Flu season moderate, not 'mutant'

The media has misrepresented the current influenza season based on testing numbers rather than test positivity rates, generating unnecessary fear in the community, according to the authors of a letter published online by the Medical Journal of Australia.

Dr. Vicky Sheppeard, Director of the Communicable Diseases Branch at NSW Health, and colleagues wrote that so far the 2019 influenza season had been "moderate," in stark contrast to media headlines such as "Mutant flu crisis," and "Exclusive: Jab fail fears as killer strain takes hold" (Daily Telegraph, Saturday 6 July, 2019).

Due to a change from influenza diagnosis based on serology to rapid, highly discriminatory polymerase chain reaction testing, the number of tests skyrocketed in NSW from 29 232 in 2010 to 338 828 in just the first 6 months of 2019.

"We need to look to other indicators to assess the burden of influenza rather than the raw notification numbers," wrote Sheppeard and colleagues.

"One indicator is the influenza test positivity rate.

"This was highest in 2017 (an acknowledged severe season due to ineffectiveness of the vaccine against the predominant influenza A [H3N2] strain) and is at a moderate level so far in 2019.

"Also important to monitor as indicators are hospital admissions of people presenting to emergency departments with influenza-like illness, and mortality from influenza and pneumonia, both of which also show 2019 to be a moderate severity influenza season to date," they wrote.

"Of course, influenza is a serious infection, with a mortality rate of around 1% in confirmed cases and most of the mortality burden affecting the vulnerable elderly.

"We are working to reduce the impact of influenza on the community; hopefully, we can achieve this without generating unfounded community concern."