Beijing, Jan 3 (IANS): The Covid-19 pandemic changed the epidemic trend of influenza, an acute respiratory infectious disease, and in China, a significant decrease in influenza activity was observed during the pandemic, researchers have revealed.

The study by researchers at Peking University's School of Public Health provides preliminary evidence of the long-term relationship between prevention and control measures and influenza transmission in China during the pandemic.

"The Covid-19 outbreak changed the epidemic trend and characteristics of influenza, according to our analysis," said Professor Min Liu in the study published in Health Data Science, a Science Partner Journal.

A marked decrease in influenza activity was also registered in Japan and the US, among other regions in the Northern Hemisphere, in early 2020.

In addition, Australia, Chile, and other areas in the Southern Hemisphere shared this observation during their influenza season in 2020.

In China, influenza seasonality was evident from 2010 to 2019 but absent during the 2020/2021 season across the country, whether north or south.

Reduction of influenza viral infection might be related to everyday public health interventions in China, said the authors.

Respiratory diseases frequently occur in winter and spring when Covid-19 and influenza tend to circulate easily.

Meanwhile, the resurgence of other respiratory viruses once suppressed under Covid-19 in 2020-2021 has been recognised worldwide.

To protect these vulnerable populations, besides increasing influenza vaccine coverage, efforts should be paid to strengthen influenza surveillance and establish a comprehensive surveillance system for influenza virus and SARS-CoV-2, the researchers noted.