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Vaccine Breakthrough Infections

A COVID-19 vaccine breakthrough infection is defined as a SARS-CoV-2 infection that occurs 14 or more days after a person has completed all the recommended doses of their COVID-19 vaccine (not including boosters). COVID-19 vaccine breakthrough cases are identified by actively matching Alabama case records with Alabama vaccination records.

What We Know

  • COVID-19 vaccines are successful in preventing most infections, however, no vaccine is 100% effective, therefore, breakthrough cases are expected. The number of vaccine breakthrough infections will increase with an increase in the number of fully vaccinated people.
  • The risk of infection, hospitalization, and death are much lower in vaccinated people compared to unvaccinated people, so we recommend that everyone 5 and up should get vaccinated to protect themselves and others.
  • People with a breakthrough infection can spread it to others.

What does this have to do with variants?

  • The Centers for Disease Control and Prevention (CDC) continues to actively monitor vaccine safety and effectiveness against new and emerging variants.
  • Within the U.S., research shows that FDA-authorized vaccines show protection against severe disease, hospitalization, and death caused by currently circulating variants.

How are breakthrough infections monitored?

The CDC has multiple surveillance systems and ongoing research studies to monitor the performance of vaccines in preventing infection, disease, hospitalization, and death including COVID-NET, an important system utilized by the CDC to track vaccine breakthrough infections, and voluntary reporting by state health departments. ADPH is one of the volunteer state health departments reporting vaccine breakthrough data to the CDC.


As of: December 16, 2021
Dates: April 1 - December 15, 2021

  • Vaccine breakthrough cases: 45,407
  • Vaccine breakthrough deaths: 669
  • COVID-19 cases: 330,509
  • COVID-19 deaths: 5,364
  • Fully vaccinated individuals: 2,085,793

Out of 330,509 COVID-19 cases in Alabamians, 13.7% (45,407) were in fully vaccinated people.

Out of 5,364 COVID-19 deaths in Alabamians, 12.5% (669) were in fully vaccinated people.

Out of the 2,085,793 fully vaccinated Alabamians, 2.2% (45,407) contracted COVID-19.

Additional Resources

Page last updated: February 7, 2022