Vaccination timeliness and delay in low- and middle-income countries: a systematic review of the literature, 2007-2017

ABSTRACT

Background: Traditional measurements of vaccine coverage at specific ages can mask poor vaccine timeliness. However, optimal measurement of timing is unclear due to variations in countries’ recommended vaccination schedules and lack of a commonly accepted standard for “timeliness”. We conducted a systematic review of literature on vaccine timeliness and delay in low- and middle-income countries from 2007 to 2017.

Methods: A search of articles published between January 1 2007 and December 31 2017, was performed in PubMed, EBSCOhost, and Embase.

Results: 67 papers were included, of which 83% used a categorical measure of delay and 41% evaluated continuous delay. The most common age at assessment was 1 month, with earlier age benchmarks typically used with birth doses.

Conclusions: Categorical definitions of vaccination timing vary widely, with benchmarks of delay varying from days to weeks to months. Use of a continuous measure of vaccine delay may be more informative and comparable.

KEYWORDS:

• Vaccine timeliness
• vaccine coverage
• expanded program on immunization

Abbreviations

ANC	=	Antenatal Care
BCG	=	Bacillus Calmette-Guérin
DHS	=	Demographic Health Survey
DTP	=	Diphtheria-tetanus-pertussis vaccine
EPI	=	Expanded Program on Immunization
HepB	=	Hepatitis B
HPV	=	Human papillomavirus
MCV	=	Measles-containing vaccine
MICS	=	Multiple Indicator Cluster Survey or MICS
Hib	=	Haemophilus influenzae type b
IIS	=	Immunization Information System
IPV	=	Inactivated polio vaccine
LMICs	=	Low- or middle-income country
OPV	=	Oral polio vaccine
PCV	=	Pneumococcal conjugate vaccine
WHO	=	World Health Organization

Acknowledgments

We appreciate the work of all the researchers who contributed to the literature on vaccination timeliness.

Disclosure of Potential Conflicts of Interest

No potential conflict of interest was reported by the authors.

Authors’ contributions

ALW contributed to study design, helped review articles, and wrote the first draft of the manuscript. NBM reviewed articles and performed analysis. MLB contributed to study design. All authors revised the manuscript for important intellectual content and gave approval for this version to be published.

Additional information

Funding

ALW’s salary was supported by the National Institute Of Allergy And Infectious Diseases of the National Institutes of Health under Award Number K01AI137123. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health;National Institute of Allergy and Infectious Diseases [K01AI137123];