COVID-19 Vaccine AstraZeneca

Administration

Vaccine

• 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.

Age

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

Type

• 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

Interchangeability

• 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.

Storage

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

Efficacy

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%

Pediatric

• 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.

Toxicities

Contraindications

• Anaphylactic reaction to a vaccine constituent

Precautions

• 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

Pregnancy

• Unknown

Immunocompromised / HIV

• Insufficient data