ABSTRACT
BackgroundThrombosis with thrombocytopenia syndrome (TTS) is a potentially life-threatening condition associated with adenoviral-vectored COVID-19 vaccination. TTS presents similarly to autoimmune heparin-induced thrombocytopenia. Twelve cases of cerebral venous sinus thrombosis following Janssen/Johnson & Johnson (Ad26.COV2.S) COVID-19 vaccination have been described. ObjectiveDescribe surveillance data and reporting rates of TTS cases following COVID-19 vaccination. DesignCase series. SettingUnited States PatientsCase-patients reported to the Vaccine Adverse Event Reporting System (VAERS) receiving COVID-19 vaccine from December 14, 2020 through August 31, 2021, with thrombocytopenia and thrombosis (excluding isolated ischemic stroke or myocardial infarction). If thrombosis was only in an extremity vein or pulmonary embolism, a positive enzyme-linked immunosorbent assay for anti-platelet factor 4 antibody was required. MeasurementsReporting rates (cases/million vaccine doses) and descriptive epidemiology. Results52 TTS cases were confirmed following Ad26.COV2.S (n=50) or mRNA-based COVID-19 (n=2) vaccination. TTS reporting rates were 3.55 per million (Ad26.COV2.S) and 0.0057 per million (mRNA-based COVID-19 vaccines). Median age of patients with TTS following Ad26.COV2.S vaccination was 43.5 years (range: 18-70); 70% were female. Both TTS cases following mRNA-based COVID-19 vaccination occurred in males aged >50 years. All cases following Ad26.COV2.S vaccination involved hospitalization including 32 (64%) with intensive care unit admission. Outcomes of hospitalizations following Ad26.COV2.S vaccination included death (12%), discharge to post-acute care (16%), and discharge home (72%). LimitationsUnder-reporting and incomplete case follow-up. ConclusionTTS is a rare but serious adverse event associated with Ad26.COV2.S vaccination. The different demographic characteristics of the two cases reported after mRNA-based COVID-19 vaccines and the much lower reporting rate suggest that these cases represent a background rate. Funding SourceCDC
ABSTRACT
BackgroundIn December 2020, two mRNA-based COVID-19 vaccines were authorized for use in the United States. Vaccine safety was monitored using the Vaccine Adverse Event Reporting System (VAERS), a passive surveillance system, and v-safe, an active surveillance system. MethodsVAERS and v-safe data during December 14, 2020--June 14, 2021 were analyzed. VAERS reports were categorized as non-serious, serious, or death; reporting rates were calculated. Rates of reported deaths were compared to expected mortality rates by age. Proportions of v-safe participants reporting local and systemic reactions or health impacts the week following doses 1 and 2 were determined. FindingsDuring the analytic period, 298,792,852 doses of mRNA vaccines were administered in the United States. VAERS processed 340,522 reports; 92{middle dot}1% were non-serious; 6{middle dot}6%, serious, non-death; and 1{middle dot}3%, death. Over half of 7,914,583 v-safe participants self-reported local and systemic reactogenicity, more frequently after dose 2. Injection-site pain, fatigue, and headache were commonly reported during days 0-7 following vaccination. Reactogenicity was reported most frequently one day after vaccination; most reactions were mild. More reports of being unable to work or do normal activities occurred after dose 2 (32{middle dot}1%) than dose 1 (11{middle dot}9%); <1% of participants reported seeking medical care after vaccination. Rates of deaths reported to VAERS were lower than expected background rates by age group. InterpretationSafety data from >298 million doses of mRNA COVID-19 vaccine administered in the first 6 months of the U.S. vaccination program show the majority of reported adverse events were mild and short in duration.
