More than 100 people were infected by the highly contagious novel coronavirus by December 31 at the outbreak epicentre Wuhan, three weeks before it was officially declared to be transmissible between humans and the city was put under a lockdown, it has emerged.

A study – the largest so far on the outbreak — conducted by the Chinese Centre for Disease Control and Prevention (CDC) also say over 6,000 might have been infected by January 20 in China besides across the worst-hit Hubei province and its capital city, Wuhan.

Data accessed and analysed by the CDC shows that 15 among the 104 infected in December, 102 among the 653 infected between January 1 and 10 and 310 among the 5,417 infected between January 11 and January 20 later died of the virus.

The official death toll on January 20 was 3 and the number of infected was 225.

Titled “Analysis of Epidemiological Characteristics of New Coronavirus Pneumonia”, the CDC accessed data on more than 72000 covid-19 cases reported until February 11.

The Hindustan Times reported on the study on Monday but the full import of the largest covid-19 study is emerging only now.

Until early on Wednesday, the death toll from the outbreak in China stood at 2004 and 74,185 were reported to be infected with the pathogen; 136 new deaths were reported on Tuesday.

Hundreds of infections and at least four deaths have been reported from at least 25 countries.

The largest study by the CDC – China’s top institute leading the fights against the contagion — on the outbreak suggests that authorities did nothing to stop the epidemic from spreading within China and beyond despite knowing about it.

In a statistical table published in the study, the CDC says 104 people were infected with the pathogen by December 31 and 15 later died.

The CDC study indicates that health authorities at the provincial level were well aware of the disease and its virulence but chose not to take steps to contain the spread.

President Xi Jinping had, in fact, held a meeting on January 7 on the coronavirus cases – again clearly showing that topmost leadership of the ruling Communist Party of China (CPC) had relevant information.

The WHO was notified on January 3.

Here’s what the CDC says in its abstract for the study: “The covid-19 spread outward from Hubei sometime after December 2019 and by February 11, 2020, 386 counties across all 31 provinces were affected.”

“The epidemic curve of onset of symptoms peaked in January 23-26, then began to decline leading up to February 11.”

“The covid-19 epidemic has spread very quickly. It only took 30 days to expand from Hubei to the rest of Mainland China. With many people returning from a long holiday, China needs to prepare for the possible rebound of the epidemic,” the study said.

The paper did a retrospective analysis of 44,672 confirmed patients and divided the outbreak of the deadly disease into five different phases: The one before December 31, 2019, January 1 to 10, January 11 to 20, January 21 to 31 and February 1 to 11.

“Here, we report results of a descriptive, exploratory analysis of all cases diagnosed as of February 11, 2020. Methods: All covid-19 cases reported through February 11, 2020, were extracted from China’s Infectious Disease Information System,” the study said.

“The cases that occurred in December 2019 may be a small-scale exposure transmission mode; in January 2020, it may be a diffusion transmission mode. The time trend of this outbreak is consistent with the previous survey conclusion that the south China seafood market in Wuhan may have wild animal trading, allowing the new coronavirus to spread from a still unknown wildlife to humans, and then spread from person to person,” the study added.

Quoting the study, even state-controlled media has raised questions about China’s response to the initial outbreak of the disease.

“From January 11 to 20, there were 5,417 new infections in total, which was also in line with information provided by local hospitals in Wuhan to the Global Times, indicating that even before Zhong Nanshan, a top medical advisor warned the disease could be transmitted human to human on January 20, many hospitals in Wuhan had received a large number of patients with fever from unknown causes.

However, those concerns remained at the local hospital level, with no further prevention and control measures taken by local authorities,” the tabloid Global Times said in a report.

A lid was kept on the gradually spreading outbreak despite efforts by local doctors like Li Wenliang attempting to share information about it.

Li was reprimanded and harassed for talking about the disease on social media platforms.

Li died from the infection earlier this month, leading to an outpouring of grief and anger online.

Earlier this month, the CPC’s central committee sacked Jiang Chaoliang, the CPC party chief in Hubei province, and replaced him with the Shanghai mayor, Ying Yong.

The CPC chief in Wuhan, Ma Guoqiang, was fired as well, replaced by the party chief of Jinan city in Shandong province, Wang Zhonglin.