Family Characteristics Associated with Likelihood of Varicella Vaccination.

Context: The introduction of the varicella vaccine as a routine pediatric immunization in the US, in 1995, provided an opportunity to assess factors associated with uptake of new vaccines in the member population of the Kaiser Permanente Northwest (KPNW) Health Plan.

Objective: Identify factors associated with varicella vaccination in the KPNW population in the first five years after varicella vaccine was introduced.

Design: A retrospective cohort of children under age 13 years between June 1995 and December 1999, without a history of varicella disease was identified using KPNW automated data.

Positive Predictive Value of ICD-9 Code for Herpes Zoster Among Children During the Varicella Vaccine Era.

We examined the positive predictive value of the herpes zoster ICD-9 diagnosis code 053 in the Kaiser Permanente Northwest integrated health plan. Among children 0-17 years old, the positive predictive value was 87.1% (95% confidence interval: 84.

A Ten-Year Case-Control Study of Passive Smoke Exposure as a Risk Factor for Pertussis in Children.

The authors conducted a matched case-control study of laboratory-confirmed pertussis cases, occurring from 1/1/1996 to 12/31/2005, in children up to 12 years of age who were members of a large managed care organization. Sixty-five laboratoryconfirmed cases of pertussis were identified. Using multivariable conditional logistic regression analysis, the authors did not detect a statistically significant association between pertussis and household passive exposure to cigarette smoking.

Passive cigarette smoke exposure and other risk factors for invasive pneumococcal disease in children: a case-control study.

Objective: To investigate whether passive cigarette smoke exposure increases the risk of invasive pneumococcal disease in children.

Methods: In a population-based case-control study, 171 children aged 0 to 12 years with culture-confirmed invasive pneumococcal disease during the years 1994 to 2004 were identified. Two controls were matched to each case on age and patterns of Health Plan membership.

Wheezing lower respiratory disease and vaccination of premature infants.

Purpose: Premature infants are at increased risk of wheezing in association with respiratory syncytial virus (RSV) and rhinovirus infections. We assess possible associations between wheezing and routine vaccinations of premature infants.

Methods: We conducted a self-controlled case series (SCCS) study of premature infants born at five health maintenance organizations (HMO's) from 1997 to 2002 (N=18,628).

Identifying optimal risk windows for self-controlled case series studies of vaccine safety.

In vaccine safety studies, subjects are considered at increased risk for adverse events for a period of time after vaccination known as risk window. To our knowledge, risk windows for vaccine safety studies have tended to be pre-defined and not to use information from the current study. Inaccurate specification of the risk window can result in either including the true control period in the risk window or including some of the risk window in the control period, which can introduce bias.

Laboratory characteristics of suspected herpes zoster in vaccinated children.

Varicella vaccination of children has decreased varicella disease incidence, but introduced the occurrence of herpes zoster (HZ) from vaccine-type virus. We identified 14 vaccinated children with suspected HZ and confirmed varicella virus by polymerase chain reaction in 6 cases. Two cases were due to vaccine-type virus.

Frequency of medically attended events following rapid revaccination with trivalent inactivated influenza vaccine.

In 2008, potential temperature compromise of one lot of trivalent inactivated influenza vaccine (TIV) led to the revaccination of 13,210 Kaiser Permanente Northwest members within 28 days of receipt of their initial TIV dose. We conducted a retrospective cohort study to determine if these individuals experienced a higher rate of medically attended events (MAE) than those receiving only one TIV dose. We found no increase in MAE among those rapidly revaccinated (odds ratio 1.

Henoch-Schölein purpura and polysaccharide meningococcal vaccine.

Background: We describe here a case of Henoch-Schönlein purpura (HSP) that occurred 10 days after administration of the meningococcal polysaccharide vaccine and came to the attention of a Vaccine Safety Datalink (VSD) investigator (but did not occur in the VSD cohort). Periodic case reports have linked vaccines to HSP.

Objective: To better understand the potential risk for HSP after immunization with the meningococcal polysaccharide vaccine.

Multiple vaccinations and the risk of medically attended fever.

Recent increases in the number of vaccinations recommended for infants have triggered concerns about the safety of multiple vaccinations. This study evaluated rates of medically attended fever after infant vaccination using computerized data from 1991 to 2000 from two large U.S.

Influenza vaccination coverage among adult solid organ transplant recipients at three health maintenance organizations, 1995-2005.

Annual immunization against influenza is recommended for solid organ transplant (SOT) recipients. We used Vaccine Safety Datalink data from 1995 to 2005 to assess influenza vaccination during the first full vaccination season (September-February) following transplant among 1800 kidney, liver, and heart transplant recipients at three health maintenance organizations. Overall, 52% of recipients were vaccinated.

Detecting possible vaccine adverse events in clinical notes of the electronic medical record.

The Vaccine Safety Datalink (VSD) is a collaboration between the CDC and eight large HMOs to investigate adverse events following immunization through analyses of clinical data. We modified an existing system, called MediClass, that uses natural language processing to identify clinical events recorded in electronic medical records (EMRs). We customized MediClass so it could detect possible vaccine adverse events (VAEs) generally, and gastrointestinal-related VAEs in particular, in the text clinical notes of encounters recorded in the EMR of a large HMO.

Medicaid coverage, methadone maintenance, and felony arrests: outcomes of opiate treatment in two states.

A modest number of clinics in Oregon and Washington provide MMT maintenance treatment (MMT) services. More than 10,000 clients in each state were followed for 3 years after an initial admission for opiate use between 1993 and 2000. Medicaid clients in both states had far greater access to MMT than their non-Medicaid counterparts, controlling for differences in client characteristics using propensity scores.

Predictive value of ICD-9-CM codes used in vaccine safety research.

Objectives: To assess how well selected ICD-9-CM diagnosis codes predict adverse events; to model bias and power loss when vaccine safety analyses rely on unverified codes.

Methods: We extracted chart verification data for ICD-9-CM diagnosis codes from six Vaccine Safety Datalink (VSD) publications and modeled biases and power losses using positive predictive value (PPV) estimates and ranges of code sensitivity.

Results: Positive predictive values were high for type 1 diabetes (80%) in children, relative to WHO criteria, and intussusception (81%) in young children, relative to a standard published case definition.

Comparison of epidemiologic methods for active surveillance of vaccine safety.

Objective: We performed a simulation study to compare four study designs [(matched-cohort, vaccinated-only (risk-interval) cohort, case-control, and self-controlled case-series (SCCS)] in the context of vaccine safety active surveillance.

Methods: For each combination of various incidence levels (3, 30, 300 per 10(5) person-years) and relative risks (RR 1.5-18), 100 case sets were infused into the cohort, matching 10(5) vaccinated to 10(5) unvaccinated on age and gender.

Laboratory diagnosis and characteristics of breakthrough varicella in children.

The atypical features of varicella in vaccinated persons (breakthrough varicella [BTV]) present diagnostic challenges. We examined varicella-zoster virus (VZV) polymerase chain reaction (PCR) and immunoglobulin (Ig) M and IgG serologic test results for confirming BTV cases. Among 33 vaccinated children with varicella-like rash, we identified wild-type VZV in 58% overall and in 76% of those with adequate tissue specimens; no vaccine-type virus was found.

Risk of immune thrombocytopenic purpura after measles-mumps-rubella immunization in children.

Background: The measles-mumps-rubella vaccine has been associated with immune thrombocytopenia purpura in 2 small studies.

Methods: By using the Vaccine Safety Datalink, we identified measles-mumps-rubella-vaccinated children aged 1 to 18. A case of immune thrombocytopenia purpura was defined as a patient with a platelet count of < or = 50,000/microL with clinical bleeding and normal red and white blood cell indices.

Effectiveness of influenza vaccine in the community-dwelling elderly.

Background: Reliable estimates of the effectiveness of influenza vaccine among persons 65 years of age and older are important for informed vaccination policies and programs. Short-term studies may provide misleading pictures of long-term benefits, and residual confounding may have biased past results. This study examined the effectiveness of influenza vaccine in seniors over the long term while addressing potential bias and residual confounding in the results.

Hepatitis B vaccine and risk of autoimmune thyroid disease: a Vaccine Safety Datalink study.

Purpose: Hepatitis B vaccine has been postulated as a possible cause of autoimmune disorders, including autoimmune thyroid diseases (ATD). Cases of Graves' disease and Hashimoto's thyroiditis, following hepatitis B vaccine have been reported to the Vaccine Adverse Events Reporting System (VAERS). To test the hypothesis that hepatitis B vaccine increases the risk of ATD, we conducted a case-control study, within the Vaccine Safety Datalink project.

Impact of maternal influenza vaccination during pregnancy on the incidence of acute respiratory illness visits among infants.

Objective: To determine whether influenza vaccination of pregnant women prevents visits for respiratory illness in their infants born during the influenza season.

Design: Retrospective matched cohort study.

Setting: Four managed care organizations in the United States.

Variation in hepatitis B immunization coverage rates associated with provider practices after the temporary suspension of the birth dose.

Background: In 1999, the American Academy of Pediatrics and U.S. Public Health Service recommended suspending the birth dose of hepatitis B vaccine due to concerns about potential mercury exposure.

Compliance with the recommendations for 2 doses of trivalent inactivated influenza vaccine in children less than 9 years of age receiving influenza vaccine for the first time: a Vaccine Safety Datalink study.

Objectives: Children <9 years of age do not respond optimally to a first dose of trivalent inactivated influenza vaccine, and so 2 doses of trivalent inactivated influenza vaccine are recommended for children <9 years of age who are being vaccinated for the first time. We conducted a population-based retrospective cohort study to evaluate compliance with the 2-dose trivalent inactivated influenza vaccine recommendations.

Population And Setting: We evaluated 125,928 children 6 months through 8 years of age who were enrolled in health maintenance organizations in the United States participating in the Vaccine Safety Datalink project and who received their first dose of trivalent inactivated influenza vaccine in the 2001-2002, 2002-2003, or 2003-2004 influenza seasons.

Influenza- and RSV-associated hospitalizations among adults.

We estimated influenza- and respiratory syncytial virus (RSV)-associated hospitalizations by age, high-risk status and outcome, during the 1996/1997-1999/2000 respiratory seasons among adults who did not receive influenza vaccine. Using three health maintenance organization (HMO) databases and local viral surveillance data, we identified weeks when influenza and RSV were circulating and estimated influenza- and RSV-associated hospitalizations. Persons aged > or = 65 years with and without high-risk conditions had significantly increased rates of influenza-associated hospitalizations for pneumonia and influenza, and circulatory and respiratory diseases.

Safety of trivalent inactivated influenza vaccine in children 6 to 23 months old.

Context: Beginning with the winter season of 2004-2005, influenza vaccination has been recommended for all children 6 to 23 months old in the United States. However, its safety in young children has not been adequately studied in large populations.

Objective: To screen for medically attended events in the clinic, emergency department, or hospital after administration of trivalent inactivated influenza vaccine in children 6 to 23 months old.