COVID-19 Vaccine AstraZeneca

by Editorial Board last updated 2021-12-03 09:45:46.510672-05:00
Vaxvevria, AZD1222 or ChAdOx1, Covishield (India)



  • COVID-19 Vaccine AstraZeneca

Authorized for Use in

  • Health Canada, EU EMA, UK, WHO EUL, Australia TGA
  • U.S. FDA EUA application date now uncertain.


  • ≥ 18 yrs. Trial for age 12-17 yrs currently paused. Many countries not using in adults under 60 due to thrombosis AE.


  • Nonreplicating chimpanzee adenovirus vector

Primary Dosing

  • 0.5 mL IM; 2 doses 4-12 wks apart (UK & EU), 4 wks in US trial, 8-12 weeks under WHO EUL

Booster Dosing

  • No application in process. Booster recommendations are generally to use an mRNA vaccine


  • CDC recommends that persons aged ≥ 18 years (including moderately or severely immunocompromised persons who received an additional primary dose) who were fully vaccinated with a WHO EUL vaccine not authorized/approved by US FDA or with a heterologous series composed of any FDA-authorized/approved or WHO EUL authorized vaccine are eligible to receive a single booster dose of the Pfizer vaccine (0.3 mL; 30 µg) at least 6 months after completion of their primary series under the existing age guidelines as for Moderna and Pfizer vaccines. Practically, either mRNA vaccine may be used for a booster in this situation.


  • 2-8°C for 4-5 months. After puncture store at 2-25oC for 6 hours


Overall against symptomatic disease

  • 76% (US trial; n=33,000). 62% based on UK approval using other heterogeneous results from multiple combined trials. 82.4% if dose 2 given >12 weeks after dose 1.
    • Overall Efficacy against symptomatic disease in Phase 3 trials pre-delta. Specific VE data against beta, gamma no longer relevant.

Real world against hospitalization

  • 60% VE against symptomatic disease from delta, compared to 66% VE against alpha.

Age > 65 years

  • 80%


  • Not approved

Against severe disease / death

  • Approx 100% in Phase 3 trials (pre-delta)

Against asymptomatic infection / transmission

  • 65% (pre-Delta)

Duration of efficacy after final dose

  • Duration against delta variant especially in immunocompromised and elderly is unknown and of concern.



  • Anaphylactic reaction to a vaccine constituent


  • Women aged <50 years should be educated about the rare risk of thrombosis with thrombocytopenia syndrome (TTS) with the Astra Zeneca vaccine as well as the availability of alternative COVID-19 vaccines to guide joint vaccine decisionmaking with the provider.
  • Postpone vaccination in persons with acute severe febrile illness. Rx with IVIG, N Engl J Med 385:720-8, 2021

Not contraindications

  • No data

Adverse effects

  • Injection-site pain, fatigue, headache, fever, and weakness.
  • TTS in 1:25,000 to 1: 100,000 vaccinees in Europe.
  • No data yet on overall rate of PF4 antibodies or thrombocytopenia. N Engl J Med 2021, 384:2124

Special Needs Populations


  • Unknown

Immunocompromised / HIV

  • Insufficient data