Method: CDC receives reports of hepatitis A infections from states through the National Notifiable Disease Surveillance System (NNDSS) and/or directly to the viral hepatitis outbreak response team. We analyzed NNDSS hepatitis A data for 2007–2016, and a combination of NNDSS data and cases directly reported to the CDC hepatitis A outbreak response team during 2017; excluding 2017 NNDSS data from the four states that directly reported outbreaks to the outbreak response team to eliminate the potential for double-counting cases.
Result: During 2007─2011, a total of 10,619 hepatitis A cases were reported; 521 (5%) were associated with outbreaks. Of the 274 outbreak-associated cases for whom clinical data were reported, 102 (37%) were hospitalized and one (0.3%) died. Of the 407 outbreak-associated cases for whom risk exposure data were reported, 210 (52%) were associated with a common source. Comparatively, during 2012─2017, a total of 11,483 hepatitis A cases were reported; 2,323 (20%) were associated with outbreaks. Of the outbreak-associated cases for whom clinical data were reported, 1,306/2,162 (60%) were hospitalized and 43/2,178 (2%) died. Of the outbreak-associated cases for whom risk exposure data were reported, 379/2188 (17%) were associated with a common source.
Conclusion: In the United States, outbreaks of hepatitis A infections in the decade prior to 2017 were infrequent and typically associated with a common source. Reported cases associated with hepatitis A outbreaks are increasing, along with concurrent increases in hospitalizations and deaths among persons with outbreak-associated infections. Recent outbreaks indicate a decrease in cases associated with a common-source exposure. Decreasing the susceptible population through adherence to childhood vaccination recommendations and targeted vaccination of recommended at-risk groups can prevent future hepatitis A outbreaks of any transmission pattern.
S. Yin, None
P. Weidle, None