Research Article: Progress in Vaccination against Haemophilus influenzae type b in the Americas

Date Published: April 22, 2008

Publisher: Public Library of Science

Author(s): M. Carolina Danovaro-Holliday, Salvador Garcia, Ciro de Quadros, Gina Tambini, Jon K Andrus

Abstract: The authors review the progress to date in Hib vaccine introduction, the lessons learned,
and the remaining challenges.

Partial Text: Worldwide, Haemophilus
influenzae type b (Hib) causes at least 3 million cases of severe disease
each year. Approximately 400,000 children die annually due to pneumonia or meningitis caused
by Hib [1]. Severe
neurological sequelae occur in 15% to 30% of those who survive Hib
meningitis [2].
Other, less frequent, manifestations of Hib are epiglottitis, septic arthritis,
osteomyelitis, and septicemia [1–3].

To assess the progress accomplished by LAC countries in Hib vaccination and the remaining
challenges, we reviewed the Pan American Health Organization (PAHO)’s Technical Advisory
Group (TAG) on Vaccine-preventable Diseases recommendations; annual country immunization
reports to PAHO; Hib-containing vaccine purchase records from PAHO’s Revolving Fund; and Hib
isolation data from selected countries participating in a Regional Laboratory Network for
Surveillance of Bacterial Meningitis and Pneumonia (Sistema Regional de
Vacunas, or SIREVA). We examined data from 1997 to 2006.

To control Hib invasive disease and reduce Hib carriers in the Americas, PAHO’s TAG
recommends, since 1997, that Member States:

By the end of 2006, all countries of the Americas, except Haiti, had included Hib in their
infant immunization schedule (Table
1). As a result, over 98% of the 16 million children born annually in the
Americas live in countries routinely using Hib-containing vaccines. Canada (1986) and the
United States (1991) were among the first countries to introduce Hib vaccine. Bermuda
(1989), the Cayman Islands (1992), and the Dutch territories (1995) were first in the
Caribbean. Uruguay and Chile followed in 1994 and 1996, respectively. Uruguay conducted an
aggressive catch-up introduction of Hib vaccine for all children aged one to four years,
whereas Chile started vaccinating one birth cohort at a time [11,25]. Argentina followed in 1997. However, most countries and territories
(n = 20) introduced Hib vaccine between 1998 and 2000, more
than ten years after the vaccine was first licensed in 1987. In 2006, Dominica was the last
country to introduce Hib vaccine.

Although LAC countries lagged behind North America in their efforts to introduce Hib
vaccine into their childhood immunization schedules, probably due mostly to financial
considerations, all but Haiti had introduced this vaccine by the end of 2006. Even though
the data available regarding Hib is not complete and comes from routine reporting by
countries to PAHO, we believe that the main factors that favored the region-wide adoption of
Hib vaccine in LAC are the safety and effectiveness of conjugated Hib vaccines; strong
political will; the existence of data supporting a high Hib disease burden and vaccination
impact in early adopters, and their lessons learned, shared through several publications and
regional meetings; and PAHO’s efforts to ensure the affordability of Hib vaccines, mainly
through the RF.



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