Coronavirus: what can nuclear physics tell us about stopping the pandemic?

Stephen Chen in Beijing, South China Morning Post

Posted at Sep 22 2020 01:09 PM

* Japanese nuclear physicists say that limiting the spread of the virus could be similar to controlling a thermonuclear reaction
* Models of chain reactions suggest ways authorities can let most people get on with their life without a vaccine

Large-scale testing and timely isolation of the infected people can eliminate the coronavirus pandemic with little or no lockdown measures, according to a new study by a team of Japanese nuclear physicists.

The researchers led by Nagato Yagani from the National Institute for Fusion Science, said that if a person who tested positive was isolated from the rest of the population within eight days of infection, the coronavirus would not be able to spread in a city even as densely packed as Tokyo.

In a non-peer-reviewed paper posted in medRxiv.org on Sunday, the researchers said that limiting the spread of the virus could be similar to controlling a thermonuclear reaction.

Some mathematical equations describing the spread of the virus among people were almost the same as those used in fusion reactor design, according to Yanagi and colleagues.

They said newly infected people were similar to “ash atoms” created by in a nuclear reaction and if they were not removed in time they could destabilise the reactor or even cause an explosion.

“[Tracking and removal] might be the only solution to overcome the pandemic when vaccine is not available,” the paper said.

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The researchers said that many epidemiologists paid little or no attention to the “ash problem” so they created a model based on thermonuclear dynamics, leading to some unexpected results.

For instance, in the model, lockdown measures to restrict movement such as shutting down businesses, workplaces and schools were unnecessary if there was an effective testing programme to identify and isolate a person three to five days after infection for less than 20 days.

Even a looser tracking system that took eight days to identify and isolate infected people would allow more than 70 per cent of the population to go back to normal.

The key to this process was mass testing, the researchers said.

“Only the central and local governments can do wide, repeated and quick Covid-19 testing and quick isolation,” they said in the paper.

The researchers also said testing should be extended to people without symptoms.

“Infected people especially [those] without symptoms should be identified and isolated as soon as possible,” they said.

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Testing technology has improved greatly since the early stages of the outbreak. One US biotech company has developed a machine that can process samples from 5,000 people in two hours with a high degree of accuracy. Some countries such as Israel and China have also adopted citywide testing to identify suspect carriers.

In some countries such as Britain only people with typical coronavirus symptoms such as a cough and fever can get a test. The government is reportedly mulling a plan for another round of lockdowns that would further hobble the British economy, which is grappling with one of its biggest challenges since World War II.

A team of Chinese nuclear engineers have used nuclear chain reaction as an analogy to promote public awareness of pandemic mitigation measures. In a widely circulated article on Chinese social media, they argued that personal actions such as wearing a face mask was like lowering lead rods into a nuclear reactor to stop the chain reaction and a meltdown-like disaster.

“We worried that people wouldn’t understand it because the nuclear physics involved in our explanation is quite complicated,” one of the authors said.

“They don’t, but people buy it because they know what meltdown means.”