Expansion of seasonal influenza vaccination in the Americas

Abstract

Background: Seasonal influenza is a viral disease whose annual epidemics are estimated to cause three to five million cases of severe illness and 250,000 to 500,000 deaths worldwide. Vaccination is the main strategy for primary prevention.

Methods: To assess the status of influenza vaccination in the Americas, influenza vaccination data reported to the Pan American Health Organization (PAHO) through 2008 were analyzed.

Results: Thirty-five countries and territories administered influenza vaccine in their public health sector, compared to 13 countries in 2004. Targeted risk groups varied. Sixteen countries reported coverage among older adults, ranging from 21% to 100%; coverage data were not available for most countries and targeted populations. Some tropical countries used the Northern Hemisphere vaccine formulation and others used the Southern Hemisphere vaccine formulation. In 2008, approximately 166.3 million doses of seasonal influenza vaccine were purchased in the Americas; 30 of 35 countries procured their vaccine through PAHO's Revolving Fund.

Conclusion: Since 2004 there has been rapid uptake of seasonal influenza vaccine in the Americas. Challenges to fully implement influenza vaccination remain, including difficulties measuring coverage rates, variable vaccine uptake, and limited surveillance and effectiveness data to guide decisions regarding vaccine formulation and timing, especially in tropical countries.

Figure 1

Number of countries and territories in the Americas with public policies regarding seasonal influenza vaccination (1970s-2008). Note: Data not collected from the French Departments (French Guiana, Guadeloupe, and Martinique). Source: Country and territory reports to PAHO.

Figure 2

Reported 2006 and 2007 seasonal influenza vaccination coverage among elderly populations in selected countries in Latin America. Note: ≥ 65 years in Cuba, Chile (2006), Honduras; ≥ 60 years in Brazil, Chile (2007), El Salvador, Mexico, Panama, and Paraguay. Source: Country and territory reports to PAHO.

Figure 3

Reported 2006 and 2007 seasonal influenza vaccine coverage among children aged 6-23 months in selected countries in Latin America. Source: Country and territory reports to PAHO.

Figure 4

Formulation of seasonal influenza vaccine used in countries and territories of the Americas, 2008. Source: Country and territory reports to PAHO.

Figure 5

Doses of adult and pediatric seasonal influenza vaccine purchased through the PAHO Revolving Fund (RF) for Vaccine Procurement by year. Note: Brazil, Canada, Chile, Mexico, and the United States do not procure vaccine through the RF. Source: Country and territory reports to PAHO.