What is it?

COVID-19 is a disease caused by SARS-CoV-2

SARS stands for severe acute respiratory syndrome. CoV means coronavirus, which is the family of viruses. 

Common symptoms include fever, chills, cough, loss of taste or smell, fatigue (tiredness), difficulty breathing, and muscle aches.

What's the difference between them?

Pfizer and Moderna are mRNA vaccines, while Johnson and Johnson is an adenovirus vector vaccine. 

For information about these types of vaccines, click here.

Pfizer and Moderna are recommended for people as young as 6 months old. Johnson and Johnson is approved for people over 18. 

Primary series:

  • The mRNA vaccines require 2 doses and Johnson and Johnson requires 1 dose. 

    • 3-8 weeks between doses for Pfizer​

    • 4-8 weeks between doses for Moderna

  • For kids under 5:

    • The Pfizer vaccine requires a 3-dose series with 3-8 weeks between dose 1 and 2 and at least 8 weeks between dose 2 and 3. 

    • Moderna is a 2-dose series with at least 4-8 days between doses

There are also booster doses:

  • People become eligible for boosters 5 months after their second dose of an mRNA vaccine or 2 months after receiving Johnson and Johnson.

  • The Pfizer booster is approved for ages 5+ and the others are approved for 18+.

    • Currently, the mRNA booster options are preferred for most people.

    • Your booster dose does not have to be the same as your first vaccine.

  • People over 50 are eligible for a second booster

Relevant Terms

  • Adenoviruses: a common family of viruses. These viruses can cause cold-like symptoms, conjunctivitis (pink eye), sore throat, and other symptoms. The version used in adenovirus vector vaccines is not able to cause these symptoms and cannot replicate. 

  • Adenovirus vector: a version of an adenovirus that cannot replicate or cause disease. It is used to deliver the genetic information so that the body can make the spike protein.

  • mRNA: Messenger ribonucleic acid (mRNA) is a form of genetic material that acts as a template to make proteins.