By Andrew Bryan, Deloitte Financial Advisory


This summer’s high profile coverage of the ‘Aussie flu’ outbreak Down Under, got me thinking about how much of the coverage is media hype, and whether there is any available data to support the fears about flu outbreaks in the Northern hemisphere. With the UK now entering the flu season, this week’s blog explores my analysis and key findings.

About Flu: Flu is an acute viral infection of the respiratory tract, usually characterised by a fever, chills, headache, aching muscles, joint pain and fatigue. It is a highly infectious virus different to the common cold, and spreads rapidly in closed communities and even people with mild or no symptoms can infect others. Flu kills an average of 8,000 people every year, and it can be particularly serious in older adults, very young children, and people with underlying health conditions.1

What do the available data show?

First, I needed a data source that gave an indication of popular interest and trending topics, so I turned to Google Trends.2 For the uninitiated, Google Trends shows how frequently a search term is entered into the search engine over a given time period, where 100 is the most popular point with all other scores relative to this. Using ’Flu’ as the search term, I was able to extract data for the past five years, on a Worldwide basis, and specifically Australia, the UK and the US. By visualising this data in Tableau, it was immediately clear that in Australia ‘flu’ searches hit peak popularity in mid-May year after year, and as suggested by the media frenzy, 2019 saw an unusually high spike in such searches (see Figure 1).

Figure 1: Interest trended over the last five years in Australia
Source: Google trends

On a seasonal basis, although the peak is much more prominent in 2019, the trend follows are fairly similar profile to previous years, with the exception of 2017, which saw a greater volume of searches slightly later, in the 3rd quarter (see Figure 2).

Figure 2: Seasonality of Interest in Australia


Source: Google trends

Google Trends also include a ‘Top Risers’ feature, which indicates the search terms involving the word ‘flu’ that have seen the largest increase in search frequency since the previous period. Unsurprisingly, the search term ’Aussie flu’ does not feature in the top rising search terms originating from Australia, but was the largest increasing term in the UK, suggesting that the UK media may be somewhat responsible for the term’s popularity (see Figure 3). This implies there may be something of a ‘chicken and egg’ situation surrounding these data.

Figure 3. Google trends ‘Top risers’ for searches including the word flu



Source: Google trends

So, as shown in Figure 1 above, ‘flu’ was certainly a popular search term in Australia in May of 2019, but do the confirmed cases back this up? I used FluNet (via the World Health Organisation (WHO) website), a global web-based tool for influenza virological surveillance, presenting data on the number of influenza viruses detected by subtype across 159 countries.3 When trend data for Australia is mapped out, it shows that a large spike in positive cases reported in June 2019, reaching 4,354 for the month (see Figure 4).

Figure 4: Positive flu cases by month


Source: WHO/FluNet

In the first 43 weeks of 2019 there was a 315 per cent year-on-year increase in the number of positive cases of flu reported in Australia, which represented the 10th largest 2019 year-on-year increase. When presented in the same time series, there is a clear correlation between people Google searching for ‘flu’ and positive reported cases, particularly for Q3 2017 and May/June 2019 (see Figure 5). This does therefore seem to support the hype around ’Aussie flu’.

Figure 5: Weekly Positive flu cases vs. Interest in Australia


Source: WHO/FluNet, Google trends

What does this mean for us here in the UK?

UK Data for August, September and October 2018 and 2019 show significant year-on-year increases in the number of positive cases, albeit based on relatively small cohorts (see Figure 6). However, Public Health England (PHE) have stated that trends in Australia are not necessarily a clear predictor of the UK’s flu season.4

Figure 6: Monthly year-on-year increase in UK positive cases – 2018 vs. 2019


Source: WHO/FluNet

The key takeaways from this include the fact that Aussie flu is most certainly not fake news with 2019 recording significantly increased levels of positive flu cases, albeit not unprecedented. Furthermore, each year the WHO reviews the global situation (once for the Northern Hemisphere vaccine and once for the Southern Hemisphere) and recommends which flu strains should go in the vaccine that will be manufactured for the following season. This recommendation is based on the viruses circulating each season and epidemiological data from around the world. The recommendations for 2019-20 cover four variants, including the Brisbane variant. PHE has followed these recommendations and acknowledges the potential impact of Aussie flu on the UK, by including ‘Brisbane variant flu’ in this year’s UK Flu vaccine.5

What are the implications of a heightened outbreak of flu in the UK?

In most people, flu is a fairly mild, self-limiting illness. However, for some, particularly those in ‘at-risk’ groups (for example older people, and those with weakened immune systems), all types of flu can be severe and life threatening. Indeed, the UK health and social care sectors are still recovering from the impact of 50,100 excess ‘winter deaths’ in 2017-18 which the Office of National Statistics calculates was the highest recorded since winter 1975 to 1976 (over one-third (34.7 per cent) of these excess winter deaths were caused by respiratory diseases). The ONS noted that it was likely that the increase was due to the predominant strain of flu, the effectiveness of the influenza vaccine and below-average winter temperatures.6 In 2018-19, there were an estimated 1,692 flu associated deaths.7 The flu vaccine is the best defence there is against the spread of flu.8

For employers everywhere, increased sick leave will influence productivity and can affect supply chains and profitability. Consequently, in the increasingly global world in which we live, it’s up to each of us to do what we can to protect ourselves and each other. This includes maintaining good personal health and hygiene habits (frequent hand washing and covering coughs and sneezes), avoiding close contact with sick people; and staying home if sick.9

The WHO recommends flu vaccination for high-risk groups, such as pregnant women, children under five, the elderly, people who have chronic illnesses or are immunocompromised and health care workers, including carers. The UK follows these recommendations and provide free vaccinations for these groups. Furthermore, for the first time this year, every child aged between the ages of two and 11 is eligible for a free nasal spray vaccine together with older children with long-term health conditions.10 Importantly, if you regularly visit hospitals or care homes, or simply want to reduce the risk of getting flu, pop into your local pharmacy and get your flu jab!

Andrew Bryan headshot

Andrew Bryan - Manager, Deloitte Financial Advisory

Andrew is a manager in the Transaction Services (TS) Analytics team, Deloitte Financial Advisory, based in the Leeds office. Using database and visualisation software, Andrew has provided detailed analysis on 50+ TS engagements since joining the firm over 2½ years ago; taking a keen interest in the Healthcare and Life Sciences sector.

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