Seasonality, timing, and climate drivers of influenza activity worldwide

Eduardo Azziz Baumgartner, Christine N Dao, Sharifa Nasreen, Mejbah Uddin Bhuiyan, Syeda Mah-E-Muneer, Abdullah Al Mamun, M A Yushuf Sharker, Rashid Uz Zaman, Po-Yung Cheng, Alexander I Klimov, Marc-Alain Widdowson, Timothy M Uyeki, Stephen P Luby, Anthony Mounts, Joseph Bresee

Research output: Contribution to journalA1: Web of Science-articlepeer-review


BACKGROUND: Although influenza is a vaccine-preventable disease that annually causes substantial disease burden, data on virus activity in tropical countries are limited. We analyzed publicly available influenza data to better understand the global circulation of influenza viruses.

METHOD: We reviewed open-source, laboratory-confirmed influenza surveillance data. For each country, we abstracted data on the percentage of samples testing positive for influenza each epidemiologic week from the annual number of samples testing positive for influenza. The start of influenza season was defined as the first week when the proportion of samples that tested positive remained above the annual mean. We assessed the relationship between percentage of samples testing positive and mean monthly temperature with use of regression models.

FINDINGS: We identified data on laboratory-confirmed influenza virus infection from 85 countries. More than one influenza epidemic period per year was more common in tropical countries (41%) than in temperate countries (15%). Year-round activity (ie, influenza virus identified each week having ≥ 10 specimens submitted) occurred in 3 (7%) of 43 temperate, 1 (17%) of 6 subtropical, and 11 (37%) of 30 tropical countries with available data (P = .006). Percentage positivity was associated with low temperature (P = .001).

INTERPRETATION: Annual influenza epidemics occur in consistent temporal patterns depending on climate.

Original languageEnglish
JournalJournal of Infectious Diseases
Issue number6
Pages (from-to)838-846
Number of pages9
Publication statusPublished - 2012


  • Climate
  • Epidemics/statistics & numerical data
  • Global Health
  • Hand Disinfection
  • Health Policy
  • Humans
  • Hygiene
  • Influenza Vaccines/administration & dosage
  • Influenza, Human/epidemiology
  • Patient Education as Topic
  • Population Surveillance
  • Public Health
  • Seasons
  • Time Factors
  • Vaccination


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