Juventila Liko

Waning Immunity to Pertussis Following 5 Doses of DTaP

OBJECTIVE: To assess the risk of pertussis by time since vaccination in children in Minnesota and Oregon who received 5 doses of acellular pertussis vaccines (DTaP). METHODS: These cohort analyses included Minnesota and Oregon children born between 1998 and 2003 who had 5 DTaP doses recorded in state Immunization Information Systems. Immunization records and statewide pertussis surveillance data were combined. Incidence rates and risk ratios for pertussis were calculated for the 6 years after receipt of the fifth DTaP dose. RESULTS: The cohorts included 224 378 Minnesota children and 179 011 from Oregon; 458 and 89 pertussis cases were identified in Minnesota and Oregon, respectively. Pertussis incidence rates rose each year of follow-up: 15.6/100 000 (95% confidence interval [CI]: 11.1–21.4) at year 1 to 138.4/100 000 (CI: 113.3–166.9) at year 6 (Minnesota); 6.2/100 000 (CI: 3.3–10.6) in year 1 to 24.4/100 000 (CI: 15.0–37.8) in year 6 (Oregon). Risk ratios increased from 1.9 (CI: 1.3–2.9) in year 2 to 8.9 (CI: 6.0–13.0) in year 6 (Minnesota) and from 1.3 (CI: 0.6–2.8) in year 2 to 4.0 (CI: 1.9–8.4) in year 6 (Oregon). CONCLUSIONS: This evaluation reports steady increase in risk of pertussis in the years after completion of the 5-dose DTaP series. This rise is likely attributable in part to waning immunity from DTaP vaccines. Continuing to monitor disease burden and vaccine effectiveness in fully vaccinated children in coming years will be important to assess ongoing risk as additional cohorts vaccinated solely with acellular pertussis vaccines are introduced.

Priming with Whole-Cell versus Acellular Pertussis Vaccine

About 15 years ago, as part of the pediatric series of vaccines for diphtheria, tetanus, and pertussis, a transition from whole-cell to acellular pertussis vaccine occurred. In this report, investigators from Oregon explore the potential effect of this vaccine switch on subsequent pertussis disease.

Sources of Infant Pertussis Infection in the United States

BACKGROUND: Pertussis is poorly controlled, with the highest rates of morbidity and mortality among infants. Although the source of infant pertussis is often unknown, when identified, mothers have historically been the most common reservoir of transmission. Despite high vaccination coverage, disease incidence has been increasing. We examined whether infant source of infection (SOI) has changed in the United States in light of the changing epidemiology. METHODS: Cases <1 year old were identified at Enhanced Pertussis Surveillance sites between January 1, 2006 to December 31, 2013. SOI was collected during patient interview and was defined as a suspected pertussis case in contact with the infant case 7 to 20 days before infant cough onset. RESULTS: A total of 1306 infant cases were identified; 24.2% were <2 months old. An SOI was identified for 569 cases. Infants 0 to 1 months old were more likely to have an SOI identified than 2- to 11-month-olds (54.1% vs 40.2%, respectively; P < .0001). More than 66% of SOIs were immediate family members, most commonly siblings (35.5%), mothers (20.6%), and fathers (10.0%); mothers predominated until the transition to siblings beginning in 2008. Overall, the SOI median age was 14 years (range: 0–74 years); median age for sibling SOIs was 8 years. CONCLUSIONS: In contrast to previous studies, our data suggest that the most common source of transmission to infants is now siblings. While continued monitoring of SOIs will optimize pertussis prevention strategies, recommendations for vaccination during pregnancy should directly increase protection of infants, regardless of SOI.

Pertussis vaccine performance in an epidemic year — Oregon, 2012

A 2012 pertussis epidemic in Oregon afforded an opportunity to measure vaccine effectiveness; it ranged from 95% (95% confidence interval [CI], 92%-97%) among children 15-47 months of age to 47% (95% CI, 19%-65%) among adolescents 13-16 years of age. In all age groups, pertussis incidence was higher among unimmunized persons.

Risk Factors for Pertussis Among Hispanic Infants: Metropolitan Portland, Oregon, 2010-2012.

Background: In 2012, Oregon observed its highest numbers of reported pertussis cases since 1953. The greatest morbidity occurred among infants <6 months of age, with higher rates among Hispanics than non-Hispanics. To explain this disparity, we analyzed pertussis surveillance data. Methods: An analysis was conducted among infants <6 months of age in the Portland metropolitan area during 2010–2012. Characteristics examined were ethnicity (Hispanic or non-Hispanic), household size (>4 or ⩽4 persons), pertussis vaccination status (upto-date or not up-to-date for age), child care center attendance (yes or no), infant birth weight (<2500 or ≥2500 g) and maternal age (<20 or ≥20 years). Results: Eighty-two infants <6 months of age with pertussis were identified. Twenty-eight case-infants (34%) were Hispanic, and 54 (66%) were non-Hispanic. By ethnicity, infants with pertussis were similar in illness confirmation method, sex, age, hospitalization status, vaccination status, child care center attendance, infant birth weight and maternal age. Hispanic infants were more likely than non-Hispanic infants to live in households with >4 persons. Univariate analysis showed Hispanic infants had approximately 2.3 times the risk for pertussis, compared with non-Hispanic infants, and infants living in households >4 persons had approximately 2.4 times the risk for illness, compared with those in households with <4 persons; stratified risk ratios did not differ between Hispanic (2.4; confidence interval: 1.0–5.7]) and non-Hispanic infants (2.0; confidence interval: 1.2–3.5). Conclusions: A household size of >4 persons is a potential risk factor for pertussis; the magnitude of this risk is similar for Hispanic and non-Hispanic infants.

The Timing of Pertussis Cases in Unvaccinated Children in an Outbreak Year: Oregon 2012

Objective To assess whether, during a 2012 pertussis outbreak, unvaccinated and poorly vaccinated cases occurred earlier on a community level. Study design Pediatric pertussis among children 2 months to 10 years of age in the Oregon Sentinel Surveillance region during an epidemic starting at the beginning of 2012 were stratified by immunization status, age, zip code, and calendar date of disease onset. Differences in median onset as days between fully or mostly vaccinated, poorly vaccinated, and unvaccinated cases were examined overall and within local zip code areas. Disease clusters also were examined using SatScan analysis. Results Overall, 351 pertussis cases occurred among children aged 2 months to 10 years of age residing in 72 distinct zipcodes. Among unvaccinated or poorly vaccinated cases, their median date of onset was at calendar day 117 (April 26, 2012), whereas for those who were fully or mostly vaccinated the median date of onset was 41 days later, at day 158 (June 6, 2012). Within each local zip code area, the unvaccinated cases were 3.2 times more likely than vaccinated cases to have earlier median dates of onset (95% CI 2.9‐3.6). Conclusion In this outbreak, pertussis cases among unvaccinated children represented an earlier spread of disease across local areas. Controlling outbreaks may require attention to the composition and location of the unvaccinated.

Notes from the Field: Subacute Sclerosing Panencephalitis Death - Oregon, 2015.

In 2015, the Oregon Health Authority was notified of the death of a boy with subacute sclerosing panencephalitis (SSPE), a rare and fatal complication of measles. The patient, aged 14 years, had reportedly been vaccinated against measles in the Philippines at age 8 months. However, the patient contracted measles at age 1 year while still in the Philippines. He had been well until 2012, when his neurodegenerative symptoms began. After the diagnosis of SSPE was made, the patient remained in home hospice care until his death. Investigators from the Oregon Health Authority and the Oregon Health and Science University reviewed the patients medical records and interviewed the parents. Vaccination against measles can prevent not only acute measles and its complications, but also SSPE.

Do Pertussis Vaccines Protect Against Bordetella parapertussis

We calculated the effectiveness of pertussis vaccine in preventing parapertussis among Oregon children 2 months to 10 years of age using 2 methods. During 2011-2016, the 2 VE methods found 66% (95% CI, 59-75%) and 82% (95% CI, 69-90%) effectiveness against parapertussis. Pertussis vaccine may induce cross-immunity.

Differences in Pertussis Incidence by Income among Oregon Teens during an Outbreak

That disease and poverty are connected is a cornerstone of public health thought. In the case of pertussis, however, it is possible that the expected relationship to poverty is reversed. Grounds exist for considering that increases in income are associated with increases in pertussis rates, both in terms of real risk through social and network features and through the possibility of greater likelihood of care seeking and detection based on income. Using reported adolescent pertussis cases from a 2012 outbreak in Oregon, pertussis incidence rates were determined for areas grouped by zip code into higher, middle, and lower median household income. Adolescents of ages 13–16 years in higher income areas were 2.6 times (95% CI 1.8–3.8) more likely as all others to have reported pertussis during the 2012 outbreak and 3.1 (95% CI 1.4–6.5) times as likely as those in lower income areas. The higher pertussis rates associated with higher income areas were observed regardless of Tdap rate differences. These results suggest that income may be associated with disease risk, likelihood of diagnosis and reporting, or both. Further evaluation of this finding is warranted.

Suffer the Infants: A Severe Case of Pertussis in Oregon, 2012.

Pertussis remains a public health concern in Oregon, especially among young infants. The disease can be severe in this age group and is associated with a high inpatient cost. This report describes an Oregon infant who was hospitalized with pertussis for 90 days, required extracorporeal oxygenation for 43 days, suffered complications including stroke, and had hospital charges totaling