Timeliness of children's vaccinations in 91 low-income and middle-income countries: an analysis of survey data.

Abstract

For many children in low-income and middle-income countries (LMICs) the actual age of vaccination is later than the recommended target age. We provide updated evidence on the coverage and timeliness of vaccination across a broad and geographically diverse set of LMICs. We included 91 LMICs, using data from 45 Demographic and Health Surveys and 46 Multiple Indicator Cluster Surveys conducted between 2010 and 2019. We calculated coverage by day of age for children younger than 3 years for BCG, hepatitis B birth dose vaccine (HBV0), polio vaccine (Polio0-3), diphtheria-tetanus-pertussis-containing vaccine (DTP1-3), pneumococcal conjugate vaccine (PCV1-3), rotavirus vaccine (RV1-2), and measles-containing vaccine (MCV1-2). We calculated the percentage of doses that were early, timely (0-28 days after the target age), and late, and net delays (actual age at administration minus target age). We compared the coverage and timeliness of BCG and DTP1-3 with co-recommended vaccinations. We devised a curve-fitting method for reproducing estimates of coverage by day of age from birth to younger than 3 years for each vaccine, country, and year. The unweighted median of the net mean delays (mean vaccination age minus target age) was 3·3 weeks (IQR 1·7-4·6) for BCG (90 surveys), 3·7 weeks (2·2-4·9) for DTP1 (91 surveys), 5·2 weeks (3·8-7·3) for DTP2 (91 surveys), 7·7 weeks (5·4-10·7) for DTP3 (91 surveys), 5·5 weeks (4·1-7·8) for MCV1 (86 surveys), and 5·4 weeks (3·7-7·7) for MCV2 (24 surveys). The corresponding median of the net median delays (median vaccination age minus target age) was 1·0 weeks (IQR 0·3-1·9) for BCG, 1·4 weeks (1·0-2·1) for DTP1, 2·6 weeks (1·6-3·6) for DTP2, 3·9 weeks (2·1-5·6) for DTP3, 2·2 weeks (1·6-3·1) for MCV1, and 3·2 weeks (2·4-3·8) for MCV2. The unweighted median percentage of vaccinations that were timely was 79% (71-92) for BCG, 70% (59-81) for DTP1, 59% (46-73) for DTP2, 50% (35-66) for DTP3, 56% (45-64) for MCV1, and 50% (37-55) for MCV2. Median BCG vaccine coverage increased from 73% (59-87) to 93% (85-96) between 1 month and 6 months of age. Median DTP3 coverage increased from 47% (13-65) to 76% (64-88) between 6 months and 12 months of age. Median MCV1 coverage increased from 53% (6-73) to 81% (69-88) between 12 months and 18 months of age. Vaccines co-recommended with BCG (HBV0 and Polio0) and DTP1-3 (Polio1-3, PCV1-3, and RV1-2) had similar timeliness but lower coverage. Many children in LMICs continue to experience substantial delays in vaccination. Strategies to boost vaccine impact should be informed by systematic evidence on vaccine timeliness. WHO through a grant from the Gates Foundation. For the French translation of the abstract see Supplementary Materials section. For the Spanish translation of the abstract see Supplementary Materials section. For the Portuguese translation of the abstract see Supplementary Materials section.