Explained: Why follow social distancing, in data
With public gatherings restricted worldwide, the question is how such moves affect COVID-2019 trends. A look at how the outbreak curve shapes, with or without social distancing, and why a flatter curve helps
With milder symptoms, the infected are more likely to be active and still spreading the virus.
Over the last two days, a number of states in India have enforced measures aimed at reducing public gatherings. This is called “social distancing”. With 100,000 reported cases of COVID-19 in 100 countries, starting with the outbreak in Wuhan in China 10 weeks ago, researchers have analysed trends in the spread have made a case for social distancing as a mitigation and containment strategy.
How does social distancing work?
To stem the speed of the coronavirus spread so that healthcare systems can handle the influx, experts are advising people to avoid mass gatherings. Offices, schools, concerts, conferences, sports events, weddings, and the like have been shut or cancelled around the world, including in a number of Indian states. An advisory by the US Centers for Disease Control recommends social distancing measures such as: reducing the frequency of large gatherings and limiting the number of attendees; limiting inter-school interactions; and considering distance or e-learning in some settings (which could be interpreted as serving the same purpose as working from home).
What is the objective of such restrictions?
Compared to deadlier diseases such as bird flu, or H5N1, coronavirus is not as fatal —which ironically also makes it more difficult to contain. With milder symptoms, the infected are more likely to be active and still spreading the virus. For example, more than half the cases aboard a cruise ship that has docked in California did not exhibit any symptoms.
In a briefing on March 11, World Health Organization (WHO) officials said, “Action must be taken to prevent transmission at the community level to reduce the epidemic to manageable clusters.” The main question for governments is how do you reduce the impact of the virus by flattening the trajectory of cases from a sharp bell curve to an elongated speed-bump-like curve. This is being called “flattening the curve”. How does ‘flattening the curve’ help?
A slow growth in patients can be handled by healthcare systems much more than a sharp rise. In effect, the goal is to postpone the spread over time.
As a report in The Atlantic stated: “A pandemic is like a slow-motion hurricane that will hit the entire world. If the same amount of rain and wind is to hit us in any scenario, better to have it come over the course of a day than an hour. People will suffer either way, but spreading the damage out will allow as many people as possible to care for one another.”
Limiting community transmission is the best way to flatten the curve.
What was the curve like in China?
The numbers show that the virus spread within Hubei exponentially but plateaued in other provinces. Just as Chinese provinces outside of Hubei effectively stemmed the spread in February, three other countries —South Korea, Italy, and Iran — were not able to flatten the curve.
On December 30, active case finding began in Wuhan. Around January 21, the number of cases started to jump intensely to roughly 550 infections and 17 deaths. Wuhan city’s lockdown was two days later. The next day, another 15 Chinese cities were shut down, eventually cordoning off 100 million people. In Chinese regions outside Hubei, new cases plateaued from February 9 onwards. All of these regions could have exploded exponentially, but tapered off.
Where else did the curve grow and eventually flatten?
As reported in the March 11 WHO briefing, 93% of cases are from four countries, making it “an uneven epidemic at the global level.” Countries are using varying testing and diagnostic systems, making comparisons tentative.
It is clear, however, that new cases began to grow in South Korea, Italy, Iran by the end of February, surpassing all Chinese regions other than Hubei.
On the other hand, countries close to China — Japan, Taiwan, Singapore, Thailand — as well as Hong Kong saw growth in case numbers plateau. Some say it’s because many of these countries learnt from the 2003 SARS epidemic. The WHO singled out Singapore as a “good example of an all-of-government approach.”
South Korea is an outlier. Experts say the country contained the virus within the first 30 patients, but on February 17 the 31st one spread it to thousands of people and symptoms showed themselves too late for authorities to check the outbreak. By now, South Korea’s case growth has shown decline, while Italy and Iran have quickly surpassed it.
Why are Europe and the United States now concerned?
The growth in European countries and the United States since the beginning of March resembles the initial curves of Italy and Hubei during their respective growth phases, leaving officials wondering if they will follow the same trajectory. Experts say that if countries take measures similar to Singapore and Taiwan, they may be able to avoid that fate.
New cases have shot up in France, Germany, Spain, US, Switzerland, and the UK. Between March 5 and 6, there were a number of countries that doubled their case numbers. In order of highest daily growth rate, they were Belgium, Switzerland, the UAE, Netherlands, France, Austria, Malaysia, Sweden, Greece, USA, Spain, UK and Norway.
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