Description

Author information:
1. Centers for Disease Control and Prevention, Atlanta, GA, USA.
2. Pan American Health Organization, Washington, DC, USA.
3. Universidad del Valle de Guatemala, Guatemala City, Guatemala.
4. Centro Nacional de Influenza, Laboratorio de Virología, Instituto Nacional De Salud, Bogotá, Colombia.
5. Centro Nacional de Influenza, Centro Nacional de Referencia de Virología, Instituto Costarricense de Investigación y Enseñanza en Nutrición y Salud, San Jose, Costa Rica.
6. Centro Nacional de Influenza, Departamento de Virología, Instituto de Medicina Tropical ‟Pedro Kouríˮ, Havana, Cuba.
7. El Centro de Referencia Nacional de Influenza y Otros Virus Respiratorios Insituto Nacional de Investigacion en Salud Publica (INSPI), Quito, Ecuador.
8. Unidad de Vigilancia Laboratorial Dr. Max Bloch, Centro Nacional de Influenza, San Salvador, El Salvador.
9. Centro Nacional de Influenza, Laboratorio Nacional de Salud, Ciudad de Guatemala, Guatemala City, Guatemala.
10. Departamento de Laboratorio Nacional de Vigilancia de la Salud, Tegucigalpa, Honduras.
11. National Influenza Centre-Jamaica, Department of Microbiology, University of West Indies, Kingston, Jamaica.
12. PAHO/WHO Jamaica, National Influenza Centre-Jamaica, Department of Microbiology, University of West Indies, Kingston, Jamaica.
13. National Influenza Centre, Instituto de Diagnóstico y Referencia Epidemiológicos (InDRE), Ministry of Health, Mexico City, Mexico.
14. Laboratorio Nacional de Virología, Centro Nacional de Diagnóstico y Referencia, Ministry of Health, Managua, Nicaragua.
15. Depto. de Investigación en Virología Instituto Conmemorativo Gorgas, Panamá City, Panamá
16. Laboratorio Central de Salud Pública, Asunción, Paraguay.
17. Instituto Nacional de Salud, Lima, Peru.

BACKGROUND:
Influenza-associated illness results in increased morbidity and mortality in the Americas. These effects can be mitigated with an appropriately chosen and timed influenza vaccination campaign. To provide guidance in choosing the most suitable vaccine formulation and timing of administration, it is necessary to understand the timing of influenza seasonal epidemics.
OBJECTIVES:
Our main objective was to determine whether influenza occurs in seasonal patterns in the American tropics and when these patterns occurred.
METHODS:
Publicly available, monthly seasonal influenza data from the Pan American Health Organization and WHO, from countries in the American tropics, were obtained during 2002-2008 and 2011-2014 (excluding unseasonal pandemic activity during 2009-2010). For each country, we calculated the monthly proportion of samples that tested positive for influenza. We applied the monthly proportion data to a logistic regression model for each country.
RESULTS:
We analyzed 2002-2008 and 2011-2014 influenza surveillance data from the American tropics and identified 13 (81%) of 16 countries with influenza epidemics that, on average, started during May and lasted 4 months.
CONCLUSIONS:
The majority of countries in the American tropics have seasonal epidemics that start in May. Officials in these countries should consider the impact of vaccinating persons during April with the Southern Hemisphere formulation.

© 2015 The Authors. Influenza and Other Respiratory Viruses Published by John Wiley & Sons Ltd.
PMCID: PMC4814866 Free PMC Article
PMID: 26701079 [Indexed for MEDLINE]

Publication type
• Research Support, U.S. Gov’t, P.H.S.
MeSH terms
• Brazil/epidemiology
• Epidemiological Monitoring
• Humans
• Influenza Vaccines*/chemistry
• Influenza, Human/epidemiology*
• Influenza, Human/prevention & control*
• Influenza, Human/virology
• Nicaragua/epidemiology
• Pandemics/prevention & control
• Pandemics/statistics & numerical data*
• Peru/epidemiology
• Population Surveillance
• Seasons
• Time Factors
• Tropical Climate*
• United States/epidemiology
• Vaccination
Substance
• Influenza Vaccines