To facilitate this requirement, airports and ports of entry should be limited to Beijing, Shanghai, Tianjin and Guangzhou, with isolation facilities nearby ready to be used.

This may sound draconian and will cause disruption not only to tourism but to all commercial activities, including international trade and cross-border investment. However, this is the only safe and sure way to prevent a recurrence of a Covid-2019 epidemic in China. China will switch from being a “blocked country” to a “blocking country”.

One might ask: if every country adopts such a policy to protect its citizens, would that mean the end of globalisation? I believe it wouldn’t be the end, but the beginning of a safer and more stable form of globalisation that is less susceptible to potential disruption.

Years ago, I would travel not only with a passport, but also with a small yellow booklet which recorded all my vaccinations and inoculations, which would be examined before entry to another country. I would need vaccinations against smallpox, cholera and other diseases, and occasionally a shot of immunity-boosting gamma globulin.

This epidemic has taught us the necessity of reinstating some form of these requirements if we are to continue to be able to travel freely internationally. The destination country of a traveller would need to know his or her recent health, including vaccinations and travel history.

It is actually quite straightforward for an international authority like the World Health Organisation to maintain such a record in digital form, in real time, so that it is readily available for inspection whenever a traveller crosses a border.

Coronavirus: a chance for China to boost its world standing?

For example, if and when a vaccine becomes available for Covid-2019, it should be required for those who wish to be exempted from the mandatory quarantine requirement. This should also apply to other transmissible diseases and viruses in future.

A traveller without an acceptable WHO record would have to satisfy whatever other requirements the destination country may impose, including possibly a lengthy quarantine period. If such a system could be implemented globally, then all citizens would be reassured that foreign visitors did not pose a health threat.

However, simply controlling borders is not enough. It is extremely important to prevent domestic transmission of diseases and viruses by unidentified local infected patients.

In time, perhaps most doors can be sensor-operated and lifts can be voice-activated, so that indirect physical contact between an infected person and others can be minimised. The transmission of the virus will stop if everyone takes the proper precautions for his or her own protection.

But even without these geopolitical tensions, the epidemic shows that second sources are still indispensable. It is crucial for economies to have at least one second source for any link in any supply chain. This can be costly, but it also provides insurance against unexpected contingencies, such as an epidemic, a natural disaster or even a war.

It also prevents a supplier from overexploiting its monopoly position. Not having a second source can sometimes prove to be even more costly, as when production is halted because of the lack of a critical component.

Of course, a country can try to be totally self-sufficient, as the former Soviet Union and China did at one time, but it would be extremely costly.

In future, we can expect to see “diversified globalisation”, so that no single country is completely dependent on another as a sole source of supply. There will be a second source for everything. In the long run, the world will be better off having two or more competing suppliers for every type of goods or service.

Lawrence J. Lau is Ralph and Claire Landau Professor of Economics, the Chinese University of Hong Kong, and Kwoh-Ting Li Professor in Economic Development, Emeritus, Stanford University