Typical Monthly Influenza Activity Across the Globe

Koen Swinkels
2 min readDec 3, 2021

For every country in the world find out when flu season is.

In the table below find your country and see typical influenza activity for each month. For Brazil, China, India, Mexico and the United States the table also includes provincial or state level data.

Influenza activity levels are based on the historical averages from the years before SARS-CoV-2.

The table is part of the ‘Epidemic Waves’ project in which we summarize and visualize typical influenza activity patterns across the world.

You can:

  • scroll down in the table to find the country or state you would like influenza data for
  • click on any cell, press ‘ctrl+f’ and start typing the name of the country or state

If the searchable table doesn’t load you can go to the table in Google sheets and search there.

You can also view an animated map and timeline of global influenza activity, and zoom in on the country or region you would like more information about.


Measuring and Representing Influenza Activity

We use data from the World Health Organization’s Global Influenza Surveillance and Response System’s FluNet to:

  • look at the past three years (2017–2019) and calculate for each country the average level of influenza activity for a year
  • then check for each of the 12 months of the year how many times influenza activity in that month was above the average for that year
  • use this as the basis to give that month a score on a scale from 1–4

For example, if in France in January there was above average activity in all three years, it receives a score of 4 (1 as the base score, and 1 for each year). If there was above average activity in January in only one of those three years, it receives a score of 2.

It is important to note that this scale of 1–4 does not express the average *intensity* of influenza activity in a month. Instead, it expresses how many times in the past three (or more) years influenza activity was above the annual average.

If we had taken the average intensity for a month over that three year period, then if the intensity was extremely high in one year but below average in the other two years, it could have still come out as a high intensity month. But such a number would tell us less about what we are after: how influenza viruses typically travel across the globe, how common it is for there to be significant influenza activity in a given month.

For subnational data for Brazil, China, India, Mexico and the United States we used different methods and sources to represent influenza activity. For more information, see here.