Coronavirus in maps and charts: Tracking the outbreak around the world

Following data through maps and graphs can help public understand how spread of Covid-19 will impact their daily lives and influence government responses, Dr Joshua Moon says

When the first coronavirus cases were diagnosed in the Chinese city of Wuhan in December and news of an outbreak began to trickle out of the country, few could have predicted the coming pandemic.

More than 5 million Covid-19 cases have since been identified around the world and the virus has killed more than 323,000 people.

The World Health Organisation has declared the outbreak a pandemic and countries have told their citizens to stay at home to reduce the spread of the infection.

In the UK, more than 250,000 cases and 35,000 deaths have been recorded. Meanwhile, in the US there have been more than 1.5 million cases and more than 91,000 deaths from the virus, according to data from the Johns Hopkins University.

The Independent has been mapping the spread of coronavirus around the world around publishing updated daily figures on the extent of the outbreak.

Governments around the world have been publishing daily tallies, including the death toll, the number of people who have tested positive and the total numbers tested.

Such data has proven extremely useful in helping to track the development of the outbreak, according to Dr Joshua Moon, a Research Fellow in Sustainability Research Methods in the Science Policy Research Unit (SPRU) at the University of Sussex Business School.

“I’m not entirely sure the importance of that [data] can be overstated,” Dr Moon told The Independent. ”When it comes to epidemic response, data and the ability to identify cases is a central factor of stemming transmission.”

Dr Moon said data has been used to identify who has been infected, trace people they may have come into contact with and then isolate them from the general public to try and slow down the transmission of the disease.

“In terms of this outbreak, one thing we can say is that the availability of data and the ability to transmit it across the world is far and beyond much better than what we saw in 2003, but has demonstrated that it’s come on leaps and bounds since previous outbreaks,” he said, referring to the SARS outbreak.

By visualising data in maps and graphs, “there has been an ability to track where things are and where they’re coming from,” Dr Moon said, giving the example of a visualisation showing how most cases in Africa were coming from Europe rather than China, the epicentre of the outbreak. “We’ve moved past the exporting of cases from China to this European locus of spread across the world,” he added.

“In terms of caseloads, we’re definitely seeing a switch to cases being exported not from Asia but from Europe and the US. So it’s important to be able to shift your understanding of how a disease is transmitting if you have a real-time picture of the data.”

Following the data through maps and graphs can help the public understand how the spread of the virus will impact their daily lives and how it will influence the government’s future responses, Dr Moon said.

He cautioned that keeping up with daily counts is “likely to not be overly useful, particularly given the fluctuations in the case and death counts that often happen” but said looking for longer-term trends, such as when the curve in new case numbers begins to level off would be more useful.

“For example, the UK had a huge spike on Tuesday 7 April but that’s likely due to some undercounting over the weekend,” he said. “So really it’s more about looking for those long-term trends and seeing whether the outbreak is still on the exponential part where it’s increasing every day, or are we starting to see a tapering off effect.”

Provided by INK C-19 symptom map (users report the health status of their household: green for healthy, yellow for suspected symptoms, red for actual symptoms and blue for past symptoms)

The moment to look out for would be when the curve starts to level off, he said, “when we’ve had a few days in a row ... particularly if you start getting an entire week where case numbers are starting to either remain constant or starting to decrease.

“Those are the kinds of things that we should be looking for because that’s the moment when there’s going to be a consideration of starting to ease some of these lockdown restrictions.”

He added: “The numbers are unlikely to impact everybody’s daily lives, it’s a question of facing what’s in front of you more than anything else.”

One potential issue with the data is that countries have been testing for the virus in different ways, making it difficult to compare the number of cases between them. “Even data coming out of China is demonstrating how much is missed by the real-time testing and the ability to only test certain segments of the population.”

Additionally, countries recorded their first cases of the virus at different times, putting them on different time scales in terms of how the outbreak will peak.

But Dr Moon said comparing death rates is easier, though still slightly complicated by the way they are recorded, as there is “less likely to be a drastic underestimation of deaths”.

Dr Moon warned that some graphs published online and in the media have misinterpreted data and cautioned the public to look out for those which feature large jumps in steps representing case numbers on the y-axis of the chart, or those with log scales, where each step is a multiplication of cases rather than an addition.

“Those are useful for responders to be looking at if they’re saying on a log scale these things are changing either quite slowly or rapidly,” he said. “But in terms of communicating to the layman, they have a possible effect of either making things look much worse or much better than they are without necessarily fully communicating the uncertainty or the real dynamics that are going on, and are very easy to misinterpret.”