BACKGROUND: In 2011, the Georgia Department of Public Health added varicella to the state’s Notifiable Disease list, mandating physicians, laboratories, and other health care providers to report varicella cases to public health. This report summarizes the first four full years of case-based varicella surveillance in Georgia.
METHODS: A retrospective analysis of all varicella cases reported to the State Electronic Notifiable Disease Surveillance System (SENDSS) was conducted for the years 2012-2015. Cases were considered confirmed if they met the Council of State and Territorial Epidemiologists standard varicella case definition of an illness characterized by acute onset of a diffuse papulovesicular rash without other known cause, with the recognition that the rash in vaccinated persons may be atypical with few or no vesicles, and were either laboratory confirmed or epidemiologically linked to another case. Cases were classified as probable if they met the clinical case definition but were not laboratory confirmed or epidemiologically linked.
RESULTS: Between 2012 and 2015, 586 cases of varicella (370 probable and 216 confirmed) were reported in Georgia. Two cases were hospitalized and 1 died. Most cases (58.9%) were vaccinated – 130 (22.1%) had received one dose, and 215 (36.7%) had received 2 doses of varicella vaccine prior to illness onset, while 241 (41.4%) were unvaccinated. Among unvaccinated cases, 75 (31.1%) were below the age recommendation. Overall, most cases occurred in 5-9 year olds (31.6%), followed by 1-4 year olds (25.8%). Unvaccinated case-patients reported fever (58%) more frequently and 50 – 249 lesions (48.8%) compared to those with one dose (43.4% fever, 64.6% < 50 lesions) or two doses (20.9% fever, 63.3% < 50 lesions). Median duration of rash did not vary with vaccination status (6-7 days). Median number of months from most recent varicella vaccination until breakthrough illness onset was 22.9 for cases after one dose, and 45.3 for cases which occurred after two doses. After one vaccine dose, 28/130 (21.5%) developed illness within 42 days of vaccination; only 5/214 (2.3%) developed illness within 42 days after 2 doses.
CONCLUSIONS: Varicella cases reported in Georgia during 2012-2015 remained highest in the primary school years despite mandatory 2 dose vaccination prior to school entry since 2006. Vaccinated persons who developed breakthrough illness had fewer lesions and were less likely to develop fever, although their rash duration remained similar to unvaccinated cases. Breakthrough disease was documented to occur from months to years after vaccination and occurred later following two doses of varicella vaccine.