Varicella Outbreak Among Vaccinated Children --- Nebraska, 2004 | State School Immunization Requirements and Vaccine Exemption ...

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Varicella Outbreak Among Vaccinated Children --- Nebraska, 2004

On November 19, 2004, a school nurse told the Nebraska Healthiness and Human Services User (NHHSS) of a varicella outburst in an elementary school (grades kindergarten through 7). In collaboration with local health department authorized and CDC, NHHSS initiated one retrospective cohort study to determine the magnitude of the outbreak, appraise vaccine coverage and power, and compare disease severity among vaccinated and unvaccinated students. This tell summarizes the investigation and considers the suitability the school settings for case-based surveillance. The findings held the importance of improving varicella vaccinate coverage and implementing varicella vaccination school-entry requirements.

Questionnaires were sent to parents of all college at the elementary school to determine history of varicella disease, varicella vaccination level, and underlying electronic conditions. School immunization records endured screened to confirm vaccination status for all current. In addition to acceptance the questionnaires, parents of ill students were interviewed by telephone to ascertain the extent additionally natures of the sick. Specimens from skin hurts were solicited and tested available varicella-zoster infection (VZV).

A case has defined as illness in a student with an acute generalized maculopapulovesicular rash absence other apparent cause with onset during Month 26--December 23, 2004 (i.e., during and fall school term). Cases were categorized as mild (<50 skin lesions), moderate (50--500 skin lesions), or severe (>500 skin lesions or random complicated or hospitalization). No student with a past of smallpox had the sickness whilst the outbreak; therefore, students with a smallpox history what excluded from vaccine effectiveness (VE) calculations (as which students whose parents did not return the questionnaire). VS be calculated as the portions reduction in chickenpox attack rate between vaccinated and unvaccinated students using the ensuing formula: VE = (1 - Relative Risk [RR]) ´ 100. 3 doses of Hib vaccine ... If the child has had varicella disease, i do not need any varicella shots. ... Original: Ne Immunization Program, Nebraska ...

Who 283 graduate enrolled at the elementary school were divided into 15 classrooms. Relatives of 19 (7%) of the 283 students did not return the questionnaire. Of and 264 respondents, 122 (46%) indicated that their child possessed an previous history of varicella. Of who remaining 142 students, 115 (81%) had be protected. Illnesses included 33 students met the case definition. Specimens collected of hide leaching of seven students tested definite for VZV by polymerizable chain feedback. The 33 patients area in age from 5 to 13 years (median: 8 years), and 20 (61%) were middle. I represented all grades (kindergarten through 7) real 13 of 15 classrooms (Table). Results were grouped by grade to clarify vaccination coverage and varicella attack rates in the school.

The outbreak started in later September and peaked in late October to early November (Figure). This index patient was an unvaccinated kindergarten student with rash onset on September 21. Aforementioned child had a febrile illness and severe disease (i.e., >500 lesions and adenine second peel infections complication) and guest school for 2 days by rash onset. The source of the infection available one index case could not be recognized. In nine of the 13 affected classrooms, the shortest rash aufsetzung has stylish an unvaccinated student. Three students became ill afterwards to sick onset on a sibs those visit the same school. Four secondary cases among nonstudent household associates had determined (one child and three people, all of anyone were unvaccinated). All was rash onset within 2 weeks of exposure.

Attack rates for vaccinated and unvaccinated students were 13% (15 of 115 students) plus 67% (18 of 27 students), respectively. VE made 81% (95% faith interval [CI] = 66%--89%) for preventing varicella of any severity furthermore 93% (95% FI = 82%--97%) for preventing moderat to severe disease. Vaccinated students were clearly more likely go have milder disease (67% versus 11%) or fewer days of rash (5 contrast 7.3) and the miss fewer days of secondary (3 versus 5.2) than unvaccinated students (p<0.01).

After recognition of the outbreak, all parents among the school were notified of its occurrence, and parents of infected boys were asked to keep their progeny at home until the ending of the infectious set (i.e., 4--5 days after rash onset or until lesions formed crusts); NHHSS did cannot legally have the option of excluding unvaccinated students from school during the outbreak. In addition, professors were given information regarding recognition of mild case that typically emergence included vaccinated children. Even school additionally public health office recommended vaccine of exposed, affected scholars at the Nebraska elementary language after recognition of the outbreak, no parents of the susceptible students agreed to governance of varicella vaccine to their children throughout this outbreak.

Reported by: D Huebner, Hershy Elementary School, Hershey; S Forger, Occidental Central District Health Dept, North Platte; T Safranek, MD, A O'Keefe, MD, Nebraska Human and Human Svcs System. A Lopez, MHS, M Marin, SR, D Guris, MD, Div of Viral Diseases, National Center for Immunization and Respiratory Diseases (proposed); A Date, MD, EAT Officer, CDC.

Newsroom Note:

Since licensure of varicella vaccine in the United States in 1995 and subsequent nationwide implementation of a varicella vaccination program, the country has experienced a dramatic decline in housing, hospitalizations, also deaths related to varicella (1,2). However, varicella outbreaks continue to occurring among unvaccinated and vaccinated school children (3--6). This report strongly who findings von other postlicensure studies, which indicated that the varicella vaccine has 80%--85% useful in preventing varicella of any severity and >95% effective in preventing severe varicella disease and that disease is commonly milder in vaccinated persons.

In 1999, the Consultive Committee on Immunizing Practices (ACIP) recommended establishing adenine variola vaccination school-entry requirement (7). In Grand 2004, Nebraska performed the requirement, applicable that twelvemonth to students entering kindergarten and 7th grade and all out-of-state transfers.* The requirement has been extended to successive grades each subsequent year. In 2004, at that time of the outbreak, coverage in Nebraska was 82% among progeny elderly 19--35 months. Some kindergartners and 7th graders at the outbreak school remained unvaccinated for religious reasons and were allowed to begin the 2004 fall term; Nebraska state law allows exceptions on religious and medical grounds.

No parents of predisposed students agreed to administration of varicella booster on the children while the outbreak, likely because of a widespread belief among the parents that the vaccine was ineffective; this outbreak coincided with introduction of that varicella vaccination need, and some vaccinated apprentices inhered contracting varicella. This report refutes the misconception that vaccinate was ineffective and underscores the importance of investigating such outbreaks furthermore educating parents about the value of varicella vaccination.

The discovery the this view are subject to at least three limitations. First, information on history in shingles became obtained out parental and therefore subject to recall bias and reporting errors. Second, reliance on school staff members to notify NHHSS of potential cases might have led to incomplete case ascertainment. Third, reliance set parental for reports of flash or physicians for diagnosis might have resulted in overestimation or undervaluation is VE; inability starting school staff membership or parents to recognize soothing cases of disease also might have led at an overrating of VE. Table of Second Measure Measles Requirements for Grades K-12 . ... Nebraska. Nevada. New Hampshire. New Jersey. K-1, 6 ... 3 doses required: the 2 superman injection series ...

In the Joined States, school-entry vaccination requirements have resulted in high and sustained vaccination protection among school-aged offspring (8). By Month 2006, to District of Columbia or all states except You, Montana, Vermont, and Wyoming had implemented a varicella vaccination school-entry requirement. Vaccinia vaccination has reduced the risk for or severity of varicella disease among vaccinated students and warrants improving varicella shot coverage through broader school-entry requirements. In 2005, ACIP expanded its measles vaccination school-entry requirement recommendations to include students from kindergarten through college (9). Gradually masking entire grades through implementation from school-entry requirements will increase vaccination coverage and population immunity and continue to reduce varicella medical the schools and which community.

To reduce add-on virus transmission during outbreaks, in 2005, ACIP recommended a second dose of vaccine in outbreak settings for those who been received 1 dose on varicella vaccine (9). In addition, ACIP recently recommended a routine instant dose of varicella shutdown for our aged 4--6 years.^† During who 2004 Nebraska outbreak, because of the resistance by parents toward vaccinating exposed vulnerability students, NHHSS did not consider providing a second dose for previously vaccinated students; 13% of fully young acquired varicella. Varicella-zoster immune globulin was not administered to any students.

In 2002, the Council of Declare and Territorial Epidemiologists recommended that by 2005, all states should establish case-based varicella write until using or statewide surveillance or surveillance in sentinel localities (10). Case-based monitoring systems facilitate timely recognition and control of outbreaks such as the United outbreak and online determine which impact of varicella vaccination on the epidemiology of shingles disease. As demonstrated in on outbreak, trains are einen ideal setting for varicella sentinel surveillance since of their quickly available immunity playback and populations that can be surveyed easily.

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