Gregory S. Wallace

Pertussis Hospitalizations Among Infants in the United States, 1993 to 2004

OBJECTIVE. We sought to describe the rates of pertussis hospitalization among infants by using databases that do not rely on passive reporting and compare with results obtained from the passive national surveillance system. METHODS. The incidence of infant pertussis hospitalization in 1993 to 2004 was determined by using 2 national hospitalization discharge databases (Nationwide Inpatient Sample and Kids’ Inpatient Database) and the National Notifiable Disease Surveillance System/Supplemental Pertussis Surveillance System. Rates were determined for separate age groups among infants <1 year of age. Pertussis complications and procedures were examined by using the Kids’ Inpatient Database. RESULTS. In 1993 to 2004, the pertussis hospitalization rates for infants ≤2 months of age were generally stable, by the discharge databases. The incidence of infant pertussis hospitalization obtained from the Nationwide Inpatient Sample and Kids’ Inpatient Database was ∼2 times greater than that obtained from the passive reporting system. Infants 1 to 2 months of age had the highest incidence (239 hospitalizations per 100000 live births in the 2003 Kids’ Inpatient Database). An annual average of 2678 hospitalizations occurred in 2000 and 2003; 86% occurred in infants ≤3 months of age. Among those with ages provided, 95% of infants who required mechanical ventilation and all of those who died were ≤3 months of age. CONCLUSIONS. Pertussis hospitalization incidence rates among the youngest infants were generally stable in 1993 to 2004 and were highest for infants 1 to 2 months of age. The impact of the new adolescent and adult tetanus-diphtheria-acellular pertussis vaccines on infant pertussis should be monitored through such discharge databases. Additional vaccination strategies should be evaluated to protect infants as early in life as possible.

Vaccine-Derived Poliomyelitis 12 Years after Infection in Minnesota

A 44-year-old woman with long-standing common variable immunodeficiency who was receiving intravenous immune globulin suddenly had paralysis of all four limbs and the respiratory muscles, resulting in death. Type 2 vaccine-derived poliovirus was isolated from stool. The viral capsid protein VP1 region had diverged from the vaccine strain at 12.3% of nucleotide positions, and the two attenuating substitutions had reverted to the wild-type sequence. Infection probably occurred 11.9 years earlier (95% confidence interval [CI], 10.9 to 13.2), when her child received the oral poliovirus vaccine. No secondary cases were identified among close contacts or 2038 screened health care workers. Patients with common variable immunodeficiency can be chronically infected with poliovirus, and poliomyelitis can develop despite treatment with intravenous immune globulin.

Financing vaccination of children and adolescents: National Vaccine Advisory Committee recommendations

Increases in the number and cost of vaccines routinely recommended for children and adolescents have raised concerns about the ability of the current systems for vaccine financing and delivery to ensure that all children and adolescents have access to all routinely recommended vaccinations without financial barriers. The National Vaccine Advisory Committee (NVAC) was chartered in 1988 to advise and to make recommendations to the director of the National Vaccine Program and the Assistant Secretary for Health at the US Department of Health and Human Services on matters related to the prevention of infectious diseases through vaccination. In October 2006, NVAC established a Vaccine Financing Working Group to explore approaches for child and adolescent vaccine financing. The Vaccine Financing Working Group was charged with establishing a process for obtaining stakeholder input regarding challenges to creating optimal approaches to vaccine financing in both the public and private sectors. The goal of this process was to develop recommendations to ensure that all children and adolescents have access to all routinely recommended vaccinations without financial barriers.

Seroprevalence of Measles, Mumps, Rubella and Varicella Antibodies in the United States Population, 2009–2010

Background. In the United States, measles, mumps, rubella, and varicella immunity is now primarily achieved through vaccination. Monitoring population immunity is necessary. Methods. We evaluated seroprevalence of antibodies to measles, mumps, rubella, and varicella using the National Health and Nutrition Examination Survey during 2009–2010. Results. Measles, mumps, rubella, and varicella seroprevalence was 92.0% (95% confidence interval [CI], 90.9%−93.0%), 87.6% (CI, 85.8%−89.2%), 95.3% (CI, 94.3%−96.2%), and 97.8% (CI, 97.1%−98.3%), respectively. United States (US)-born persons had lower mumps seroprevalence and higher varicella seroprevalence than non-US born persons. Conclusions. Seroprevalence was high (88%–98%) for all 4 viruses in the US population during 2009−2010.

Mumps postexposure prophylaxis with a third dose of measles-mumps-rubella vaccine, Orange County, New York, USA.

Although the measles-mumps-rubella (MMR) vaccine is not recommended for mumps postexposure prophylaxis (PEP), data on its effectiveness are limited. During the 2009–2010 mumps outbreak in the northeastern United States, we assessed effectiveness of PEP with a third dose of MMR vaccine among contacts in Orthodox Jewish households who were given a third dose within 5 days of mumps onset in the household’s index patient. We compared mumps attack rates between persons who received a third MMR dose during the first incubation period after onset in the index patient and 2-dose vaccinated persons who had not. Twenty-eight (11.7%) of 239 eligible household members received a third MMR dose as PEP. Mumps attack rates were 0% among third-dose recipients versus 5.2% among 2-dose recipients without PEP (p = 0.57). Although a third MMR dose administered as PEP did not have a significant effect, it may offer some benefits in specific outbreak contexts.

A Comparison of Postelimination Measles Epidemiology in the United States, 2009-2014 Versus 2001-2008.

Background Measles, a vaccine-preventable disease that can cause severe complications, was declared eliminated from the United States in 2000. The last published summary of US measles epidemiology was during 2001-2008. We summarized US measles epidemiology during 2009-2014. Methods We compared demographic, vaccination, and virologic data on confirmed measles cases reported to the Centers for Disease Control and Prevention during January 1, 2009-December 31, 2014 and January 1, 2001-December 31, 2008. Results During 2009-2014, 1264 confirmed measles cases were reported in the United States, including 275 importations from 58 countries and 66 outbreaks. The annual median number of cases and outbreaks during this period was 130 (range, 55-667 cases) and 10 (range, 4-23 outbreaks), respectively, compared with an annual median of 56 cases (P = .08) and 4 outbreaks during 2001-2008 (P = .04). Among US-resident case-patients during 2009-2014, children aged 12-15 months had the highest measles incidence (65 cases; 8.3 cases/million person-years), and infants aged 6-11 months had the second highest incidence (86 cases; 7.3 cases/million person-years). During 2009-2014, 865 (74%) of 1173 US-resident case-patients were unvaccinated and 188 (16%) had unknown vaccination status; of 917 vaccine-eligible US-resident case-patients, 600 (65%) were reported as having philosophical or religious objections to vaccination. Conclusions Although the United States has maintained measles elimination since 2000, measles outbreaks continue to occur globally, resulting in imported cases and potential spread. The annual median number of cases and outbreaks more than doubled during 2009-2014 compared with the earlier postelimination years. To maintain elimination, it will be necessary to maintain high 2-dose vaccination coverage, continue case-based surveillance, and monitor the patterns and rates of vaccine exemption.

Risk factors for transmission of mumps in a highly vaccinated population in Orange County, NY, 2009-2010.

Background: In 2009–2010, we investigated a mumps outbreak among a highly vaccinated Orthodox Jewish population in a village in Orange County, NY, to identify risk factors associated with mumps transmission among persons with 2 doses of mumps-containing vaccine. Methods: Demographic and epidemiologic characteristics were collected on students in grades 6–12 in 3 schools. A mumps case was defined as a student, who self-reported parotitis, orchitis, jaw swelling and/or a mumps-related complication or whose mumps illness was reported to the Orange County Health Department during September 1, 2009, to January 18, 2010. Log-binomial regression analyses were conducted separately for boys and girls as they attended different schools and had different hours of study. Results: Of the 2503 students with 2 documented doses of mumps-containing vaccine, 320 (13%) developed mumps. Risk of mumps increased with increasing number of mumps cases in the class [≥8 vs. ⩽3 cases: boys aRR = 3.1; 95% confidence interval (CI): 2.0–5.0; girls aRR = 2.6; 95% CI: 1.6–4.1] and household (>1 vs. 0 cases: boys aRR = 4.3 95% CI: 3.7–5.6; girls aRR = 10.1 95% CI: 7.1–14.3). Age at first dose, time since last dose, time between first and second dose, school, class size, number of hours at school per week and household size were not significantly associated with having mumps. Conclusions: Two doses of mumps-containing vaccine may not be as effective in outbreak settings with multiple, prolonged and intense exposure. Additional studies are required to understand why such mumps outbreaks occur and how they can be prevented in the future.

Knowledge of Interim Recommendations and Use of Hib Vaccine During Vaccine Shortages

OBJECTIVES: The goals were to determine among pediatricians and family physicians (1) knowledge of interim recommendations regarding Haemophilus influenzae type b (Hib) vaccine administration, (2) current practices, and (3) factors associated with nonadherence. METHODS: An Internet-based survey was conducted in April 2008 among national samples. RESULTS: Response rates were 68% (220 of 325 physicians) among pediatricians and 51% (153 of 302 physicians) among family physicians. Seventy-three percent of pediatricians and 45% of family medicine physicians reported insufficient Hib vaccine supplies, and 22% to 24% reported having to defer doses for infants 2 to 6 months of age ≥10% of the time. Ninety-eight percent of pediatricians and 81% of family physicians were aware of the interim recommendations (P ≤ .0001), and virtually all knew that the booster dose should be deferred; however, 22% of pediatricians and 33% of family medicine physicians reported not deferring this dose. Physicians in both specialties were less likely to adhere to recommendations to defer in this age group if they thought that their practice had sufficient vaccine supplies (pediatricians, odds ratio: 0.01 [95% confidence interval: 0.003–0.03]; family medicine physicians, odds ratio: 0.10 [95% confidence interval: 0.03–0.33]). Family medicine physicians were less likely to adhere to recommendations if they had not heard about the interim recommendations (odds ratio: 0.04 [95% confidence interval: 0.01–0.21]). CONCLUSIONS: Most primary care physicians experienced Hib vaccine shortages, and many have had to defer doses for 2- to 6-month-old children. Most are knowledgeable regarding interim recommendations, but one-fifth to one-third reported nonadherence.

Incidence of Measles in the United States, 2001-2015

Incidence of Measles in the United States, 2001-2015 Through nationwide use of vaccination, endemic measles (ie, a transmission chain lasting 12 months or longer) was eliminated in the United States in 2000.1 Yet, importations of measles from endemic countries continue to occur, leading to outbreaks.2 We describe the incidence of measles among US residents and examine temporal trends after elimination.

Assessment of the Status of Measles Elimination in the United States, 2001-2014.

Abstract We assessed the status of measles elimination in the United States using outbreak notification data. Measles transmissibility was assessed by estimation of the reproduction number, R, the average number of secondary cases per infection, using 4 methods; elimination requires maintaining R at <1. Method 1 estimates R as 1 minus the proportion of cases that are imported. Methods 2 and 3 estimate R by fitting a model of the spread of infection to data on the sizes and generations of chains of transmission, respectively. Method 4 assesses transmissibility before public health interventions, by estimating R for the case with the earliest symptom onset in each cluster (Rindex). During 2001–2014, R and Rindex estimates obtained using methods 1–4 were 0.72 (95% confidence interval (CI): 0.68, 0.76), 0.66 (95% CI: 0.62, 0.70), 0.45 (95% CI: 0.40, 0.49), and 0.63 (95% CI: 0.57, 0.69), respectively. Year-to-year variability in the values of R and Rindex and an increase in transmissibility in recent years were noted with all methods. Elimination of endemic measles transmission is maintained in the United States. A suggested increase in measles transmissibility since elimination warrants continued monitoring and emphasizes the importance of high measles vaccination coverage throughout the population.