Human papillomavirus vaccination in Tanzanian schoolgirls: cluster-randomized trial comparing 2 vaccine-delivery strategies

Abstract

Background: We compared vaccine coverage achieved by 2 different delivery strategies for the quadrivalent human papillomavirus (HPV) vaccine in Tanzanian schoolgirls.

Methods: In a cluster-randomized trial of HPV vaccination conducted in Tanzania, 134 primary schools were randomly assigned to class-based (girls enrolled in primary school grade [class] 6) or age-based (girls born in 1998; 67 schools per arm) vaccine delivery. The primary outcome was coverage by dose.

Results: There were 3352 and 2180 eligible girls in schools randomized to class-based and age-based delivery, respectively. HPV vaccine coverage was 84.7% for dose 1, 81.4% for dose 2, and 76.1% for dose 3. For each dose, coverage was higher in class-based schools than in age-based schools (dose 1: 86.4% vs 82.0% [P = .30]; dose 2: 83.8% vs 77.8% [P = .05]; and dose 3: 78.7% vs 72.1% [P = .04]). Vaccine-related adverse events were rare. Reasons for not vaccinating included absenteeism (6.3%) and parent refusal (6.7%). School absenteeism rates prior to vaccination ranged from 8.1% to 23.5%.

Conclusions: HPV vaccine can be delivered with high coverage in schools in sub-Saharan Africa. Compared with age-based vaccination, class-based vaccination located more eligible pupils and achieved higher coverage. HPV vaccination did not increase absenteeism rates in selected schools. Innovative strategies will be needed to reach out-of-school girls.

Clinical trials registration: NCT01173900.

Figure 1.

Study design and participant enrollment. ^aIncludes the 25 girls in 3 schools that refused whose eligibility could not be reassessed on the day of vaccination. ^b“Intervention” is defined as the provision of human papillomavirus (HPV) vaccine through 2 different school-based strategies. ^cBecause the outcome is defined as the receipt of 1, 2, or 3 doses of vaccine by eligible girls, the outcome is known for all eligible girls. Therefore, there is no loss to follow-up in the sense of the outcome being unknown. ^dSecondary analysis included all schools that were randomized.

Figure 2.

Coverage for dose 3 in each school, by school type and delivery strategy. Abbreviation: Govt, government.