| 2007 |
Endemic / lower intensity |
Typical seasonality |
| 2008 |
Endemic / lower intensity |
Typical seasonality |
| 2009 |
Elevated outbreak |
High case counts compared to previous years |
| 2010 |
Endemic |
Moderate transmission |
| 2011 |
Endemic |
Moderate transmission |
| 2012 |
Endemic |
Moderate transmission |
| 2013 |
Endemic |
Moderate transmission |
| 2014 |
Endemic |
Moderate transmission |
| 2015 |
Endemic |
Moderate transmission |
| 2016 |
Endemic |
Moderate transmission |
| 2017 |
Major epidemic |
Record outbreak |
| 2018 |
Endemic |
Lower than 2017 peak |
| 2019 |
Elevated outbreak |
Significant increase |
| 2020 |
Endemic |
Lower post-epidemic |
| 2021 |
Endemic |
Moderate transmission |
| 2022 |
Endemic |
Moderate transmission |
| 2023 |
Elevated outbreak |
Higher than baseline |
| 2024 |
Elevated transmission |
Above normal seasonal levels |
| 2025 |
Elevated outbreak |
Substantial increase, multiple provinces affected |
| 2026 |
Elevated transmission |
High-risk early year transmission |
