Biomedical subjects
Jane Seward
Publications and source records attributed to Jane Seward.
Varicella seroprevalence and molecular epidemiology of varicella-zoster virus in Argentina, 2002.
There is limited data on immunity against varicella-zoster virus (VZV) in adults in different parts of Argentina, and it is not known which VZV strains are circulating in Argentina. The objectives of this study were as follows: (i) to evaluate seroprevalence of varicella among adults, assessing the accuracy of clinical history and determining the sociodemographic factors associated with seropositivity; and (ii) to determine the VZV strains circulating in Argentina. A cross-sectional serological survey enrolling 2,807 women aged 15 to 49 years attending public health-care settings in four cities in Argentina (i.e., Buenos Aires, Salta, Mendoza, and Rosario) and one rural area was conducted from August to November 2002. Specimens for identification of VZV strains were obtained from vesicular lesions from 13 pediatric patients with varicella from different areas of the country. PCR amplification was used for genotyping. The overall seroprevalence of varicella antibodies was 98.5% (95% confidence interval, 98.0 to 98.9), ranging from 97.2% in central Buenos Aires to 99.3% in southern Buenos Aires and Salta. Varicella seroprevalence increased with age. Crowding and length of residence in the same place were associated with seropositivity. The positive predictive value of varicella history for immunity to varicella was 99.4%; however, the negative predictive value was 2.5%. The European genotype was identified in all viral specimens. In Argentina, seroprevalence in women more than 15 years old was high regardless of the area of residence. Negative or uncertain varicella history was not a good predictor of immunity. VZV genotype was stable in all areas of the country.
Varicella susceptibility and validity of history among U.S. Coast Guard recruits: an outbreak-based study.
During a varicella outbreak among U.S. Coast Guard recruits, we examined varicella susceptibility serologically and evaluated validity of disease history. Recruits completed a questionnaire to obtain information on demographics, history of varicella disease, and varicella vaccination. Serological testing for varicella-zoster virus immunoglobulin G antibodies was conducted using an enzyme-linked immunosorbant assay. Among 513 recruits, 21 (4.1%) were seronegative to varicella-zoster virus. Recruits born in Puerto Rico were more likely than recruits born in the U.S. states to be susceptible (prevalence ratio, 4.3; 95% confidence interval, 1.4%, 13.1%). A positive disease history was highly predictive of positive serology (99.1%); however, 73% of those with a negative or uncertain history were also immune. Four (19%) susceptible recruits reported a positive varicella history. Although immunity among recruits was high, varicella outbreaks may occur in closed adult settings due to the high risks of exposure and transmission. Varicella vaccination can prevent these costly, disruptive outbreaks.
Outbreak of varicella at a day-care center despite vaccination.
BACKGROUND: In seven studies of the effectiveness of the varicella vaccine conducted since it was licensed, the effectiveness was 71 to 100 percent against disease of any severity and 95 to 100 percent against moderate and severe disease. We investigated an outbreak of varicella in a population of children with a high proportion of vaccinees who were attending a day-care center in a small community in New Hampshire. METHODS: Using standardized questionnaires, we collected information about the children's medical and vaccination history from parents and health care providers. The analysis of the effectiveness of the vaccine and of risk factors for vaccine failure was restricted to children who were enrolled in the day-care center continuously during the outbreak and attended for one week or more and who were cared for in the building that represented the epicenter of the outbreak, since transmission was not documented in a second building. RESULTS: Varicella developed in 25 of 88 children (28.4 percent) between December 1, 2000, and January 11, 2001. The index case occurred in a healthy child who had been vaccinated three years previously and who infected more than 50 percent of his classmates who had no history of varicella. The effectiveness of the vaccine was 44.0 percent (95 percent confidence interval, 6.9 to 66.3 percent) against disease of any severity and 86.0 percent (95 percent confidence interval, 38.7 to 96.8 percent) against moderate or severe disease. Children who had been vaccinated three years or more before the outbreak were at greater risk for vaccine failure than those who had been vaccinated more recently (relative risk, 2.6 [95 percent confidence interval, 1.3 to 5.3]). CONCLUSIONS: In this outbreak, vaccination provided poor protection against varicella, although there was good protection against moderate or severe disease. A longer interval since vaccination was associated with an increased risk of vaccine failure. Breakthrough infections in vaccinated, healthy persons can be as infectious as varicella in unvaccinated persons.
Younger age at vaccination may increase risk of varicella vaccine failure.
To determine vaccine effectiveness (VE), a varicella outbreak in a highly vaccinated day-care center (DCC) population in Pennsylvania was investigated. In Pennsylvania, proof of immunity is required for children >or=12 months old for DCC enrollment. Questionnaires were administered to parents of children who had attended the DCC continuously during the study period (1 November 1999-9 April 2000) to determine history of varicella disease or vaccination and for information about any recent rash illnesses. VE was calculated for children >or=12 months old without a history of varicella. There were 41 cases of varicella among 131 attendees, with 14 cases (34%) among vaccinated children. VE was 79% against all varicella and 95% against moderate or severe varicella. Vaccination at <14 months was associated with an increased risk of breakthrough disease (relative risk, 3.0; 95% confidence interval, 0.9-9.9). Despite varicella vaccination coverage of 80%, a sizeable outbreak occurred. Early age at vaccination may increase the risk of vaccine failure.
Hospitalizations for varicella in the United States, 1988 to 1999.
BACKGROUND: Varicella epidemiology is changing with increasing use of the varicella vaccine. METHODS: To describe the epidemiology of severe varicella disease before and after vaccine introduction, data from the National Hospital Discharge Survey (NHDS) for 1988 to 1999 were analyzed. Incidental cases of varicella in persons hospitalized for a different indication were excluded. RESULTS: In the prevaccination era (1988 to 1995), there were 10 632 varicella hospitalizations annually. The most common complications were viral pneumonitis (20.9%), fluid/electrolyte disturbances (19.3%) and soft tissue infections (17.8%). Most (89.1%) persons had no severe underlying immunocompromising conditions. The mean length of hospitalization was 5.4 days, corresponding to approximately 57 000 days of hospitalization annually. In the first years after vaccine licensure (1996 to 1999), vaccine coverage reached 59%. Although not statistically significant, there was a trend toward decreased hospitalizations and a decline in mean length of hospitalization. CONCLUSIONS: Varicella morbidity was higher in the prevaccination era than previously reported. Although no significant decline is evident, a trend toward decreased hospitalizations is emerging in the first years after vaccine introduction.
Second varicella infections: are they more common than previously thought?
OBJECTIVE: To describe the epidemiology and clinical characteristics of varicella reinfections reported to a surveillance project. METHODS: We investigated varicella cases reported to a surveillance project between January 1, 1995, and December 31, 1999--with more extensive investigation of cases reporting previous varicella with onset between January 1, 1998, and September 30, 1998--to provide a more detailed description of first and second varicella infections. A simple decision tree was used to assess the likelihood that reported first and second infections were varicella. RESULTS: Among varicella cases reported to the surveillance project, 4.5% of cases in 1995 and 13.3% of cases in 1999 reported previous varicella. More than 95% of first infections were physician diagnosed, epidemiologically linked to another case, or had a rash description consistent with varicella; the same was true for reported second infections. People who reported reinfections were generally healthy. There was a family history of repeat infections in 45% of people who reported reinfections. CONCLUSIONS: Clinical varicella reinfections may occur more commonly than previously thought. Additional studies of the predictive value of a positive varicella history and laboratory studies of reported reinfections are indicated to guide varicella vaccination policy.
Tracking varicella deaths: accuracy and completeness of death certificates and hospital discharge records, New York State, 1989-1995.
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Congenital rubella syndrome burden in Morocco: a rapid retrospective assessment.
BACKGROUND: WHO recommends that countries considering introduction of rubella vaccine into their immunisation programme assess their burden of congenital rubella syndrome, to determine whether vaccination is warranted. However, few guidelines exist for such assessments in developing countries. We retrospectively estimated the burden of congenital rubella syndrome in Morocco, and assessed our methods of rapid case finding. METHODS: We undertook case finding in the two cities with Morocco's main tertiary care referral centres, using medical records from births between Jan 1, 1990, and May 31, 2002, disability records from 1965 to 1997, and retinal examinations from deaf students born between 1985 and 1994, applying the WHO definition for a clinically confirmed case of congenital rubella syndrome. We also reviewed disability data for evidence of epidemic periodicity and estimated yearly incidence of the syndrome from congenital cataract data for births between 1990 and 2001. FINDINGS: We identified 62 clinically confirmed cases of congenital rubella syndrome from medical records, 148 from disability records, and 15 in deaf students. We noted no epidemic periodicity in disability data, and estimated a yearly incidence of the syndrome in Morocco of 8.1-12.7 cases per 100000 livebirths. INTERPRETATION: We show evidence of congenital rubella syndrome in Morocco and support the addition of rubella vaccination to the national programme. Various data sources can be explored to rapidly assess burden of the syndrome; ophthalmology departments and outpatient cardiology clinics could offer the most potential for such case finding, dependent on documentation practices.