Outbreaks and Public Health Response

Local or state public health officials may investigate clusters or outbreaks of invasive group A Streptococcus (group A strep) infections. The most common clusters investigated in the United States are those occurring in long-term care facilities. Other types of outbreak investigations include:

  • Clusters of pharyngitis (strep throat) among school-aged children
  • Healthcare-associated infections such as postpartum and post-surgical infections
  • Foodborne outbreaks of pharyngitis, although these are rare in the United States

These clusters often require urgent public health action.

Group A Strep Calculator

It can be difficult to determine how much invasive group A strep disease is normal for a specific area over a specific time period. CDC developed the Group A Strep Calculator to help local and state health public health officials determine if the number of invasive group A strep cases seen locally are greater than what would be expected. The calculator estimates the average number of invasive group A strep cases a region should expect. The calculator takes population characteristics into account when estimating the number of expected cases for any one month period. The calculator then compares the locally observed rates to this expected rate. Learn more about the Group A Strep Calculator.

Outbreak Control Measures


There is currently no vaccine to prevent group A strep infections, although several vaccines are in development.


Prophylaxis (pro-fuh-LAK-sis) is when providers give antibiotics to someone to prevent them from getting sick. Most people who are exposed to someone with a group A strep infection should not receive prophylaxis. However, in some situations, providers may recommend prophylaxis for someone exposed to an invasive group A strep infection. Invasive group A strep infections include pneumonia, necrotizing fasciitis and streptococcal toxic shock syndrome.


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