Summary

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• Vaxzevria (COVID-19 vaccine, ChAdOx1-S [recombinant]) is indicated for active immunization of individuals 18 years of age and older for the prevention of coronavirus disease 2019 (COVID-19).
• This summary is based on the review of 14 systematic review(s)/meta-analysis(es). ^[1-14]
• Overall Effectiveness: mRNA vaccines and the AstraZeneca COVID-19 vaccine (ChAdOx1 nCoV-19) showed high effectiveness in patients with autoimmune rheumatic diseases (ARD); however, effectiveness was suboptimal in patients on specific disease-modifying medications and older individuals with interstitial lung diseases.
• Effectiveness Against Variants: Ad26.COV2.S and ChAdOx1 nCoV-19 vaccines were ineffective against the Delta and B.1.351 variants, respectively. Baseline vaccine effectiveness for the Omicron variant was significantly lower compared to other variants.
• Long-term Effectiveness: After the primary vaccine series, effectiveness declined from 83% to 62% for infections, from 92% to 79% for hospitalizations, and from 91% to 86% for mortality. Booster dose effectiveness decreased from 70% to 43% for infections and from 89% to 71% for hospitalizations over 112 days.
• Effectiveness Against Severe Disease: Vaccine efficacy against severe disease remained high (>70%) over time, although efficacy against symptomatic disease decreased by 20-30 percentage points within six months.
• In patients with autoimmune rheumatic diseases (ARD), most adverse events post-vaccination were self-limiting with minimal reports of disease flares.
• Thrombotic events, including vaccine-induced immune thrombotic thrombocytopenia (VITT), were frequently associated with ChAdOx1 nCoV-19 and Ad26.COV2.S vaccines, often presenting with cerebral venous thrombosis (CVT), deep vein thrombosis (DVT), pulmonary embolism (PE), and significant mortality (~32%).
• Neurological complications such as transverse myelitis (TM) were primarily reported with ChAdOx1 nCoV-19, with older age and higher modified Rankin Scale (MRS) scores at admission being risk factors for poor recovery.
• There is no population type or subgroup information available in the reviewed studies.