Efficacy & Safety of the COVID Vaccines: A Closer Look

Gabrielle Busque

January 15, 2021

Detailed efficacy & safety data for the Pfizer-BioNTech, Moderna, and AstraZeneca-Oxford vaccines.

Efficacy

Pfizer-BioNTech Vaccine

  • First dose efficacy of 85% (95% CI 66-93%) in preventing COVID-19 within 11-21 days after vaccination
  • Second dose efficacy 95% (CI 90-97%) 7 days after vaccination


Moderna Vaccine

  • First dose efficacy of 94% (95% CI 76-99%) starting 14 days after vaccination
  • Second dose efficacy 94.1% 2 weeks after vaccination
  • May be slightly less effective (86.4%; 95% CI 61.4%-95.5%) in older adults 65+


AstraZeneca-Oxford Vaccine

  • First dose efficacy of 64.1% (95% CI 50.5-73.9%) against symptomatic COVID-19 21 days or more after vaccination with one standard dose
  • Second dose efficacy of 70.4% (95% CI 54.8-80.6%) across two dosing regimens (low dose [LD]+ standard dose [SD]; SD + SD)
  • Second dose efficacy of 90% (95% CI 67.4-97%) in LD + SD group
  • Second dose efficacy of 62.1% (95% CI 41-75.7%) in SD + SD group

Sources

Side Effects

Pfizer-BioNTech

Injection site pain (84.1%), fatigue (62.9%), headache (55.1%), muscle pain (38.3%), chills (31.9%), joint pain (23.6%) and fever (14.2%) - all usually mild or moderate in intensity


Moderna

Injection site pain (92.0%), fatigue (70.0%), headache (64.7%), myalgia (61.5%), arthralgia (46.4%), chills (45.4%), nausea/vomiting (23.0%), axillary swelling/tenderness (19.8%), fever (15.5%), swelling at the injection site (14.7%), and erythema at the injection site (10.0%)


AstraZeneca-Oxford

  • Very common (>10%): tenderness, pain, warmth, redness, itching, swelling or bruising where the injection is given, generally feeling unwell, fatigue, chills or feeling feverish, headache, nausea, joint pain or muscle aches
  • Common (10%): a lump at the injection site, fever, vomiting, flu-like symptoms (e.g. high temperature, sore throat, runny nose, cough and chills)
  • Uncommon (1%): feeling dizzy, decreased appetite, abdominal pain, enlarged lymph nodes, excessive sweating, itchy skin, or rash.
  • In clinical trials there were very rare reports of events associated with inflammation of the nervous system, which may cause numbness, pins and needles, and/or loss of feeling. However, it is not confirmed whether these events were due to the vaccine.

Sources

WRITTEN BY:

Gabrielle Busque

Gabrielle is a 4th year pharmacy student at the University of Toronto. At MedMe, Gabrielle is heavily involved in drug/medical information and design. She is passionate about optimizing the delivery of clinical services in pharmacies to advance patient care.

MedMe is a thought leader and software provider in pharmacy care

Sign up for our mailing list to join the community and access monthly newsletters!

Thank you! Your submission has been received!
Oops! Something went wrong while submitting the form.