A child receives treatment at Beijing Children's Hospital in Beijing, capital of China, Jan. 10, 2018. (Xinhua/Zhang Yuwei)

Chinese netizens expressed concerns over an influenza epidemic in the US that infected 13 million people and killed more than 6,600, while fighting the deadly coronavirus that has killed at least nine back home. 

Analysts noted the US mortality rate looks much higher than China's because of the two countries' different statistical methods. The response came after some net users questioned whether the high death rate shows the ineffective control of flu in the US and how different countries should cooperate effectively to curb the new coronavirus-related disease. 

The flu epidemic in the US eased during the week of January 5-11 but remains active, with an estimated 13-18 million cases of flu illnesses documented since the start of the season, a latest report from the US Centers for Disease Control and Prevention (CDC) said.

The agency also estimates between 6,600 and 17,000 deaths related to influenza since October 1, 2019.

Official Chinese data of flu-caused deaths is much lower, with Chinese CDC data showing that in 2018, there were more than 700,000 cases and 144 deaths. 

But there was an epidemic in early 2019. In January 2019, the number of flu cases in the Chinese mainland reached 608,511, with 143 deaths. In the first five months of 2019 alone, the number of reported cases of influenza  reached 1.77 million, exceeding the total of the past four years. 

Chinese netizens questioned why the flu death rate in China is much lower than that in the US given the overall coverage of flu vaccines in China is less than 2 percent, far lower than the rate of developed countries, including the US. Some doubted the effectiveness of the vaccines. 

"The US flu mortality rate includes cases where flu causes other illnesses to worsen and lead to death, while China only counts people who die directly from flu," an observer who prefers to be anonymous told the Global Times.

The statistical methods used by the Chinese CDC should be revised, as deaths from pneumonia caused by the flu, for example, are not counted, the observer said.

Observers called for an improved statistical approach, and encouraged the public to get an annual flu shot.

An analysis led by Chinese scientists published in The Lancet Public Health in September 2019 found that there were 84,200 to 92,000 flu-related deaths in China each year, accounting for 8.2 percent of all deaths from respiratory diseases.