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Breakthrough Cases

A vaccine breakthrough infection occurs when a confirmed or probable SARS-CoV-2 infection 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

  • Since no vaccine in 100% effective, breakthrough cases are expected.
  • COVID-19 vaccines are effective at preventing most infections, but if there is a breakthrough case, that individual is less likely to develop serious illness, which means a much less likelihood of hospitalization.

What does this have to do with variants?

  • The more COVID-19 infections, the more breakthrough infections
  • 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 vaccines offer protection against severe disease, hospitalization, and death.
  • 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.

How are breakthrough cases 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 infectionns, and voluntary reporting by state health departments.


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: December 27, 2021