The situation with the current outbreak of the novel coronavirus pneumonia (COVID-19) in China is improving. As of March 6, nine provinces across the country have seen zero growth in newly confirmed cases for 14 consecutive days, according to the National Health Commission.

The improvement is considered the "payoff" of government interventions since January 23, including large-scale quarantine, strict travel control, and the lockdown of the epicenter Wuhan in central China's Hubei Province.

What would have happened if China had delayed intervention? 

A prediction made by Chinese respiratory expert Zhong Nanshan and his team in a recent study said the epidemic could have grown to about three times its size if the government had delayed by as little as five days before taking control of the situation.

The study, published in the Journal of Thoracic Disease, uses the susceptible-exposed-infectious-removed (SEIR) model, a mathematical model for epidemic diseases, and artificial intelligence to see the relationship between the number of infected people in China and the start of interventions. 

The researchers input population migration data before and after January 23 and the most updated COVID-19 epidemiological data into the SEIR model to derive the epidemic curve.

The results indicate that with current interventions taken from January 23, the predicted epidemic peak would be in late February and nearing its end by late April. Meanwhile, the total number of infected cases would be 122,122.

If the introduction of interventions had been delayed by five days, the transmission coefficient would have been much greater due to the increase in the average number of contacts with an infected person daily, with the total number of infected cases being three times higher at 351,874.

On the other hand, if the government intervened five days earlier, the total epidemic size could be controlled at 40,991.

The researchers also hypothesized that if the quarantine restriction in Hubei were canceled after the Spring Festival holidays, from January 25 to 31, allowing an influx of new susceptible individuals such as migrants to return, a new epidemic peak in Hubei would have occurred around March 11. 

The study shows how critical the implementation of control measures on January 23 was to reduce the spread of COVID-19 in China. The researchers have suggested that the policy of strict monitoring and early detection remain in place until the end of April.

(Top image via Reuters)