AISR – 2020 national influenza season summary

The Australian Influenza Surveillance Report (AISR) – 2021 provides a national influenza season summary. It includes information about influenza activity, severity, impact, at-risk populations, virology, and vaccine match and effectiveness.

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AISR – 2020 national influenza season summary

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Publication date:
Last updated:
Publication type:
Report
Audience:
Health sector
Language:
English
Description:

The Australian Influenza Surveillance Report (AISR) is compiled from several data sources used to monitor influenza activity and severity in the community. These data sources include:

  • laboratory-confirmed notifications to NNDSS
  • influenza associated hospitalisations
  • sentinel influenza-like illness (ILI) reporting from general practitioners
  •  ILI-related community level surveys
  • sentinel laboratory testing results.

The AISR is published fortnightly during the influenza season, typically between May and October. Influenza activity updates may be published outside of the seasonal period.

Key messages

It is important to note that due to the COVID-19 epidemic in Australia, data reported from the various influenza surveillance systems may not accurately reflect influenza activity. Results should be interpreted with caution, especially where comparisons are made to previous influenza seasons. Interpretation of 2020 influenza activity data should take into account, but are not limited to, the impact of physical distancing measures, likely changes in health seeking behaviour of the community including access to alternative streams of acute respiratory infection specific health services, and focussed testing for COVID-19 response activities. During 2020, COVID-19 related public health measures and the community’s adherence to public health messages are also likely to have had an effect on transmission of acute respiratory infections, including influenza.

Activity

Following a high start to the 2020 interseasonal period, influenza and influenza-like illness (ILI) activity levels were lower than average across all systems. At the national level, notifications of laboratory-confirmed influenza substantially decreased in mid-March and remained low since.

Impact

Given low case numbers of laboratory-confirmed notifications for influenza, it is likely that there is minimal impact on society due to influenza circulation in the 2020 season.

Severity

There is no indication of the potential severity during the 2020 season. In the year to date, of the 21,266 notifications of laboratory confirmed influenza, 37 (0.17%) laboratory-confirmed influenza-associated deaths have been notified to the National Notifiable Diseases Surveillance System (NNDSS).

At-risk populations

Children younger than 10 years of age had the highest influenza notification rate, while the notification rate among those aged 65 years or older was lower compared to other age groups.

Virology

In the year to date in 2020, the majority of nationally reported laboratory-confirmed influenza cases were influenza A (87.1%).

Vaccine match and effectiveness

The low case numbers of influenza across all systems during the 2020 season precludes meaningful analysis to estimate vaccine effectiveness. Of the samples referred to the WHOCC, there was reasonable matching between influenza subtype and lineage, and the corresponding vaccine component.

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