Pertussis Vaccine Effectiveness in the Setting of Pertactin-Deficient Pertussis.

BACKGROUND: In the United States, the proportion of Bordetella pertussis isolates lacking pertactin, a component of acellular pertussis vaccines, increased from 14% in 2010 to 85% in 2012. The impact on vaccine effectiveness (VE) is unknown. METHODS: We conducted 2 matched case-control evaluations in Vermont to assess VE of the 5-dose diphtheria, tetanus, and acellular pertussis vaccine (DTaP) series among 4- to 10-year-olds, and tetanus, diphtheria, and acellular pertussis vaccine (Tdap) among 11- to 19-year-olds. Cases reported during 2011 to 2013 were included. Three controls were matched to each case by medical home, and additionally by birth year for the Tdap evaluation. Vaccination history was obtained from medical records and parent interviews. Odds ratios (OR) were calculated by using conditional logistic regression; VE was estimated as (1-OR) × 100%. Pertactin status was determined for cases with available isolates. RESULTS: Overall DTaP VE was 84% (95% confidence interval [CI] 58%-94%). VE within 12 months of dose 5 was 90% (95% CI 71%-97%), declining to 68% (95% CI 10%-88%) by 5-7 years post-vaccination. Overall Tdap VE was 70% (95% CI 54%-81%). Within 12 months of Tdap vaccination, VE was 76% (95% CI 60%-85%), declining to 56% (95% CI 16%-77%) by 2-4 years post-vaccination. Of cases with available isolates, >90% were pertactin-deficient. CONCLUSIONS: Our DTaP and Tdap VE estimates remain similar to those found in other settings, despite high prevalence of pertactin deficiency in Vermont, suggesting these vaccines continue to be protective against reported pertussis disease.

Tdap vaccine effectiveness in adolescents during the 2012 Washington State pertussis epidemic.

BACKGROUND: Acellular pertussis vaccines replaced whole-cell vaccines for the 5-dose childhood vaccination series in 1997. A sixth dose of pertussis-containing vaccine, tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis, adsorbed (Tdap), was recommended in 2005 for adolescents and adults. Studies examining Tdap vaccine effectiveness (VE) among adolescents who have received all acellular vaccines are limited. METHODS: To assess Tdap VE and duration of protection, we conducted a matched case-control study during the 2012 pertussis epidemic in Washington among adolescents born during 1993-2000. All pertussis cases reported from January 1 through June 30, 2012, in 7 counties were included; 3 controls were matched by primary provider clinic and birth year to each case. Vaccination histories were obtained through medical records, the state immunization registry, and parent interviews. Participants were classified by type of pertussis vaccine received on the basis of birth year: a mix of whole-cell and acellular vaccines (1993-1997) or all acellular vaccines (1998-2000). We used conditional logistic regression to calculate odds ratios comparing Tdap receipt between cases and controls. RESULTS: Among adolescents who received all acellular vaccines (450 cases, 1246 controls), overall Tdap VE was 63.9% (95% confidence interval [CI]: 50% to 74%). VE within 1 year of vaccination was 73% (95% CI: 60% to 82%). At 2 to 4 years postvaccination, VE declined to 34% (95% CI: -0.03% to 58%). CONCLUSIONS: Tdap protection wanes within 2 to 4 years. Lack of long-term protection after vaccination is likely contributing to increases in pertussis among adolescents.

Special considerations for prophylaxis for and treatment of anthrax in pregnant and postpartum women.

In August 2012, the Centers for Disease Control and Prevention, in partnership with the Association of Maternal and Child Health Programs, convened a meeting of national subject matter experts to review key clinical elements of anthrax prevention and treatment for pregnant, postpartum, and lactating (P/PP/L) women. National experts in infectious disease, obstetrics, maternal fetal medicine, neonatology, pediatrics, and pharmacy attended the meeting, as did representatives from professional organizations and national, federal, state, and local agencies. The meeting addressed general principles of prevention and treatment for P/PP/L women, vaccines, antimicrobial prophylaxis and treatment, clinical considerations and critical care issues, antitoxin, delivery concerns, infection control measures, and communication. The purpose of this meeting summary is to provide updated clinical information to health care providers and public health professionals caring for P/PP/L women in the setting of a bioterrorist event involving anthrax.

Association of childhood pertussis with receipt of 5 doses of pertussis vaccine by time since last vaccine dose, California, 2010.

CONTEXT: In 2010, California experienced its largest pertussis epidemic in more than 60 years; a substantial burden of disease was noted in the 7- to 10-year-old age group despite high diphtheria, tetanus, and acellular pertussis vaccine (DTaP) coverage, indicating the possibility of waning protection. OBJECTIVE: To evaluate the association between pertussis and receipt of 5 DTaP doses by time since fifth DTaP dose. DESIGN, SETTING, AND PARTICIPANTS: Case-control evaluation conducted in 15 California counties. Cases (n = 682) were all suspected, probable, and confirmed pertussis cases among children aged 4 to 10 years reported from January through December 14, 2010; controls (n = 2016) were children in the same age group who received care from the clinicians reporting the cases. Three controls were selected per case. Vaccination histories were obtained from medical records and immunization registries. MAIN OUTCOME MEASURES: Primary outcomes were (1) odds ratios (ORs) for the association between pertussis and receipt of the 5-dose DTaP series and (2) ORs for the association between pertussis and time since completion (<12, 12-23, 24-35, 36-47, 48-59, or ≥60 months) of the 5-dose DTaP series. Logistic regression was used to calculate ORs, accounting for clustering by county and clinician, and vaccine effectiveness (VE) was estimated as (1 - OR) × 100%. RESULTS: Among cases and controls, 53 (7.8%) and 19 (0.9%) had not received any pertussis-containing vaccines, respectively. Compared with controls, children with pertussis had a lower odds of having received all 5 doses of DTaP (OR, 0.11; 95% CI, 0.06-0.21 [estimated VE, 88.7%; 95% CI, 79.4%-93.8%]). When children were categorized by time since completion of the DTaP series, using an unvaccinated reference group, children with pertussis compared with controls were less likely to have received their fifth dose within the prior 12 months (19 [2.8%] vs 354 [17.6%], respectively; OR, 0.02; 95% CI, 0.01-0.04 [estimated VE, 98.1%; 95% CI, 96.1%-99.1%]). This association was evident with longer time since vaccination, with ORs increasing with time since the fifth dose. At 60 months or longer (n = 231 cases [33.9%] and n = 288 controls [14.3%]), the OR was 0.29 (95% CI, 0.15-0.54 [estimated VE, 71.2%; 95% CI, 45.8%-84.8%]). Accordingly, the estimated VE declined each year after receipt of the fifth dose of DTaP. CONCLUSION: Among children in 15 California counties, children with pertussis, compared with controls, had lower odds of having received the 5-dose DTaP series; as time since last DTaP dose increased, the odds increased, which is consistent with a progressive decrease in estimated vaccine effectiveness each year after the final dose of pertussis vaccine.