Celebrating 25 Years of Varicella Vaccination Coverage for Children and Adolescents in the United States: A Success Story.

Tracking vaccination coverage is a critical component of monitoring a vaccine program. Three different surveillance systems were used to examine trends in varicella vaccination coverage during the United States vaccination program: National Immunization Survey-Child, National Immunization Survey-Teen, and immunization information systems (IISs). The relationship of these trends to school requirements and disease decline was also examined. Among children aged 19-35 months, ≥1 dose of varicella vaccine increased from 16.0% in 1996 to 89.2% by the end of the 1-dose program in 2006, stabilizing around at least 90.0% thereafter. The uptake of the second dose was rapid after the 2007 recommendation. Two-dose coverage among children aged 7 years at 6 high-performing IIS sites increased from 2.6%-5.5% in 2006 to 86.0%-100.0% in 2020. Among adolescents aged 13-17 years, ≥2-dose coverage increased from 4.1% in 2006 to 91.9% in 2020. The proportion of adolescents with history of varicella disease declined from 69.9% in 2006 to 8.4% in 2020. In 2006, 92% of states and the District of Columbia (DC) had 1-dose daycare or school entry requirements; 88% of states and DC had 2-dose school entry requirements in the 2020-2021 school year. The successes in attaining and maintaining high vaccine coverage were paramount in the dramatic reduction of the varicella burden in the United States over the 25 years of the vaccination program, but opportunities remain to further increase coverage and decrease varicella morbidity and mortality.

Factors contributing to decline in foodborne disease outbreak reports, United States.

The number of foodborne disease outbreaks reported in the United States declined substantially in 2009, when the surveillance system transitioned from reporting only foodborne disease outbreaks to reporting all enteric disease outbreaks. A 2013 survey found that some outbreaks that would have been previously reported as foodborne are now reported as having other transmission modes.