Adriana S. Lopez

The Impact of the Varicella Vaccination Program on Herpes Zoster Epidemiology in the United States: A Review

Speculation that a universal varicella vaccination program might lead to an increase in herpes zoster (HZ) incidence has been supported by modeling studies that assume that exposure to varicella boosts immunity and protects against reactivation of varicella-zoster virus (VZV) as HZ. Such studies predict an increase in HZ incidence until the adult population becomes predominantly composed of individuals with vaccine-induced immunity who do not harbor wild-type VZV. In the United States, a varicella vaccination program was implemented in 1995. Since then, studies monitoring HZ incidence have shown inconsistent findings: 2 studies have shown no increase in overall incidence, whereas 1 study has shown an increase. Studies from Canada and the United Kingdom have shown increasing rates of HZ incidence in the absence of a varicella vaccination program. Data suggest that heretofore unidentified risk factors for HZ also are changing over time. Further studies are needed to identify these factors, to isolate possible additional effects from a varicella vaccination program. Untangling the contribution of these different factors on HZ epidemiology will be challenging.

Impact of a Routine Two-Dose Varicella Vaccination Program on Varicella Epidemiology

OBJECTIVE: One-dose varicella vaccination for children was introduced in the United States in 1995. In 2006, a second dose was recommended to further decrease varicella disease and outbreaks. We describe the impact of the 2-dose vaccination program on varicella incidence, severity, and outbreaks in 2 varicella active surveillance areas. METHODS: We examined varicella incidence rates and disease characteristics in Antelope Valley (AV), CA, and West Philadelphia, PA, and varicella outbreak characteristics in AV during 1995–2010. RESULTS: In 2010, varicella incidence was 0.3 cases per 1000 population in AV and 0.1 cases per 1000 population in West Philadelphia: 76% and 67% declines, respectively, since 2006 and 98% declines in both sites since 1995; incidence declined in all age groups during 2006–2010. From 2006–2010, 61.7% of case patients in both surveillance areas had been vaccinated with 1 dose of varicella vaccine and 7.5% with 2 doses. Most vaccinated case patients had <50 lesions with no statistically significant differences among 1- and 2-dose cases (62.8% and 70.3%, respectively). Varicella-related hospitalizations during 2006–2010 declined >40% compared with 2002–2005 and >85% compared with 1995–1998. Twelve varicella outbreaks occurred in AV during 2007–2010, compared with 47 during 2003–2006 and 236 during 1995–1998 (P < .01). CONCLUSIONS: Varicella incidence, hospitalizations, and outbreaks in 2 active surveillance areas declined substantially during the first 5 years of the 2-dose varicella vaccination program. Declines in incidence across all ages, including infants who are not eligible for varicella vaccination, and adults, in whom vaccination levels are low, provide evidence of the benefit of high levels of immunity in the population.

Acute Flaccid Myelitis in the United States, August–December 2014: Results of Nationwide Surveillance

BACKGROUND During late summer/fall 2014, pediatric cases of acute flaccid myelitis (AFM) occurred in the United States, coincident with a national outbreak of enterovirus D68 (EV-D68)-associated severe respiratory illness. METHODS Clinicians and health departments reported standardized clinical, epidemiologic, and radiologic information on AFM cases to the Centers for Disease Control and Prevention (CDC), and submitted biological samples for testing. Cases were ≤21 years old, with acute onset of limb weakness 1 August-31 December 2014 and spinal magnetic resonance imaging (MRI) showing lesions predominantly restricted to gray matter. RESULTS From August through December 2014, 120 AFM cases were reported from 34 states. Median age was 7.1 years (interquartile range, 4.8-12.1 years); 59% were male. Most experienced respiratory (81%) or febrile (64%) illness before limb weakness onset. MRI abnormalities were predominantly in the cervical spinal cord (103/118). All but 1 case was hospitalized; none died. Cerebrospinal fluid (CSF) pleocytosis (>5 white blood cells/µL) was common (81%). At CDC, 1 CSF specimen was positive for EV-D68 and Epstein-Barr virus by real-time polymerase chain reaction, although the specimen had >3000 red blood cells/µL. The most common virus detected in upper respiratory tract specimens was EV-D68 (from 20%, and 47% with specimen collected ≤7 days from respiratory illness/fever onset). Continued surveillance in 2015 identified 16 AFM cases reported from 13 states. CONCLUSIONS Epidemiologic data suggest this AFM cluster was likely associated with the large outbreak of EV-D68-associated respiratory illness, although direct laboratory evidence linking AFM with EV-D68 remains inconclusive. Continued surveillance will help define the incidence, epidemiology, and etiology of AFM.

Transmission of Varicella Zoster Virus From Individuals With Herpes Zoster or Varicella in School and Day Care Settings

BACKGROUND Because the varicella incidence has declined following varicella vaccine licensure, herpes zoster (HZ) cases may play a larger role in varicella zoster virus (VZV) transmission. We investigated how HZ and varicella cases contribute to the varicella incidence in schools and day care centers. METHODS Surveillance data collected in Philadelphia during September 2003-June 2010 were analyzed. A varicella case was considered to be sporadic if it was reported from a school or day care facility >6 weeks after or ≥10 days before other reports of VZV transmission. A varicella case was considered to be secondary if it occurred 10-21 days after report of a case of HZ or sporadic varicella. Analysis compared VZV transmission from individuals with HZ or sporadic varicella, stratified by varicella vaccination status and disease severity. RESULTS Of 290 HZ cases reported, 27 (9%) resulted in 84 secondary varicella cases. Of 1358 sporadic varicella cases reported, 205 (15%) resulted in 564 secondary varicella cases. Approximately half of the HZ and sporadic varicella cases resulted in single secondary cases. The proportion of individuals who had secondary cases with mild disease was similar for those exposed to HZ and those exposed to varicella (70% and 72%, respectively). VZV transmission was highest from unvaccinated individuals with sporadic varicella (P < .01). CONCLUSIONS VZV transmission from individuals with HZ contributes to varicella morbidity. More research is needed to understand risk factors and guide recommendations for preventing VZV transmission from individuals with HZ.

Challenges in confirming a varicella outbreak in the two-dose vaccine era

BACKGROUND A second dose of varicella vaccine was recommended for U.S. children in 2006. We investigated a suspected varicella outbreak in School District X, Texas to determine 2-dose varicella vaccine effectiveness (VE). METHODS A varicella case was defined as an illness with maculopapulovesicular rash without other explanation with onset during April 1-June 10, 2011, in a School District X student. We conducted a retrospective cohort in the two schools with the majority of cases. Lesion, saliva, and environmental specimens were collected for varicella-zoster virus (VZV) PCR testing. VE was calculated using historic attack rates among unvaccinated. RESULTS In School District X, 82 varicella cases were reported, including 60 from Schools A and B. All cases were mild, with a median of 14 lesions. All 10 clinical specimens and 58 environmental samples tested negative for VZV. Two-dose varicella vaccination coverage was 66.4% in Schools A and B. Varicella VE in affected classrooms was 80.9% (95% CI: 67.2-88.9) among 1-dose vaccinees and 94.7% (95% CI: 89.2-97.4) among 2-dose vaccinees in School A, with a second dose incremental VE of 72.1% (95% CI: 39.0-87.3). Varicella VE among School B students did not differ significantly by dose (80.1% vs. 84.2% among 1-dose and 2-dose vaccinees, respectively). CONCLUSION Laboratory testing could not confirm varicella as the etiology of this outbreak; clinical and epidemiologic data suggests varicella as the likely cause. Better diagnostics are needed for diagnosis of varicella in vaccinated individuals so that appropriate outbreak control measures can be implemented.

Varicella Outbreak Reporting, Response, Management, and National Surveillance

Two national surveys were conducted to evaluate the status of varicella case-based surveillance and outbreak response. Although progress toward national surveillance has been significant, a large number of jurisdictions are still without case-based surveillance. For jurisdictions beginning case-based surveillance with limited resources, a staged approach is recommended. The national outbreak survey showed that a significant number of varicella outbreaks continue to occur. The majority of jurisdictions respond to these outbreaks, although the response varies considerably. Depending on the outbreak-response approach, costs per outbreak ranged from

Intelligence and Academic Achievement With Asymptomatic Congenital Cytomegalovirus Infection

3000 for a typical, or passive, response to

Challenges With Controlling Varicella in Prison Settings Experience of California, 2010 to 2011

6000 for a more active response. As varicella surveillance and outbreak control improves, jurisdictions may benefit from more-standardized outbreak-control practices. The recent recommendation by the Advisory Committee on Immunization Practices for a routine second dose of varicella vaccine should lead to better varicella disease control, making case-based surveillance and appropriate outbreak response even more feasible.

Varicella Outbreak Surveillance in Schools in Sentinel Jurisdictions, 2012–2015

Intelligence, language, and academic achievement in children with asymptomatic congenital CMV infection identified through hospital-based newborn screening managed through 18 years of age. OBJECTIVES: To examine intelligence, language, and academic achievement through 18 years of age among children with congenital cytomegalovirus infection identified through hospital-based newborn screening who were asymptomatic at birth compared with uninfected infants. METHODS: We used growth curve modeling to analyze trends in IQ (full-scale, verbal, and nonverbal intelligence), receptive and expressive vocabulary, and academic achievement in math and reading. Separate models were fit for each outcome, modeling the change in overall scores with increasing age for patients with normal hearing (n = 78) or with sensorineural hearing loss (SNHL) diagnosed by 2 years of age (n = 11) and controls (n = 40). RESULTS: Patients with SNHL had full-scale intelligence and receptive vocabulary scores that were 7.0 and 13.1 points lower, respectively, compared with controls, but no significant differences were noted in these scores among patients with normal hearing and controls. No significant differences were noted in scores for verbal and nonverbal intelligence, expressive vocabulary, and academic achievement in math and reading among patients with normal hearing or with SNHL and controls. CONCLUSIONS: Infants with asymptomatic congenital cytomegalovirus infection identified through newborn screening with normal hearing by age 2 years do not appear to have differences in IQ, vocabulary or academic achievement scores during childhood, or adolescence compared with uninfected children.

Serological Susceptibility to Varicella among U.S. Immigration and Customs Enforcement Detainees

This article describes the epidemiology of varicella in one state prison in California during 2010 and 2011, control measures implemented, and associated costs. Eleven varicella cases were reported, of which nine were associated with two outbreaks. One outbreak consisted of three cases and the second consisted of six cases with two generations of spread. Among exposed inmates serologically tested, 98% (643/656) were varicella-zoster virus seropositive. The outbreaks resulted in > 1,000 inmates exposed, 444 staff exposures, and >