Vaccination timeliness and completeness among preterm and low birthweight infants: a national cohort study

ABSTRACT

Vaccinating premature and low birthweight (LBW) infants according to chronological age has been found safe and effective. Although these infants are susceptible to infections, vaccinations are often delayed. We estimated vaccination coverage (VC) in preterm and LBW infants compared to term infants in a cohort study (2016 Israel birth cohort, n = 181,543) using the National Immunization Registry. Vaccinations included Hepatitis B, Diphtheria-Tetanus-acellular Pertussis-IPV-Haemophilus influenzae B, Oral Polio Bivalent, Rotavirus, Pneumococcal Conjugate, Measles-Mumps-Rubella-Varicella and Hepatitis A. Inclusion criteria: (1) born in Israel; (2) having a unique identifier (allowing data matching); and (3) surviving to 24 months. VC at 24 months and timeliness of vaccine doses were evaluated according to infants’ birthweight (BW) and gestational age (GA). Preterm infants (GA < 37 weeks) comprised 7.0% (n = 12,264); LBW infants (BW< 2500 g) were 7.7% (n = 13,950); BW was 1500–2499 g in 6.8%, 1000–1499 g in 0.6% and below 1000 g in 0.3%. Compared to normal birthweight (NBW) infants (BW≥2500 g), LBW infants showed delayed initiation of vaccinations. Odds ratio (OR) for delay: DTaP-IPV-Hib 1 OR = 1.26 [95%CI 1.19–1.33]; Rota 1, OR = 1.22 [95%CI 1.16–1.29]. Vaccination delay rates were higher among smaller new-borns (below 1000 g). At 24 months there was no significant difference regarding vaccination status. This national cohort VC analysis focused on preterm/LBW infants. Vaccinating preterm and LBW infants according to the recommended schedule induces protection against life-threatening infectious diseases. Vaccination initiation among LBW infants showed considerable delay. Health practitioners and parents should cooperate to improve timely vaccination initiation.

KEYWORDS:

• Vaccination
• vaccination coverage
• low birthweight
• preterm infants
• public health

Acknowledgments

The authors wish to acknowledge the support of Ziona Haklai MA, Head of Health Information Division, Israel Ministry of Health, Hanna Shoob MPH, and Zoey Gotlieb, Jerusalem District Health Office, Nesia Cohen, Computing Division, Ministry of Health.

Author contributions

Both authors either participated in the design, implementation or analysis, and interpretation of the study, as well as the development of this manuscript. Both authors had full access to the data and granted their final approval of the paper before submission.

Disclosure of potential conflicts of interest

No potential conflicts of interest were disclosed.

Additional information

Funding

This study was financially supported by the Office of the Chief Scientist, the Israel Ministry of Health, [grant number MOHIG 010 2017]. The funding sources had no role in the design or conduct of the study; collection, management, analysis and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.