Shoppers, some wearing face-masks, walk along Oxford Street in central London on Dec 4, 2021, as compulsory mask wearing in shops has been reintroduced in England as fears rise over the Omicron variant of COVID-19. (DANIEL LEAL / AFP)

The necessity to err on the side of caution should be the lesson the world has learned from the repeated waves of infections caused by the different variants of the novel coronavirus.

It is not yet known if the new variant Omicron causes more virulent disease than the past variants. But what is known is that Omicron is extremely contagious. "Omicron is spreading at a rate we have not seen with any previous variant," World Health Organization Director-General Tedros Adhanom Ghebreyesus said during a COVID-19 update in Geneva on Tuesday.

Omicron cases have been reported in more than 70 countries and it might have already spread to more countries, although cases have not been identified.

On Wednesday alone, the number of new cases detected worldwide reached more than 700,000. Jenny Harries, head of the UK Health Security Agency, said that Omicron is displaying a staggering growth rate compared with previous variants.

"Even if Omicron does cause less severe disease, the sheer number of cases could once again overwhelm unprepared health systems," Tedros said.

The WHO's COVID-19 technical lead, Maria van Kerkhove, warned that the risks of the Omicron strain should not be taken lightly or dismissed. "We have to be really careful that there isn't a narrative out there that it's just a mild disease."

She said that people infected with Omicron have shown the full spectrum of COVID-19, from asymptomatic infection to mild disease, all the way to severe disease and deaths.

With the arrival of Omicron, governments everywhere must bite the bullet and enforce prevention and control measures to get control of the virus, no matter how unpopular such moves may be with the public.

While the vaccines that are being administered are important, they cannot be relied on alone to fight the virus. It is not yet known when effective medicines will be developed to prevent humans from being infected and to effectively fight against the virus－or if that is even possible.

The WHO officials emphasized the importance of people wearing masks, observing social distancing and washing their hands.

That is exactly what China has been mandating. That is how the country has generally kept the virus under control and guaranteed the normal operation of its economy.

The Omicron variant is another wakeup call that it is just wishful thinking to assume that humans can live with the virus without implementing strict prevention and control measures.

The global picture would be much rosier had all countries followed China's example in the fight against the virus.