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.

Although invasive streptococcal infections do not appear to be more severe in pregnant or postpartum women, postpartum women have a 20-fold increased incidence of GAS and GBS, compared with nonpregnant women.

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 January 1, 2011 and December 31, 2014 from six U.S. 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 – OR) × 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 3rd trimester of pregnancy. The multivariable VE estimate for Tdap administered during the third trimester of pregnancy was 77.7% (48.3% – 90.4%); VE increased to 90.5% (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.

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.

This systematic review suggests that there is significant benefit in prevention of Rotavirus diarrhea among children by practicing exclusive breastfeeding throughout first 6 mo of life. Thereby, this study provides next reason to promote exclusive breastfeeding practice among mothers.