Table 1.

Missed opportunities for vaccination and factors associated with undervaccination in children aged <5 years: Literature search--Americas Region, 1980–2013 ^(a)

Results obtained	Medline	Other search engines (b)	Grey literature (c)	Total
Total results	1084	13200	30	14314
“Suggestive” title (d)	178	1597	25	1800
Not related (e)	90	1295	0	1385
Duplicates	9	88	0	97
Not found	30	146	0	176
Not vaccines of the national immunization program	7	18	0	25
Included in the search	42	50	25	117

^(a) Descriptors used: missed opportunities for vaccination; vaccination knowledge, attitudes, and practices; vaccination coverage, causes of no vaccination; children younger than 5 years. Search limits: period 1980–2013; studies written or published in Spanish, English, Portuguese, or French.

^(b) Artemisa, Lilacs, Bireme, Google Scholar, Redalyc.

^(c) The term “grey literature” includes references found in bibliographies of published articles, technical documents and presentations available on Google Scholar, and documents available on PAHO and country websites.

^(d) Articles with a “suggestive title” were considered those that might reasonably have been considered to concern missed opportunities for vaccination.

^(e) Articles in the “not related” category employed some of the descriptors mentioned. However, these articles were excluded for one or more of the following reasons: the country studied was out of the Americas Region; the age group studied was not children aged <5 years; and/or the focus of the article was not on factors associated with MOVs or undervaccination.