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Normal text size Larger text size Very large text size Australians have watched the spread of the global coronavirus pandemic with a sense of foreboding. The Johns Hopkins University heatmap, which quickly became the go-to site to monitor the virus, has become an increasingly ominous image as its pulsing red dots have spread and grown like fire embers. We've watched as the virus erupted in Wuhan and threatened to engulf China. The dots have proliferated across continents – Asia, Europe, the Americas. Then COVID-19 reached Australia at the end of January. Progress of the disease has been captured in the visual snapshots with charts that are updated several times a day. Right now, the charts below give an up-to-date and cohesive view of COVID-19 across the country. Eventually, they will show something more than the progress of the virus. They will be a visual illustration of our response. They will show the effectiveness of the actions and decisions of governments, health authorities and citizens.


Above, we can see the total number of COVID-19 cases in Australia over time. It made slow progress throughout February and began to surge in March. It started with 15 travellers who had been to China; all of those cases were specifically linked to Wuhan. At the end of February, passengers on the Diamond Princess cruise ship – which had been quarantined in Japan – were allowed to disembark, bringing another 10 cases home. This chart, above, was most useful towards the start of the pandemic in Australia. It showed how COVID-19 cases surged in March. (They were primarily driven by travellers importing the virus after catching it overseas. More on that later). But it is less useful as the pandemic continues because it does not tell us whether new confirmed cases are speeding up or slowing down. This chart, above, shows the number of new confirmed cases in Australia each day. (Numbers are progressively updated throughout the day as states and territories announce new cases. Therefore the final day in this chart is incomplete until all announcements have been made.)


It tells us more than the first about the behaviour of the virus in Australia today. Coronavirus was spreading rapidly during March with case numbers jumping every day. In April, although we are still adding significant numbers of new cases each day, growth has slowed as the effects of travel restrictions, social distancing and shutdowns have taken effect. Above is a breakdown of total cases across states and territories. NSW clearly accounts for a significant part of Australia's growth in COVID-19 cases, however Victoria and Queensland saw sharp up-ticks also. (Depending on the time of day you're looking at this chart, you may see curves flatline at the end. That could be because there were no new cases that day, but it's probably because the state was yet to announce them. Best to check back later.) Like the first graph, the chart above shows linear curves that represent the total number of cases over time. You cannot use either of them – especially the trajectories – to gauge growth or compare Australia to other countries. To do that, we need to look at the next graph. This chart, above, really starts to tell a story. The log scale (as opposed to linear scale) shows the rate of change over time. Each of these lines represents a country's confirmed number of coronavirus cases since their 100th case. Roll over or tap on these lines to see the country they represent or type in a country in the box at the top to examine just its data. Why did we start at case number 100? Because we want to compare countries at the same moment in time in relation to the virus.


This chart doesn't just tell us about the progression of a virus; it tells us about a country's response. The line tracking across the top is China. You can see the virus there spiralled out of control as cases rose exponentially. Then the country clawed back control through extreme measures including locking down hundreds of millions of people. Loading South Korea's curve has a similar progression, also starting to flatten. The country arrested its exponential growth primarily through expansive testing and targeted isolation and quarantines. European countries such as Italy and Spain are on that exponential rise. The hope is that their current measures – nationwide lockdowns – will start to flatten those curves. Australia is the green line rising steeply, with only Japan (mauve line) and Singapore under it. What does this chart tell us about Australia's response? It is tricky to see what's happening in the bottom left corner (so rollover or use the search box), but one thing it does show is Australia and Japan were roughly on par until about four days after their 100th cases. After that, Japan's curve shallowed while Australia's continued to rise. Japanese policies of note were the closure of schools and the suspension of large-scale gatherings at the end of February.


Before we lose ourselves in all those curves, it is critical to understand the different ways these people caught coronavirus. This chart, above, shows us the underlying reason for COVID-19 infections in NSW. For the best part of March, Australia's health authorities were at pains to point out that while the increasing number of cases looked concerning, the vast majority of them were people who caught it overseas or by a transmission that may have been local but was known and directly linked to that overseas travel. For example: a man travelled to Italy, caught coronavirus there, came home and gave it to his wife. Loading There is no doubt COVID-19 entered Australia in people who caught it overseas. While Australians were fearful of events unfolding in China, Iran and Italy, many people who tested positive after travelling had been to the United States, where the numbers quietly crept up. The restrictions on travel, such as mandatory quarantines and blocking non-citizens and non-residents, were designed to stop this flow. The virus has an incubation period of up to 14 days, which means the full effects of these policies are yet to be seen. A surge in infections on cruise ships meant these numbers continued to climb in late March. Other people in NSW were infected by what's called a known local transmission, which means contact tracers were able to establish the person and place from which the virus was caught. The biggest concern is the increasing number of unknown local transmissions in NSW, also referred to as community transmissions. In these cases, contact tracers have not been able to work out the source of the infection. With these types of cases on the rise, measures such as social distancing and shutdowns are designed to stop this spread.


This chart shows the total number of open cases, recoveries and deaths in Australia. Note that one figure of a person here doesn't represent one case: the figures are proportionate to the number of cases. Finally, our virus tracker, below, provides a global view of cases in real-time. It is linked to data from the Centre for Systems Science and Engineering at Johns Hopkins University in Baltimore, and was first shared publicly on January 22. The tracker shows confirmed COVID-19 cases, deaths and recoveries at a glance for all affected countries. Juliette O'Brien is the creator of covid19data.com.au, a website tracking COVID-19 in Australia. – with Nigel Gladstone Sign up to our Coronavirus Update newsletter Get our Coronavirus Update newsletter for the day's crucial developments at a glance, the numbers you need to know and what our readers are saying. Sign up to The Sydney Morning Herald's newsletter here and The Age's here.