Pertussis Vaccine Effectiveness Among Children 6 to 59 Months of Age in the United States, 1998–2001

Abstract

ABSTRACT. Background. Despite the dramatic pertussis decrease since the licensure of whole-cell pertussis (diphtheria-tetanus toxoids-pertussis [DTP]) vaccines in the middle 1940s, pertussis remains endemic in the United States and can cause illness among persons at any age; >11 000 pertussis cases were reported in 2003. Since July 1996, in addition to 2 DTP vaccines already in use, 5 acellular pertussis (diphtheria-tetanus toxoids-acellular pertussis [DTaP]) vaccines were licensed for use among infants; 3 DTaP vaccines were distributed widely during the study period. Because of the availability of 3 DTaP and 2 DTP vaccines and the likelihood of the vaccines being used interchangeably to vaccinate children with the recommended 5-dose schedule, measuring the effectiveness of the pertussis vaccines was a high priority.Objective. To measure the pertussis vaccine effectiveness (VE) among US children 6 to 59 months of age.Design. We conducted a case-control study in the Cincinnati, Ohio, metropolitan area, Colorado, Idaho, and Minnesota.Participants. Confirmed pertussis cases among children 6 to 59 months of age at the time of disease onset, with onset in 1998 -2001, were included. For each case subject, 5 control children were matched from birth certificate records, according to the date of birth and residence.Outcome Measures. A standardized questionnaire was used to obtain vaccination data from parents and providers. Parents/guardians were asked about demographic characteristics, child care attendance, the number of household members who stayed at the same home as the enrolled child for >2 nights per week, and cough illness of >2-week duration among these household members in the month before the case patient's cough onset. Pertussis vaccine doses among case children were counted as valid if they were received >14 days before the cough onset date ("valid period"). The age of the case patient (in days) at the end of the valid period was determined, and doses of vaccine for the matched control subjects were counted as valid if they were received by that age. Conditional logistic regression models were used to estimate the matched odds ratios (ORs) for pertussis according to the number of pertussis vaccine doses. The VE was calculated with the following formula: (1 ؊ OR) ؋ 100. Because the pertussis antigen components or amounts differed according to vaccine, the VE of 3 or 4 doses of DTP and/or DTaP was estimated according to the recorded vaccine manufacturer and vaccine type.Results. All enrolled children (184 case subjects and 893 control subjects) had their vaccine history verified. The proportions of children who received 0, 1 or 2, 3, and >4 pertussis (DTP and/or DTaP) vaccine doses among case subjects were 26%, 14%, 26%, and 34% and among control subjects were 2%, 8%, 33%, and 57%, respectively. Compared with 0 doses, the unadjusted VE estimate for 1 or 2 pertussis doses was 83.6% (95% confidence interval [CI]: 61.1-93.1%), that for 3 doses was 95.6% (95% CI: 89.7-98.0%), and for >4 doses was 97.7% (95% CI: 94...

Duration of Protection After First Dose of Acellular Pertussis Vaccine in Infants

“…27 Importantly, children 2 to 3 years of age commonly have younger siblings and may play an important role in the transmission of infection to unimmunized infants, vulnerable to severe disease. [28][29][30] Of the few studies of field effectiveness of acellular pertussis vaccines in children ,5 years of age, [3][4][5][6] none separately estimated VE for the first and second year of life or evaluated changes in VE after 2 years of age. The US study estimated that the effectiveness of 3 doses of pertussis-containing vaccine in children aged ,2 years was 91.7% (95% CI, 74.5%-97.3%), but some 30% of cases had received whole cell vaccine.…”

“…The US study estimated that the effectiveness of 3 doses of pertussis-containing vaccine in children aged ,2 years was 91.7% (95% CI, 74.5%-97.3%), but some 30% of cases had received whole cell vaccine. 3 In Denmark, where an acellular pertussis vaccine containing only pertussis toxin is exclusively used, but with a later third dose, VE for 3 doses among children aged ,2 years was estimated to be 78% (95% CI, 59%-88%) and 93% (95% CI, 78%-98%) for nonhospitalized and hospitalized cases, respectively. 5 In contrast to our results, …”

“…1,2 Postlicensure studies of the effectiveness of fewer doses of DTaP among younger children are limited, [3][4][5][6] and schedule recommendations for acellular pertussis vaccines vary between countries. 7 In addition, there are concerns that changes in the clonal composition of Bordetella pertussis strains, recently documented in Australia 8 and elsewhere, 9 may have resulted in declining vaccine effectiveness against, or increased severity of, pertussis in young children.…”

Transfusion of IgG-Opsonized Foreign Red Blood Cells Mediates Reduction of Antigen-Specific B Cell Priming in a Murine Model

“…The suppressive effect of IgG on the Ab response in the recipient has been termed Ab-mediated immune suppression (AMIS) 3 (2). The effectiveness of anti-D commonly exceeds that of the vaccine preparations, such as measles-mumpsrubella or diphtheria-tetanus toxoids-pertussis vaccines (3,4). The inhibitory AMIS effect is also observed with some vaccines; e.g., the Ab response in vaccinated infants may be down-modulated by the presence of maternal vaccine-specific IgG Ab that crosses the placenta during pregnancy (5).…”

Pertussis

“…Historically, the first study of this type was performed in Sweden; 57-59 studies followed in Denmark, 60,61 USA, 62,63 Austria, 64 and the Netherlands. 65 Overall effectiveness was high and exceeded 92-95% in subjects treated with three doses of acellular vaccine; however, while a decline in the incidence in the target age groups of vaccine intervention was observed in the various settings, the overall average incidence increased in unimmunized children aged 0-2 months, in children aged over 9 years, in adolescents and adults.…”