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Publications (8)80.8 Total impact

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    ABSTRACT: BACKGROUND: The global spread of the 2009 novel pandemic influenza A (H1N1) virus led to the accelerated production and distribution of monovalent 2009 Influenza A (H1N1) vaccines (pH1N1). This pandemic provided the opportunity to evaluate the risk of Guillain-Barré syndrome (GBS), which has been an influenza vaccine safety concern since the swine flu pandemic of 1976, using a common protocol among high and middle-income countries. The primary objective of this project was to demonstrate the feasibility and utility of global collaboration in the assessment of vaccine safety, including countries both with and without an established infrastructure for vaccine active safety surveillance. A second objective, included a priori, was to assess the risk of GBS following pH1N1 vaccination. METHODS: The primary analysis used the self-controlled case series (SCCS) design to estimate the relative incidence (RI) of GBS in the 42 days following vaccination with pH1N1 vaccine in a pooled analysis across databases and in analysis using a meta-analytic approach. RESULTS: We found a relative incidence of GBS of 2.42 (95% CI 1.58-3.72) in the 42 days following exposure to pH1N1 vaccine in analysis of pooled data and 2.09 (95% CI 1.28-3.42) using the meta-analytic approach. CONCLUSIONS: This study demonstrates that international collaboration to evaluate serious outcomes using a common protocol is feasible. The significance and consistency of our findings support a conclusion of an association between 2009 and 2010 H1N1 vaccination and GBS. Given the rarity of the event the relative incidence found does not provide evidence in contradiction to international recommendations for the continued use of influenza vaccines.
    Vaccine 06/2013; · 3.77 Impact Factor
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    ABSTRACT: Guillain-Barré Syndrome (GBS) can be triggered by gastrointestinal or respiratory infections, including influenza. During the 2009 influenza A (H1N1) pandemic in the United States, monovalent inactivated influenza vaccine (MIV) availability coincided with high rates of wildtype influenza infections. Several prior studies suggested an elevated GBS risk following MIV, but adjustment for antecedent infection was limited. We identified patients enrolled in health plans participating in the Vaccine Safety Datalink and diagnosed with GBS from July 2009 through June 2011. Medical records of GBS cases with 2009-10 MIV, 2010-11 trivalent inactivated influenza vaccine (TIV), and/or a medically-attended respiratory or gastrointestinal infection in the 1 through 141 days prior to GBS diagnosis were reviewed and classified according to Brighton Collaboration criteria for diagnostic certainty. Using a case-centered design, logistic regression models adjusted for patient-level time-varying sources of confounding, including seasonal vaccinations and infections in GBS cases and population-level controls. Eighteen confirmed GBS cases received vaccination in the 6 weeks preceding onset, among 1.27 million 2009-10 MIV recipients and 2.80 million 2010-11 TIV recipients. Forty-four confirmed GBS cases had infection in the 6 weeks preceding onset, among 3.77 million patients diagnosed with medically-attended infection. The observed-versus-expected odds that 2009-10 MIV/2010-11 TIV was received in the 6 weeks preceding GBS onset was odds ratio = 1.54, 95% confidence interval (CI), 0.59-3.99; risk difference = 0.93 per million doses, 95% CI, -0.71-5.16. The association between GBS and medically-attended infection was: odds ratio = 7.73, 95% CI, 3.60-16.61; risk difference = 11.62 per million infected patients, 95% CI, 4.49-26.94. These findings were consistent in sensitivity analyses using alternative infection definitions and risk intervals for prior vaccination shorter than 6 weeks. After adjusting for antecedent infections, we found no evidence for an elevated GBS risk following 2009-10 MIV/2010-11 TIV influenza vaccines. However, the association between GBS and antecedent infection was strongly elevated.
    PLoS ONE 01/2013; 8(6):e67185. · 3.53 Impact Factor
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    ABSTRACT: Background/Aim: We describe the incidence of Guillain-Barré syndrome (GBS) in a large United States cohort. Methods: Between 2000 and 2009, we identified visits with an ICD-9 code for GBS (357.0) from all persons with continuous enrollment for at least 1 year. The primary case definition was restricted to emergency department and inpatient visits. We calculated age-standardized rates and used multivariate Poisson regression to assess variation in rates by sex, age, season and year of diagnosis. We tabulated descriptive characteristics and the positive predictive value (PPV) for a subset of the visits with available medical record review. Results: 1,619 visits with the GBS ICD-9 code were identified from 50,290,898 person-years of observation. After considering the PPV (55%) for record-reviewed visits, the age-standardized incidence rate was approximately 1.72/100,000 person-years. The rate was 40% higher for males and increased by 50% for every 10-year increase in age. The rate was 15% higher in winter and spring compared with summer. Rates were higher in more recent years. Conclusions: GBS rates are higher in males and increase considerably with age. The potential reasons for differences in rates by season and the increased rates in more recent years should be further investigated.
    Neuroepidemiology 07/2012; 39(2):109-15. · 2.37 Impact Factor
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    ABSTRACT: The Post-Licensure Rapid Immunization Safety Monitoring (PRISM) system is a cohort-based active surveillance network initiated by the US Department of Health and Human Services to supplement preexisting and other vaccine safety monitoring systems in tracking the safety of monovalent pandemic 2009 H1N1 influenza vaccine in the United States during 2009-2010. PRISM investigators conducted retrospective analysis to determine whether 2009 H1N1 vaccination was associated with increased risk of any of 14 prespecified outcomes. Five health insurance and associated companies with 38 million members and 9 state/city immunization registries contributed records on more than 2.6 million doses of 2009 H1N1 vaccine. Data on outcomes came from insurance claims. Complementary designs (self-controlled risk interval, case-centered, and current-vs.-historical comparison) were used to optimize control for confounding and statistical power. The self-controlled risk interval analysis of chart-confirmed Guillain-Barré syndrome found an elevated but not statistically significant incidence rate ratio following receipt of inactivated 2009 H1N1 vaccine (incidence rate ratio = 2.50, 95% confidence interval: 0.42, 15.0) and no cases following live attenuated 2009 H1N1 vaccine. The study did not control for infection prior to Guillain-Barré syndrome, which may have been a confounder. The risks of other health outcomes of interest were generally not significantly elevated after 2009 H1N1 vaccination.
    American journal of epidemiology 05/2012; 175(11):1120-8. · 5.59 Impact Factor
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    ABSTRACT: An increased risk of Guillain-Barré syndrome (GBS) following administration of the 1976 swine influenza vaccine led to a heightened focus on GBS when monovalent vaccines against a novel influenza A (H1N1) virus of swine origin were introduced in 2009. GBS cases following receipt of monovalent inactivated (MIV) and seasonal trivalent inactivated (TIV) influenza vaccines in the Vaccine Safety Datalink Project in 2009-2010 were identified in electronic data and confirmed by medical record review. Within 1-42 days following vaccination, 9 cases were confirmed in MIV recipients (1.48 million doses), and 8 cases were confirmed in TIV-only recipients who did not also receive MIV during 2009-2010 (1.72 million doses). Five cases following MIV and 1 case following TIV-only had an antecedent respiratory infection, a known GBS risk factor; furthermore, unlike TIV, MIV administration was concurrent with heightened influenza activity. In a self-controlled risk interval analysis comparing GBS onset within 1-42 days following MIV with GBS onset 43-127 days following MIV, the risk difference was 5.0 cases per million doses (95% confidence interval: 0.5, 9.5). No statistically significant increased GBS risk was found within 1-42 days following TIV-only vaccination versus 43-84 days following vaccination (risk difference = 1.1 cases per million doses, 95% confidence interval: -3.1, 5.4). Further evaluation to assess GBS risk following both vaccination and respiratory infection is warranted.
    American journal of epidemiology 05/2012; 175(11):1100-9. · 5.59 Impact Factor
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    ABSTRACT: Current rotavirus vaccines were not associated with intussusception in large prelicensure trials. However, recent postlicensure data from international settings suggest the possibility of a low-level elevated risk, primarily in the first week after the first vaccine dose. To examine the risk of intussusception following pentavalent rotavirus vaccine (RV5) in US infants. This cohort study included infants 4 to 34 weeks of age, enrolled in the Vaccine Safety Datalink (VSD) who received RV5 from May 2006-February 2010. We calculated standardized incidence ratios (SIRs), relative risks (RRs), and 95% confidence intervals for the association between intussusception and RV5 by comparing the rates of intussusception in infants who had received RV5 with the rates of intussusception in infants who received other recommended vaccines without concomitant RV5 during the concurrent period and with the expected number of intussusception visits based on background rates assessed prior to US licensure of the RV5 (2001-2005). Intussusception occurring in the 1- to 7-day and 1- to 30-day risk windows following RV5 vaccination. During the study period, 786,725 total RV5 doses, which included 309,844 first doses, were administered. We did not observe a statistically significant increased risk of intussusception with RV5 for either comparison group following any dose in either the 1- to 7-day or 1- to 30-day risk window. For the 1- to 30-day window following all RV5 doses, we observed 21 cases of intussusception compared with 20.9 expected cases (SIR, 1.01; 95% CI, 0.62-1.54); following dose 1, we observed 7 cases compared with 5.7 expected cases (SIR, 1.23; 95% CI, 0.5-2.54). For the 1- to 7-day window following all RV5 doses, we observed 4 cases compared with 4.3 expected cases (SIR, 0.92; 95% CI, 0.25-2.36); for dose 1, we observed 1 case compared with 0.8 expected case (SIR, 1.21; 95% CI, 0.03-6.75). The upper 95% CI limit of the SIR (6.75) from the historical comparison translates to an upper limit for the attributable risk of 1 intussusception case per 65,287 RV5 dose-1 recipients. Among US infants aged 4 to 34 weeks who received RV5, the risk of intussusception was not increased compared with infants who did not receive the rotavirus vaccine.
    JAMA The Journal of the American Medical Association 02/2012; 307(6):598-604. · 29.98 Impact Factor
  • JAMA The Journal of the American Medical Association 01/2012; · 29.98 Impact Factor
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    ABSTRACT: Background and Aims: The worldwide introduction of influenza A (H1N1) vaccines in fall 2009 has raised widespread public questions about the safety of these new vaccines. The Vaccine Safety Datalink Project, a collaboration among CDC and eight health care systems in the HMORN, began accelerated monitoring of this vaccine’s safety in early fall 2009.
    Clinical Medicine &amp Research 12/2010;