Australia’s cold and flu hotspots

In the winter months in Australia, the risk of catching a cold or flu tends to rise. With colder temperatures, increased time spent indoors and greater exposure to other people can create ideal conditions for respiratory illnesses to spread.  

To uncover Australia’s cold and flu hotspots, health insurance comparison service iSelect analysed a range of factors linked to the transmission of respiratory illnesses to create an index. The research assessed the mean minimum winter temperatures across June, July and August, respiratory infection rates of influenza, Respiratory Syncytial Virus (RSV) and COVID-19, flu vaccination coverage, population density and winter air pollution levels. Together, these factors provide a snapshot of where Australians may face a greater risk of catching a common respiratory illness during the winter months. 

Australia’s cold and flu hotspots index 

According to the index, New South Wales is the easiest place in Australia to catch a cold, driven by the nation’s highest reported rate of respiratory infections. More than 74,000 respiratory illness cases per 100,000 residents were reported over the past six months, including influenza, RSV and COVID-19. While NSW experiences relatively mild winter temperatures compared to more southern states, its large population and highly connected urban areas result in greater opportunities for viruses to spread. Sydney, Australia’s most populated city, is a major hub for commuting and social interactions, all of which can increase exposure to the common cold or flu. 

Victoria placed second in Australia’s cold and flu hotspots index, recording some of the coldest winter temperatures in the country and a high population density. Melbourne’s cool winter conditions, combined with its status as Australia’s second most populated city, create an environment where respiratory illnesses can spread more easily during the colder months. Despite ranking highly on the index, Victoria also recorded one of the stronger flu vaccination rates nationally, which may help reduce the severity and spread of seasonal illnesses. 

Queensland was ranked the third easiest place to catch a cold. Although it experiences warmer winter temperatures than most southern states and has a relatively low population density, it recorded the second-highest number of respiratory infections nationally. The more populated areas, including Brisbane and other major regional cities, could be the culprit of the high infection rates that outweigh some of the protective benefits associated with warmer climates.  

The Australian Capital Territory ranked fourth in the index. While the ACT recorded the coldest average winter temperatures in the study, it also had the highest flu vaccination coverage in Australia. Canberra’s extremely high population density compared to other states and territories may increase opportunities for virus transmission, though strong vaccination uptake may help offset some of this risk, reporting one of the lowest respiratory cases per 100,000 residents in the past 6 months.  

Tasmania ranked fifth in the cold and flu hotspots, recording some of the coldest winter temperatures in the country. Despite its colder climate, Tasmania recorded relatively low respiratory infection rates compared to many other states and territories, which helped keep its overall score lower than higher-ranked states. However, the state recorded the second-highest average PM2.5 air pollution levels which can increase susceptibility to colds. 

Western Australia ranked sixth in iSelect’s cold and flu hotspots index, recording a relatively mild winter compared to colder states with a mean minimum temperature of 7.69°C. The state’s low population density helped reduce its overall score, as fewer people living within proximity can limit opportunities for viruses to spread. Overall, a combination of lower population density and fewer reported respiratory infections helped keep Western Australia among the lower-risk states for catching a cold this winter. 

South Australia ranked second to last in our cold and flu hotspots, with an average minimum winter temperature of 7.08°C and relatively low respiratory infection rates compared to higher-ranked states. The state also recorded one of the lowest population densities in the country paired with one of the stronger flu vaccination rates of 25.45%, potentially helping to limit the spread and severity of common respiratory illnesses. Combined with relatively low air pollution levels, South Australia emerged as one of the lower-risk states for catching a cold this winter, according to the index. 

The Northern Territory ranked as the least likely place in Australia to catch a cold. This was due to the fewest respiratory infections, with just 1,679 cases per 100,000 residents over the past six months, while also benefiting from the warmest winter temperatures in the country, with an average minimum winter temperature of 11.98°C. The NT’s extremely low population density also contributed to its ranking, reducing opportunities for respiratory viruses to spread between residents. While the NT recorded the highest PM2.5 air pollution levels in the index and one of the lowest flu vaccination rates nationally, these factors were outweighed by its warmer climate, lower infection rates and dispersed population.