-CoV-2 pandemic prompted the development and emergency use authorization of two mRNA vaccines in early 2020. Vaccine trials excluded nursing home (NH) residents, limiting adverse event data that directly apply to this population. METHODS: To prospectively monitor for potential adverse events associated with vaccination, we used Electronic Health Record (EHR) data from Genesis HealthCare, the largest NH provider in the United States. EHR data on vaccinations and pre-specified adverse events were updated daily and monitored for signal detection among residents of 147 facilities who received the first dose of vaccine between December 18, 2020 and January 3, 2021. For comparison, unvaccinated residents during the same time period were included from 137 facilities that started vaccinating at least 15 days after the vaccinating-facilities. RESULTS: As of January 3, 2021, 8553 NH residents had received one dose of SARS-CoV-2 vaccine and by February 20, 2021, 8371 residents had received their second dose of vaccine; 11,072 were included in the unvaccinated comparator group. No significant associations were noted for neurologic outcomes, anaphylaxis, or cardiac events. CONCLUSIONS: No major safety problems were detected following the first or second dose of the vaccine to prevent COVID-19 in the study cohort from December 18, 2020 through March 7, 2021.