Assessing the Impact of the 2020 Council of State and Territorial Epidemiologists Case Definition for Pertussis on Reported Pertussis Cases

BACKGROUND

In 2020, the Council of State and Territorial Epidemiologists (CSTE) pertussis case definition was modified; the main change was classifying PCR-positive cases as confirmed, regardless of cough duration. Pertussis data reported through Enhanced Pertussis Surveillance (EPS) in seven sites and the National Notifiable Diseases Surveillance System (NNDSS) were used to evaluate the impact of the new case definition.

METHODS

We compared the number of EPS cases with cough onset in 2020 to the number that would have been reported based on the prior (2014) CSTE case definition. To assess the impact of the change nationally, the proportion of EPS cases newly reportable under the 2020 CSTE case definition was applied to 2020 NNDSS data to estimate how many additional cases were captured nationally.

RESULTS

Among 442 confirmed and probable cases reported to EPS states in 2020, 42 (9.5%) were newly reportable according to the 2020 case definition. Applying this proportion to the 6,124 confirmed and probable cases reported nationally in 2020, we estimated that the new definition added 582 cases. Had the case definition not changed, reported cases in 2020 would have decreased by 70% from 2019; the observed decrease was 67%.

CONCLUSIONS

Despite a substantial decrease in reported pertussis cases in the setting of COVID-19, our data show that the 2020 pertussis case definition change resulted in additional case reporting compared with the previous case definition, providing greater opportunities for public health interventions such as prophylaxis of close contacts.

Differences in Pertussis Incidence by Race and Ethnicity in the United States, 2010-2017

Background

An increased pertussis burden has been demonstrated among Hispanic or Latino and American Indian or Alaska Native (AI/AN) infants. However, data on potential disparities among other age and racial groups are limited.

Methods

We analyzed pertussis cases reported through Enhanced Pertussis Surveillance from 2010 to 2017. Pertussis and severe pertussis incidence were calculated by race (White, Black or African American, AI/AN, and Asian or Pacific Islanders), ethnicity (Hispanic or Latino and non-Hispanic or non-Latino), and age.

Results

Compared with White persons, overall incidence was lower among Black or African American (incidence rate ratio [IRR], .57; 95% confidence interval [CI], .53-.61), AI/AN (IRR, 0.65; 95% CI, .58-.72), and Asian or Pacific Islander persons (IRR, 0.39; 95% CI, .35-.43). Overall incidence of pertussis was higher (1.5-fold; 95% CI, 1.37-1.60) among Hispanic or Latino compared with non-Hispanic or non-Latino adults, potentially related to household size or lower pertussis vaccine uptake among adult Hispanic or Latino cases. Severe pertussis incidence was similar among Black or African American and AI/AN persons compared with White persons. Among infants, severe pertussis incidence was 1.4-fold higher (95% CI, 1.03-1.82) among Black or African American infants than among White infants, and 2.1-fold higher (95% CI, 1.67-2.57) among Hispanic or Latino infants than non-Hispanic or non-Latino infants.

Conclusions

The contrast between lower reported incidence but similar or higher severe pertussis incidence among Black or African American and AI/AN persons compared with White persons warrants further investigation and may reflect underdiagnosis or underreporting of mild disease.

Evaluation of Asymptomatic Bordetella Carriage in a Convenience Sample of Children and Adolescents in Atlanta, Georgia, United States

Few data exist on asymptomatic carriage of Bordetella species among populations receiving acellular pertussis vaccine. We conducted a cross-sectional study among acellular-vaccinated children presenting to an emergency department (ED). Bordetella pertussis carriage prevalence was <1% in this population, a lower prevalence than that found in recent studies among whole-cell pertussis-vaccinated participants.

Influenza, Tdap, and COVID-19 Vaccination Coverage and Hesitancy Among Pregnant Women - United States, April 2023

Influenza, tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap), and COVID-19 vaccines can reduce the risk for influenza, pertussis, and COVID-19 among pregnant women and their infants. To assess influenza, Tdap, and COVID-19 vaccination coverage among women pregnant during the 2022-23 influenza season, CDC analyzed data from an Internet panel survey conducted during March 28-April 16, 2023. Among 1,814 survey respondents who were pregnant at any time during October 2022-January 2023, 47.2% reported receiving influenza vaccine before or during their pregnancy. Among 776 respondents with a live birth by their survey date, 55.4% reported receiving Tdap vaccine during pregnancy. Among 1,252 women pregnant at the time of the survey, 27.3% reported receipt of a COVID-19 bivalent booster dose before or during the current pregnancy. Data from the same questions included in surveys conducted during influenza seasons 2019-20 through 2022-23 show that the proportion of pregnant women who reported being very hesitant about influenza and Tdap vaccinations during pregnancy increased from 2019-20 to 2022-23. Pregnant women who received a provider recommendation for vaccination were less hesitant about influenza and Tdap vaccines. Promotion of efforts to improve vaccination coverage among pregnant women, such as provider recommendation for vaccination and informative conversations with patients to address vaccine hesitancy, might reduce vaccine hesitancy and increase coverage with these important vaccines to protect mothers and their infants against severe respiratory diseases.

US Infant Pertussis Incidence Trends Before and After Implementation of the Maternal Tetanus, Diphtheria, and Pertussis Vaccine

Importance

Infants younger than 1 year have the highest burden of pertussis morbidity and mortality. In 2011, the US introduced tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccination during pregnancy to protect infants before vaccinations begin.

Objective

To assess the association of maternal Tdap vaccination during pregnancy with the incidence of pertussis among infants in the US.

Design, Setting, and Participants

In this ecologic study, a time-trend analysis was performed of infant pertussis cases reported through the National Notifiable Diseases Surveillance System between January 1, 2000, and December 31, 2019, in the US. Statistical analysis was performed from April 1, 2020, to October 31, 2022.

Exposures

Maternal Tdap vaccination during pregnancy.

Main Outcomes and Measures

Pertussis incidence rates were calculated and compared between 2 periods-the pre-maternal Tdap vaccination period (2000-2010) and the post-maternal Tdap vaccination period (2012-2019)-for 2 age groups: infants younger than 2 months (target group of maternal vaccination) and infants aged 6 months to less than 12 months (comparison group). Incidence rate differences between the 2 age groups were modeled using weighted segmented linear regression. The slope difference between the 2 periods was estimated to assess the association of maternal Tdap vaccination with pertussis incidence among infants.

Results

A total of 57 460 pertussis cases were reported in infants younger than 1 year between 2000 and 2019; 19 322 cases (33.6%) were in infants younger than 2 months. During the pre-maternal Tdap vaccination period, annual pertussis incidence did not change among infants younger than 2 months (slope, 3.29 per 100 000 infants per year; P = .28) but increased slightly among infants aged 6 months to less than 12 months (slope, 2.10 per 100 000 infants per year; P = .01). There was no change in the difference in incidence between the 2 age groups (slope, 0.08 per 100 000 infants per year; P = .97) during the pre-maternal Tdap vaccination period overall. However, in the post-maternal Tdap vaccination period, incidence decreased among infants younger than 2 months (slope, -14.53 per 100 000 infants per year; P = .001) while remaining unchanged among infants aged 6 months to less than 12 months (slope, 1.42 per 100 000 infants per year; P = .29). The incidence rate difference between the 2 age groups significantly decreased during the post-maternal Tdap vaccination period (slope, -14.43 per 100 000 infants per year; P < .001). Pertussis incidence rate differences were significantly different between the pre-maternal and post-maternal Tdap vaccination periods (slope difference, -14.51 per 100 000 infants per year; P = .01).

Conclusions and Relevance

In this study, following maternal Tdap vaccine introduction, a sustained decrease in pertussis incidence was observed among infants younger than 2 months, narrowing the incidence gap with infants aged 6 months to less than 12 months. These findings suggest that maternal Tdap vaccination is associated with a reduction in pertussis burden in the target age group (<2 months) and that further increases in coverage may be associated with additional reductions in infant disease.

Tetanus, Diphtheria, and Acellular Pertussis Vaccination Coverage Among Publicly Insured Pregnant Women, U.S., 2016-2019

Introduction

Vaccination with tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis vaccine during pregnancy is highly effective against Bordetella pertussis in young infants. We aimed to evaluate the uptake of maternal tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis vaccination during the recommended gestation period of 27 through 36 weeks among women enrolled in a public medical insurance plan in the U.S.

Methods

In this analysis using Centers for Medicare and Medicaid Services insurance claims data, we identified women aged 15 through 49 years who delivered a live-born infant from 2016 through 2019. We identified claims for tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis vaccination to calculate the proportion of women who were vaccinated during Weeks 27 through 36 of gestation in each calendar year. We also assessed the average annual maternal tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis coverage by age group, race and ethnicity, U.S. Census region of residence, and plan type. Data were analyzed in 2021.

Results

Among 4,318,823 deliveries, the 4-year national average for tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis vaccination was 26%, improving from 22% in 2016 to 31% in 2019 (p<0.001). Within subgroups, the lowest 4-year average coverage was among women aged 15 through 18 years (22%); Black, non-Hispanic (23%) and Hispanic women (24%); those residing in the South (18%); those enrolled in a Children's Health Insurance Program plan (22%); and those covered by a fee-for-service plan (19%). Coverage increased across all subgroups from 2016 through 2019.

Conclusions

Although maternal tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis coverage among publicly insured women in the U.S. increased from 2016 through 2019, it remained considerably lower than estimated national coverage, with notable differences by race and ethnicity.

Maternal Tetanus Toxoid, Reduced Diphtheria Toxoid, and Acellular Pertussis Vaccination During Pregnancy: Impact on Infant Anti-Pertussis Antibody Concentrations by Maternal Pertussis Priming Series

BACKGROUND

Acellular pertussis (aP) vaccines replaced whole-cell pertussis (wP) vaccines for the US childhood primary series in 1997. As women primed with aP vaccines enter childbearing age, protection of infants through tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccination during pregnancy may be impacted.

METHODS

Term infants born to women vaccinated with Tdap during pregnancy were included. Geometric mean concentrations (GMCs) of pertussis-specific immunoglobulin G antibodies (international units per milliliter) in cord blood of infants born to women born after 1997 (aP-primed) were compared with those born to women born before 1992 (wP-primed).

RESULTS

253 and 506 infants born to aP- and wP-primed women, respectively, were included. Compared with wP-primed women, aP-primed women were younger, more likely to be Hispanic or non-Hispanic Black, and had lower-birthweight infants (P < .01 for all). Antibodies against pertussis toxin (PT) and filamentous hemagglutinin (FHA) were lower among infants born to aP-primed vs wP-primed women (PT, 17.3 vs 36.4; GMC ratio, .475; 95% confidence interval [CI], .408-.552 and FHA, 104.6 vs 121.4; GMC ratio, 0.861; 95% CI, .776-.958). No differences were observed for anti-fimbriae or anti-pertactin antibodies.

CONCLUSIONS

Transplacental anti-pertussis antibody concentrations in infants of women vaccinated with Tdap during pregnancy differed by type of childhood vaccine the women received. Notably, anti-PT antibody levels, considered most important in preventing severe infant disease, were lower in infants born to aP-primed vs wP-primed women. Maternal Tdap vaccination may confer less protection against pertussis in infants born to aP-primed vs those born to wP-primed women.

High post-exposure prophylaxis (PEP) uptake among household contacts of pertussis patients enrolled in a PEP effectiveness evaluation - United States, 2015-2017

BACKGROUND

Post-exposure prophylaxis (PEP) for pertussis is recommended for household contacts of pertussis cases in the United States within 21 days of exposure, but data on PEP effectiveness for prevention of secondary cases in the setting of widespread pertussis vaccination are limited. We implemented a multi-state evaluation of azithromycin PEP use and effectiveness among household contacts.

METHODS

Culture- or PCR-confirmed pertussis cases were identified through surveillance. Household contacts were interviewed within 7 days of case report and again 14-21 days later. Interviewers collected information on exposure, demographics, vaccine history, prior pertussis diagnosis, underlying conditions, PEP receipt, pertussis symptoms, and pertussis testing. A subset of household contacts provided nasopharyngeal and blood specimens during interviews.

RESULTS

Of 299 household contacts who completed both interviews, 12 (4%) reported not receiving PEP. There was no evidence of higher prevalence of cough or pertussis symptoms among contacts who did not receive PEP. Of 168 household contacts who provided at least one nasopharyngeal specimen, four (2.4%) were culture or PCR positive for B. pertussis; three of these received PEP prior to their positive test result. Of 156 contacts with serologic results, 14 (9%) had blood specimens that were positive for IgG anti-pertussis toxin (PT) antibodies; all had received PEP.

CONCLUSIONS

Very high PEP uptake was observed among household contacts of pertussis patients. Although the number of contacts who did not receive PEP was small, there was no difference in prevalence of pertussis symptoms or positive laboratory results among these contacts compared with those who did receive PEP.

Maternal Vaccination in Argentina: Tetanus, Diphtheria, and Acellular Pertussis Vaccine Effectiveness During Pregnancy in Preventing Pertussis in Infants <2 Months of Age

BACKGROUND

In 2011, Argentina experienced its highest pertussis incidence and mortality rates of the last decade; 60% of deaths were among infants aged <2 months. In response, a dose of tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccine was recommended for all pregnant women at ≥20 weeks of gestation. Although recent studies suggest that maternal Tdap vaccination is effective at preventing infant disease, no data have come from low- or middle-income countries, nor from ones using whole-cell pertussis vaccines for primary immunization.

METHODS

We conducted a matched case-control evaluation to assess the effectiveness of maternal Tdap vaccination in preventing pertussis among infants aged <2 months in Argentina. Pertussis case patients identified from September 2012 to March 2016 at 6 hospital sites and confirmed by polymerase chain reaction testing were included. Five randomly selected controls were matched to each case patient by hospital site and mother's health district. We used multivariable conditional logistic regression to calculate odds ratios (ORs). Vaccine effectiveness (VE) was estimated as (1 - OR) × 100%.

RESULTS

Seventy-one case patients and 300 controls were included in the analysis. Forty-nine percent of case patients and 78% of controls had mothers who were vaccinated during pregnancy. Overall Tdap VE was estimated at 80.7% (95% confidence interval, 52.1%-92.2%). We found similar VE whether Tdap was administered during the second or third trimester.

CONCLUSIONS

Tdap vaccination during pregnancy is effective in preventing pertussis in infants aged <2 months in Argentina, with similar effectiveness whether administered during the second or third trimester of pregnancy.

Pertussis Infections Among Pregnant Women in the United States, 2012–2017

Background

Little is known about pertussis among pregnant women, a population at increased risk for severe morbidity from respiratory infections such as influenza. We used the Centers for Disease Control and Prevention’s Enhanced Pertussis Surveillance (EPS) system to describe pertussis epidemiology among pregnant and nonpregnant women of childbearing age.

Methods

Pertussis cases in women aged 18–44 years with cough onset between 1 January 2012 and 31 December 2017 were identified in 7 EPS states. Surveillance data were collected through patient and provider interviews and immunization registries. Bridged-race, intercensal population data and live birth estimates were used as denominators.

Results

We identified 1582 pertussis cases among women aged 18–44 years; 5.1% (76/1499) of patients with a known pregnancy status were pregnant at cough onset. Of the pregnant patients with complete information, 81.7% (49/60) reported onset during the second or third trimester. The median ages of pregnant and nonpregnant patients were 29.0 and 33.0 years, respectively. Most pregnant and nonpregnant patients were White (78.3% vs. 86.4%, respectively; P = .09) and non-Hispanic (72.6% vs. 77.3%, respectively; P = .35). The average annual incidence of pertussis was 7.7/100000 among pregnancy women and 7/3/100000 among nonpregnant women. Compared to nonpregnant patients, more pregnant patients reported whoop (41.9% vs. 31.3%, respectively), posttussive vomiting (58.1% vs. 47.9%, respectively), and apnea (37.3% vs. 29.0%, respectively); however, these differences were not statistically significant (P values &gt; .05 for all). A similar proportion of pregnant and nonpregnant patients reported ever having received Tdap (tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis vaccine; 31.6% vs. 32.7%, respectively; P = .84).

Conclusions

Our analysis suggests that incidence of pertussis and clinical characteristics of disease are similar among pregnant and nonpregnant women. Continued monitoring is important to further define pertussis epidemiology in pregnant women.

Severe Pertussis Infections in the United States, 2011-2015

Background

The incidence of pertussis in the United States has increased in recent years. While characteristics of severe pertussis infection have been described in infants, fewer data are available in older children and adults. In this analysis, we characterize pertussis infections in hospitalized patients of all ages.

Methods

Cases of pertussis with cough onset from 1 January 2011 through 31 December 2015 from 7 US Emerging Infections Program Network states were reviewed. Additional information on hospitalized patients was obtained through abstraction of the inpatient medical record. Descriptive and multivariable analyses were conducted to characterize severe pertussis infection and identify potential risk factors.

Results

Among 15942 cases of pertussis reported, 515 (3.2%) were hospitalized. Three hospitalized patients died. Infants aged <2 months accounted for 1.6% of all pertussis cases but 29.3% of hospitalizations. Infants aged 2–11 months and adults aged ≥65 years also had high rates of hospitalization. Infants aged <2 months whose mothers received acellular pertussis during the third trimester and children aged 2 months to 11 years who were up to date on pertussis-containing vaccines had a 43%–66% reduced risk of hospitalization. Among adolescents aged 12–20 years, 43.5% had a history of asthma, and among adults aged ≥65 years, 26.8% had a history of chronic obstructive pulmonary disease.

Conclusions

Individuals at the extreme ends of life may be the most vulnerable to severe pertussis infections, though hospitalization was reported across all age groups. Continued monitoring of severe pertussis infections will be important to help guide prevention, control, and treatment options.

Vital Signs: Burden and Prevention of Influenza and Pertussis Among Pregnant Women and Infants - United States

Introduction

Vaccinating pregnant women with influenza vaccine and tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis vaccine (Tdap) can reduce influenza and pertussis risk for themselves and their infants.

Methods

Surveillance data were analyzed to ascertain influenza-associated hospitalization among pregnant women and infant hospitalization and death associated with influenza and pertussis. An Internet panel survey was conducted during March 27–April 8, 2019, among women aged 18–49 years who reported being pregnant any time since August 1, 2018. Influenza vaccination before or during pregnancy was assessed among respondents with known influenza vaccination status who were pregnant any time during October 2018–January 2019 (2,097). Tdap receipt during pregnancy was assessed among respondents with known Tdap status who reported a live birth by their survey date (817).

Results

From 2010–11 to 2017–18, pregnant women accounted for 24%–34% of influenza-associated hospitalizations per season among females aged 15–44 years. From 2010 to 2017, a total of 3,928 pertussis-related hospitalizations were reported among infants aged <2 months (annual range = 262–743). Maternal influenza and Tdap vaccination coverage rates reported as of April 2019 were 53.7% and 54.9%, respectively. Among women whose health care providers offered vaccination or provided referrals, 65.7% received influenza vaccine and 70.5% received Tdap. The most commonly reported reasons for nonvaccination were believing the vaccine is not effective (influenza; 17.6%) and not knowing that vaccination is needed during each pregnancy (Tdap; 37.9%), followed by safety concerns for the infant (influenza =15.9%; Tdap = 17.1%).

Conclusions and Implications for Public Health Practice

Many pregnant women do not receive the vaccines recommended to protect themselves and their infants, even when vaccination is offered. CDC and provider organizations’ resources are available to help providers convey strong, specific recommendations for influenza and Tdap vaccination that are responsive to pregnant women’s concerns.

An Assessment of the Cocooning Strategy for Preventing Infant Pertussis-United States, 2011

BACKGROUND

 Infants are at greatest risk for severe pertussis. In 2006, the Advisory Committee on Immunization Practices recommended that adolescents and adults, especially those with infant contact, receive a single dose of Tdap (tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis vaccine). To assess the effectiveness of cocooning, we conducted a case-control evaluation of infant close contacts.

METHODS

 Pertussis cases aged <2 months with onset between 1 January 2011 and 31 December 2011 were identified in Emerging Infections Program Network sites. For each case, we recruited 3 controls from birth certificates and interviewed identified adult close contacts (CCs) or parents of CCs aged <18 years. Pertussis vaccination was verified through medical providers and/or immunization registries.

RESULTS

 Forty-two cases were enrolled, with 154 matched controls. Around enrolled infants, 859 CCs were identified (600 adult and 259 nonadult). An average of 5.4 CCs was identified per case and 4.1 CCs per control. Five hundred fifty-four (64.5%) CCs were enrolled (371 adult and 183 non-adult CCs); 119 (32.1% of enrolled) adult CCs had received Tdap. The proportion of Tdap-vaccinated adult CCs was similar between cases and controls (P = .89). The 600 identified adult CCs comprised 172 potential cocoons; 71 (41.3%) potential cocoons had all identified adult CCs enrolled. Of these, 9 were fully vaccinated and 43.7% contained no Tdap-vaccinated adults. The proportion of fully vaccinated case (4.8%) and control (10.0%) cocoons was similar (P = .43).

CONCLUSIONS

 Low Tdap coverage among adult CCs reinforces the difficulty of implementing the cocooning strategy and the importance of vaccination during pregnancy to prevent infant pertussis.

Impact of the US Maternal Tetanus, Diphtheria, and Acellular Pertussis Vaccination Program on Preventing Pertussis in Infants <2 Months of Age: A Case-Control Evaluation

BACKGROUND

Infants aged <1 year are at highest risk for pertussis-related morbidity and mortality. In 2012, Tdap (tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis) vaccine was recommended for women during each pregnancy to protect infants in the first months of life; data on effectiveness of this strategy are currently limited.

METHODS

We conducted a case-control evaluation among pertussis cases <2 months old with cough onset between 1 January 2011 and 31 December 2014 from 6 US Emerging Infection Program Network states. Controls were hospital-matched and selected by birth certificate. Mothers were interviewed to collect information on demographics, household characteristics, and healthcare providers. Provider-verified immunization history was obtained on mothers and infants. Mothers were considered vaccinated during pregnancy if Tdap was received ≥14 days before delivery; trimester was calculated using Tdap date, infant's date of birth, and gestational age. Odds ratios were calculated using multivariable conditional logistic regression; vaccine effectiveness (VE) was estimated as (1 - odds ratio) × 100%.

RESULTS

A total of 240 cases and 535 controls were included; 17 (7.1%) case mothers and 90 (16.8%) control mothers received Tdap during the third trimester of pregnancy. The multivariable VE estimate for Tdap administered during the third trimester of pregnancy was 77.7% (95% confidence interval [CI], 48.3%-90.4%); VE increased to 90.5% (95% CI, 65.2%-97.4%) against hospitalized cases.

CONCLUSIONS

Vaccination during pregnancy is an effective way to protect infants during the early months of life. With a continuing resurgence in pertussis, efforts should focus on maximizing Tdap uptake among pregnant women.

Surveillance of Vaccination Coverage among Adult Populations - United States, 2015

PROBLEM/CONDITION

Overall, the prevalence of illness attributable to vaccine-preventable diseases is greater among adults than among children. Adults are recommended to receive vaccinations based on their age, underlying medical conditions, lifestyle, prior vaccinations, and other considerations. Updated vaccination recommendations from CDC are published annually in the U.S. Adult Immunization Schedule. Despite longstanding recommendations for use of many vaccines, vaccination coverage among U.S. adults is low.

PERIOD COVERED

August 2014-June 2015 (for influenza vaccination) and January-December 2015 (for pneumococcal, tetanus and diphtheria [Td] and tetanus and diphtheria with acellular pertussis [Tdap], hepatitis A, hepatitis B, herpes zoster, and human papillomavirus [HPV] vaccination).

DESCRIPTION OF SYSTEM

The National Health Interview Survey (NHIS) is a continuous, cross-sectional national household survey of the noninstitutionalized U.S. civilian population. In-person interviews are conducted throughout the year in a probability sample of households, and NHIS data are compiled and released annually. The survey objective is to monitor the health of the U.S. population and provide estimates of health indicators, health care use and access, and health-related behaviors.

RESULTS

Compared with data from the 2014 NHIS, increases in vaccination coverage occurred for influenza vaccine among adults aged ≥19 years (a 1.6 percentage point increase compared with the 2013-14 season to 44.8%), pneumococcal vaccine among adults aged 19-64 years at increased risk for pneumococcal disease (a 2.8 percentage point increase to 23.0%), Tdap vaccine among adults aged ≥19 years and adults aged 19-64 years (a 3.1 percentage point and 3.3 percentage point increase to 23.1% and to 24.7%, respectively), herpes zoster vaccine among adults aged ≥60 years and adults aged ≥65 years (a 2.7 percentage point and 3.2 percentage point increase to 30.6% and to 34.2%, respectively), and hepatitis B vaccine among health care personnel (HCP) aged ≥19 years (a 4.1 percentage point increase to 64.7%). Herpes zoster vaccination coverage in 2015 met the Healthy People 2020 target of 30%. Aside from these modest improvements, vaccination coverage among adults in 2015 was similar to estimates from 2014. Racial/ethnic differences in coverage persisted for all seven vaccines, with higher coverage generally for whites compared with most other groups. Adults without health insurance reported receipt of influenza vaccine (all age groups), pneumococcal vaccine (adults aged 19-64 years at increased risk), Td vaccine (adults aged ≥19 years, 19-64 years, and 50-64 years), Tdap vaccine (adults aged ≥19 years and 19-64 years), hepatitis A vaccine (adults aged ≥19 years overall and among travelers), hepatitis B vaccine (adults aged ≥19 years, 19-49 years, and among travelers), herpes zoster vaccine (adults aged ≥60 years), and HPV vaccine (males and females aged 19-26 years) less often than those with health insurance. Adults who reported having a usual place for health care generally reported receipt of recommended vaccinations more often than those who did not have such a place, regardless of whether they had health insurance. Vaccination coverage was higher among adults reporting one or more physician contacts in the past year compared with those who had not visited a physician in the past year, regardless of whether they had health insurance. Even among adults who had health insurance and ≥10 physician contacts within the past year, depending on the vaccine, 18.2%-85.6% reported not having received vaccinations that were recommended either for all persons or for those with specific indications. Overall, vaccination coverage among U.S.-born adults was higher than that among foreign-born adults, with few exceptions (influenza vaccination [adults aged 19-49 years and 50-64 years], hepatitis A vaccination [adults aged ≥19 years], and hepatitis B vaccination [adults aged ≥19 years with diabetes or chronic liver conditions]).

INTERPRETATION

Coverage for all vaccines for adults remained low but modest gains occurred in vaccination coverage for influenza (adults aged ≥19 years), pneumococcal (adults aged 19-64 years with increased risk), Tdap (adults aged ≥19 years and adults aged 19-64 years), herpes zoster (adults aged ≥60 years and ≥65 years), and hepatitis B (HCP aged ≥19 years); coverage for other vaccines and groups with vaccination indications did not improve. The 30% Healthy People 2020 target for herpes zoster vaccination was met. Racial/ethnic disparities persisted for routinely recommended adult vaccines. Missed opportunities to vaccinate remained. Although having health insurance coverage and a usual place for health care were associated with higher vaccination coverage, these factors alone were not associated with optimal adult vaccination coverage. HPV vaccination coverage for males and females has increased since CDC recommended vaccination to prevent cancers caused by HPV, but many adolescents and young adults remained unvaccinated.

PUBLIC HEALTH ACTIONS

Assessing factors associated with low coverage rates and disparities in vaccination is important for implementing strategies to improve vaccination coverage. Evidence-based practices that have been demonstrated to improve vaccination coverage should be used. These practices include assessment of patients' vaccination indications by health care providers and routine recommendation and offer of needed vaccines to adults, implementation of reminder-recall systems, use of standing-order programs for vaccination, and assessment of practice-level vaccination rates with feedback to staff members. For vaccination coverage to be improved among those who reported lower coverage rates of recommended adult vaccines, efforts also are needed to identify adults who do not have a regular provider or insurance and who report fewer health care visits.

Changes in Predominance of Pulsed-Field Gel Electrophoresis Profiles of Bordetella pertussis Isolates, United States, 2000-2012

These changes are concurrrent with other recent molecular changes and may be contributing to US pertussis reemergence.

To clarify the characteristics of circulating Bordetella pertussis isolates, we used pulsed-field gel electrophoresis (PFGE) to analyze 5,262 isolates collected in the United States during 2000–2012. We found 199 PFGE profiles; 5 profiles accounted for 72% of isolates. The most common profile, CDC013, accounted for 35%–46% of isolates tested from 2000–2009; however, the proportion of isolates of this profile rapidly decreased in 2010. Profile CDC237, first seen in 2009, increased rapidly and accounted for 29% of 2012 isolates. No location bias was observed among profiles during 2000–2010, but differences were observed among isolates from different states during 2012. Predominant profiles match those observed in recent European PFGE studies. PFGE profile changes are concurrent with other recent molecular changes in B. pertussis and may be contributing to the reemergence of pertussis in the United States. Continued PFGE monitoring is critical for understanding the changing epidemiology of pertussis.

Bordetella pertussis Strain Lacking Pertactin and Pertussis Toxin

A Bordetella pertussis strain lacking 2 acellular vaccine immunogens, pertussis toxin and pertactin, was isolated from an unvaccinated infant in New York State in 2013. Comparison with a French strain that was pertussis toxin–deficient, pertactin wild-type showed that the strains carry the same 28-kb deletion in similar genomes.

Effect of Culture-Independent Diagnostic Tests on Future Emerging Infections Program Surveillance

The Centers for Disease Control and Prevention Emerging Infections Program (EIP) network conducts population-based surveillance for pathogens of public health importance. Central to obtaining estimates of disease burden and tracking microbiological characteristics of these infections is accurate laboratory detection of pathogens. The use of culture-independent diagnostic tests (CIDTs) in clinical settings presents both opportunities and challenges to EIP surveillance. Because CIDTs offer better sensitivity than culture and are relatively easy to perform, their use could potentially improve estimates of disease burden. However, changes in clinical testing practices, use of tests with different sensitivities and specificities, and changes to case definitions make it challenging to monitor trends. Isolates are still needed for performing strain typing, antimicrobial resistance testing, and identifying other molecular characteristics of organisms. In this article, we outline current and future EIP activities to address issues associated with adoption of CIDTs, which may apply to other public health surveillance.

Tracking Pertussis and Evaluating Control Measures through Enhanced Pertussis Surveillance, Emerging Infections Program, United States

Despite high coverage with pertussis-containing vaccines, pertussis remains endemic to the United States. There have been increases in reported cases in recent years, punctuated by striking epidemics and shifting epidemiology, both of which raise questions about current policies regarding its prevention and control. Limited data on pertussis reported through the National Notifiable Disease Surveillance System have proved insufficient to answer these questions. To address shortcomings of national pertussis data, the Emerging Infections Program at the US Centers for Disease Control and Prevention launched Enhanced Pertussis Surveillance (EPS), which is characterized by systematic case ascertainment, augmented data collection, and collection of Bordetella pertussis isolates. Data collected through EPS have been instrumental in understanding the rapidly evolving epidemiology and molecular epidemiology of pertussis and have contributed essential information regarding pertussis vaccines. EPS also serves as a platform for conducting critical and timely evaluations of pertussis prevention and control strategies, including targeting of vaccinations and antimicrobial prophylaxis.

Impact of Tetanus Toxoid, Reduced Diphtheria Toxoid, and Acellular Pertussis Vaccinations on Reported Pertussis Cases Among Those 11 to 18 Years of Age in an Era of Waning Pertussis Immunity: A Follow-up Analysis

IMPORTANCE

There is accumulating literature on waning acellular pertussis vaccine-induced immunity, confirming the results of studies assessing the duration of protection of pertussis vaccines.

OBJECTIVE

To evaluate the tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccine's effect over time among those 11 to 18 years old, while accounting for the transition from whole-cell to acellular pertussis vaccines for the childhood primary series.

DESIGN, SETTING, AND PARTICIPANTS

Extended, retrospective analysis of reported pertussis cases between January 1, 1990, and December 31, 2014, in the United States. The analysis included all nationally reported pertussis cases.

EXPOSURE

US Tdap vaccination program and the transition from whole-cell to acellular pertussis vaccines.

MAIN OUTCOMES AND MEASURES

Rate ratios of reported pertussis incidence (defined as incidence among 11- to 18-year-old individuals divided by the combined incidence in all other age groups) modeled with segmented regression analysis and age-specific trends in reported pertussis incidence over time.

RESULTS

Between 1990 and 2014, 356 557 pertussis cases were reported in the United States. Of those, 191 914 (53.8%) were female and 240 665 (67.5%) were white. Overall incidence increased from 1.7 in 100 000 to 4.0 in 100 000 between 1990 and 2003, while latter years were dominated by epidemic peaks. Incidence was highest among infants younger than 1 year throughout the analysis period. Pertussis rates were comparable among all other age groups until the late 2000s, when an increased burden of pertussis emerged among children 1 to 10 years old, resulting in the second highest age-specific incidence. By 2014, 11- to 18-year-old individuals once again had the second highest incidence. While slope coefficients from segmented regression analysis showed a positive impact of Tdap immediately following introduction (slope, -0.4959; P < .001), a reversal in trends was observed in 2010 when rates of disease among 11- to 18-year-old individuals increased at a faster rate than all other age groups combined (slope, 0.5727; P < .001).

CONCLUSIONS AND RELEVANCE

While the impact of Tdap among adolescents looked promising following vaccine introduction, our extended analysis found that trends in adolescent disease were abruptly reversed in 2010, corresponding directly to the aging of acellular pertussis-vaccinated cohorts. Despite the apparent limitations of Tdap, it remains the best prevention against disease in adolescents.

Surveillance of Vaccination Coverage Among Adult Populations - United States, 2014

PROBLEM/CONDITION

Overall, the prevalence of illness attributable to vaccine-preventable diseases is greater among adults than among children. Adults are recommended to receive vaccinations based on their age, underlying medical conditions, lifestyle, prior vaccinations, and other considerations. Updated vaccination recommendations from CDC are published annually in the U.S. Adult Immunization Schedule. Despite longstanding recommendations for use of many vaccines, vaccination coverage among U.S. adults is low.

REPORTING PERIOD

August 2013-June 2014 (for influenza vaccination) and January-December 2014 (for pneumococcal, tetanus and diphtheria [Td] and tetanus and diphtheria with acellular pertussis [Tdap], hepatitis A, hepatitis B, herpes zoster, and human papillomavirus [HPV] vaccination).

DESCRIPTION OF SYSTEM

The National Health Interview Survey (NHIS) is a continuous, cross-sectional national household survey of the noninstitutionalized U.S. civilian population. In-person interviews are conducted throughout the year in a probability sample of households, and NHIS data are compiled and released annually. The survey objective is to monitor the health of the U.S. population and provide estimates of health indicators, health care use and access, and health-related behaviors.

RESULTS

Compared with data from the 2013 NHIS, increases in vaccination coverage occurred for Tdap vaccine among adults aged ≥19 years (a 2.9 percentage point increase to 20.1%) and herpes zoster vaccine among adults aged ≥60 years (a 3.6 percentage point increase to 27.9%). Aside from these modest improvements, vaccination coverage among adults in 2014 was similar to estimates from 2013 (for influenza coverage, similar to the 2012-13 season). Influenza vaccination coverage among adults aged ≥19 years was 43.2%. Pneumococcal vaccination coverage among high-risk persons aged 19-64 years was 20.3% and among adults aged ≥65 years was 61.3%. Td vaccination coverage among adults aged ≥19 years was 62.2%. Hepatitis A vaccination coverage among adults aged ≥19 years was 9.0%. Hepatitis B vaccination coverage among adults aged ≥19 years was 24.5%. HPV vaccination coverage among adults aged 19-26 years was 40.2% for females and 8.2% for males. Racial/ethnic differences in coverage persisted for all seven vaccines, with higher coverage generally for whites compared with most other groups. Adults without health insurance were significantly less likely than those with health insurance to report receipt of influenza vaccine (aged ≥19 years), pneumococcal vaccine (aged 19-64 years with high-risk conditions and aged ≥65 years), Td vaccine (aged ≥19 years), Tdap vaccine (aged ≥19 years and 19-64 years), hepatitis A vaccine (aged ≥19 years overall and among travelers), hepatitis B vaccine (aged ≥19 years, 19-49 years, and 19-59 years with diabetes), herpes zoster vaccine (aged ≥60 years and 60-64 years), and HPV vaccine (females aged 19-26 years and males aged 19-26 years). Adults who reported having a usual place for health care generally were more likely to receive recommended vaccinations than those who did not have a usual place for health care, regardless of whether they had health insurance. Vaccination coverage was significantly higher among those reporting one or more physician contacts in the past year compared with those who had not visited a physician in the past year, regardless of whether they had health insurance. Even among adults who had health insurance and ≥10 physician contacts within the past year, 23.8%-88.8% reported not having received vaccinations that were recommended either for all persons or for those with some specific indication. Overall, vaccination coverage among U.S.-born respondents was significantly higher than that of foreign-born respondents with few exceptions (influenza vaccination [adults aged 19-49 years], hepatitis A vaccination [adults aged ≥19 years], hepatitis B vaccination [adults with diabetes aged ≥60 years], and HPV vaccination [males aged 19-26 years]).

INTERPRETATION

Overall, increases in adult vaccination coverage are needed. Although modest gains occurred in Tdap vaccination coverage among adults aged ≥19 years and herpes zoster vaccination coverage among adults aged ≥60 years, coverage for other vaccines and risk groups did not improve, and racial/ethnic disparities persisted for routinely recommended adult vaccines. Coverage for all vaccines for adults remained low, and missed opportunities to vaccinate adults continued. Although having health insurance coverage and a usual place for health care are associated with higher vaccination coverage, these factors alone do not assure optimal adult vaccination coverage.

PUBLIC HEALTH ACTIONS

Assessing associations with vaccination is important for understanding factors that contribute to low coverage rates and to disparities in vaccination, and for implementing strategies to improve vaccination coverage. Practices that have been demonstrated to improve vaccination coverage should be used. These practices include assessment of patients' vaccination indications by health care providers and routine recommendation and offer of needed vaccines to adults, implementation of reminder-recall systems, use of standing-order programs for vaccination, and assessment of practice-level vaccination rates with feedback to staff members. For vaccination to be improved among those least likely to be up-to-date on recommended adult vaccines, efforts also are needed to identify adults who do not have a regular provider or insurance and who report fewer health care visits.

Surveillance of Vaccination Coverage Among Adult Populations - United States, 2014

PROBLEM/CONDITION

Overall, the prevalence of illness attributable to vaccine-preventable diseases is greater among adults than among children. Adults are recommended to receive vaccinations based on their age, underlying medical conditions, lifestyle, prior vaccinations, and other considerations. Updated vaccination recommendations from CDC are published annually in the U.S. Adult Immunization Schedule. Despite longstanding recommendations for use of many vaccines, vaccination coverage among U.S. adults is low.

REPORTING PERIOD

August 2013-June 2014 (for influenza vaccination) and January-December 2014 (for pneumococcal, tetanus and diphtheria [Td] and tetanus and diphtheria with acellular pertussis [Tdap], hepatitis A, hepatitis B, herpes zoster, and human papillomavirus [HPV] vaccination).

DESCRIPTION OF SYSTEM

The National Health Interview Survey (NHIS) is a continuous, cross-sectional national household survey of the noninstitutionalized U.S. civilian population. In-person interviews are conducted throughout the year in a probability sample of households, and NHIS data are compiled and released annually. The survey objective is to monitor the health of the U.S. population and provide estimates of health indicators, health care use and access, and health-related behaviors.

RESULTS

Compared with data from the 2013 NHIS, increases in vaccination coverage occurred for Tdap vaccine among adults aged ≥19 years (a 2.9 percentage point increase to 20.1%) and herpes zoster vaccine among adults aged ≥60 years (a 3.6 percentage point increase to 27.9%). Aside from these modest improvements, vaccination coverage among adults in 2014 was similar to estimates from 2013 (for influenza coverage, similar to the 2012-13 season). Influenza vaccination coverage among adults aged ≥19 years was 43.2%. Pneumococcal vaccination coverage among high-risk persons aged 19-64 years was 20.3% and among adults aged ≥65 years was 61.3%. Td vaccination coverage among adults aged ≥19 years was 62.2%. Hepatitis A vaccination coverage among adults aged ≥19 years was 9.0%. Hepatitis B vaccination coverage among adults aged ≥19 years was 24.5%. HPV vaccination coverage among adults aged 19-26 years was 40.2% for females and 8.2% for males. Racial/ethnic differences in coverage persisted for all seven vaccines, with higher coverage generally for whites compared with most other groups. Adults without health insurance were significantly less likely than those with health insurance to report receipt of influenza vaccine (aged ≥19 years), pneumococcal vaccine (aged 19-64 years with high-risk conditions and aged ≥65 years), Td vaccine (aged ≥19 years), Tdap vaccine (aged ≥19 years and 19-64 years), hepatitis A vaccine (aged ≥19 years overall and among travelers), hepatitis B vaccine (aged ≥19 years, 19-49 years, and 19-59 years with diabetes), herpes zoster vaccine (aged ≥60 years and 60-64 years), and HPV vaccine (females aged 19-26 years and males aged 19-26 years). Adults who reported having a usual place for health care generally were more likely to receive recommended vaccinations than those who did not have a usual place for health care, regardless of whether they had health insurance. Vaccination coverage was significantly higher among those reporting one or more physician contacts in the past year compared with those who had not visited a physician in the past year, regardless of whether they had health insurance. Even among adults who had health insurance and ≥10 physician contacts within the past year, 23.8%-88.8% reported not having received vaccinations that were recommended either for all persons or for those with some specific indication. Overall, vaccination coverage among U.S.-born respondents was significantly higher than that of foreign-born respondents with few exceptions (influenza vaccination [adults aged 19-49 years], hepatitis A vaccination [adults aged ≥19 years], hepatitis B vaccination [adults with diabetes aged ≥60 years], and HPV vaccination [males aged 19-26 years]).

INTERPRETATION

Overall, increases in adult vaccination coverage are needed. Although modest gains occurred in Tdap vaccination coverage among adults aged ≥19 years and herpes zoster vaccination coverage among adults aged ≥60 years, coverage for other vaccines and risk groups did not improve, and racial/ethnic disparities persisted for routinely recommended adult vaccines. Coverage for all vaccines for adults remained low, and missed opportunities to vaccinate adults continued. Although having health insurance coverage and a usual place for health care are associated with higher vaccination coverage, these factors alone do not assure optimal adult vaccination coverage.

PUBLIC HEALTH ACTIONS

Assessing associations with vaccination is important for understanding factors that contribute to low coverage rates and to disparities in vaccination, and for implementing strategies to improve vaccination coverage. Practices that have been demonstrated to improve vaccination coverage should be used. These practices include assessment of patients' vaccination indications by health care providers and routine recommendation and offer of needed vaccines to adults, implementation of reminder-recall systems, use of standing-order programs for vaccination, and assessment of practice-level vaccination rates with feedback to staff members. For vaccination to be improved among those least likely to be up-to-date on recommended adult vaccines, efforts also are needed to identify adults who do not have a regular provider or insurance and who report fewer health care visits.

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.

Twenty Years of Active Bacterial Core Surveillance

Active Bacterial Core surveillance (ABCs) was established in 1995 as part of the Centers for Disease Control and Prevention Emerging Infections Program (EIP) network to assess the extent of invasive bacterial infections of public health importance. ABCs is distinctive among surveillance systems because of its large, population-based, geographically diverse catchment area; active laboratory-based identification of cases to ensure complete case capture; detailed collection of epidemiologic information paired with laboratory isolates; infrastructure that allows for more in-depth investigations; and sustained commitment of public health, academic, and clinical partners to maintain the system. ABCs has directly affected public health policies and practices through the development and evaluation of vaccines and other prevention strategies, the monitoring of antimicrobial drug resistance, and the response to public health emergencies and other emerging infections.

Pertactin-negative Bordetella pertussis strains: evidence for a possible selective advantage

BACKGROUND

A recent increase in Bordetella pertussis without the pertactin protein, an acellular vaccine immunogen, has been reported in the United States. Determining whether pertactin-deficient (PRN(-)) B. pertussis is evading vaccine-induced immunity or altering the severity of illness is needed.

METHODS

We retrospectively assessed for associations between pertactin production and both clinical presentation and vaccine history. Cases with isolates collected between May 2011 and February 2013 from 8 states were included. We calculated unadjusted and adjusted odds ratios (ORs) using multivariable logistic regression analysis.

RESULTS

Among 753 isolates, 640 (85%) were PRN(-). The age distribution differed between cases caused by PRN(-) B. pertussis and cases caused by B. pertussis producing pertactin (PRN(+)) (P = .01). The proportion reporting individual pertussis symptoms was similar between the 2 groups, except a higher proportion of PRN(+) case-patients reported apnea (P = .005). Twenty-two case-patients were hospitalized; 6% in the PRN(+) group compared to 3% in the PRN(-) group (P = .11). Case-patients having received at least 1 pertussis vaccine dose had a higher odds of having PRN(-) B. pertussis compared with unvaccinated case-patients (adjusted OR = 2.2; 95% confidence interval [CI], 1.3-4.0). When restricted to case-patients at least 1 year of age and those age-appropriately vaccinated, the adjusted OR increased to 2.7 (95% CI, 1.2-6.1).

CONCLUSIONS

The significant association between vaccination and isolate pertactin production suggests that the likelihood of having reported disease caused by PRN(-) compared with PRN(+) strains is greater in vaccinated persons. Additional studies are needed to assess whether vaccine effectiveness is diminished against PRN(-) strains.

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.

Population diversity among Bordetella pertussis isolates, United States, 1935-2009

Resurgence of pertussis was not directly correlated with changes in vaccine composition or schedule.

Since the 1980s, pertussis notifications in the United States have been increasing. To determine the types of Bordetella pertussis responsible for these increases, we divided 661 B. pertussis isolates collected in the United States during 1935–2009 into 8 periods related to the introduction of novel vaccines or changes in vaccination schedule. B. pertussis diversity was highest from 1970–1990 (94%) but declined to ≈70% after 1991 and has remained constant. During 2006–2009, 81.6% of the strains encoded multilocus sequence type prn2-ptxP3-ptxS1A-fim3B, and 64% were multilocus variable number tandem repeat analysis type 27. US trends were consistent with those seen internationally; emergence and predominance of the fim3B allele was the only molecular characteristic associated with the increase in pertussis notifications. Changes in the vaccine composition and schedule were not the direct selection pressures that resulted in the allele changes present in the current B. pertussis population.

Increasing burden of invasive group B streptococcal disease in nonpregnant adults, 1990-2007

BACKGROUND

Group B Streptococcus (GBS), traditionally considered to be a neonatal pathogen, is an important cause of morbidity and mortality among older adults and among those with underlying medical conditions. We used population-based surveillance to examine trends in adult GBS disease during the period 1990-2007 and to describe the epidemiology of adult GBS disease to guide prevention efforts.

METHODS

Active Bacterial Core surveillance was conducted in selected counties in 10 US states. A case was defined as isolation of GBS from a normally sterile site in a nonpregnant resident of a surveillance area who was 18 years of age. Rates were calculated using US Census data. Demographic and clinical information was abstracted from medical records. Serotyping and susceptibility testing were performed on isolates collected from a subset of case patients.

RESULTS

A total of 19,512 GBS cases were identified in nonpregnant adults during 1990-2007 (median patient age, 63 years); the incidence of adult GBS disease doubled from 3.6 cases per 100,000 persons during 1990 to 7.3 cases per 100,000 persons during 2007 (P < .001). The mean difference in incidence between black and white persons was 4.6 cases per 100,000 persons (range, 3.1 cases per 100,000 persons during 1991 to 5.8 cases per 100,000 persons during 1999). Common clinical syndromes in 2007 included bacteremia without focus (39.3%), skin and/or soft-tissue infection (25.6%), and pneumonia (12.6%). Most (88.0%) GBS cases in adults had 1 underlying condition; diabetes was present in 44.4% of cases. Serotypes V, Ia, II, and III accounted for 80.8% of infections during 1998-1999 and 78.5% of infections during 2005-2006.

CONCLUSIONS

Invasive GBS disease in nonpregnant adults represents a substantial and increasing burden, particularly among older persons, black persons, and adults with diabetes. Prevention strategies are needed.

Cluster of deaths from group A streptococcus in a long-term care facility--Georgia, 2001

BACKGROUND

Invasive group A streptococcus (GAS) affects approximately 10,500 persons annually; 1 in 5 patients >/=65 years die. In August 2001, CDC investigated a cluster of GAS deaths in a Georgia long-term care facility (LTCF).

METHODS

We screened LTCF residents and staff for GAS carriage and conducted a retrospective cohort study among residents. We defined a case as GAS isolation associated with clinical infection.

RESULTS

Eight cases were identified (median age: 79 years); 6 (75%) patients died. Carriage was similar in residents (10%) and staff (9%). All isolates among residents and 63% among staff were type emm 77. Risk factors for GAS disease or carriage among residents were receiving skin treatment (relative risk [RR] = 4.0, 95% confidence interval [CI] = 1.9-11.0) and having an infected or colonized roommate (RR = 2.0, 95% CI = 1.10-5.0). No wound care nurse carried GAS. Interventions included education about standardized infection control guidelines and appropriate hand hygiene; carriers were treated with antibiotics. No subsequent GAS cases were identified in the following year.

CONCLUSIONS

Transmission of GAS in this outbreak likely occurred during wound care and ended with improved hand hygiene. This investigation highlights additional research and policy needs for control of severe GAS infections among the high-risk LTCF population.