Zeng Guang Photo: Courtesy of Zeng

A top Chinese epidemiologist has warned against the high possibility of a "twindemic" scenario of COVID-19 and influenza in the upcoming winter and the spring and urged the public to be vaccinated against both.

Influenza has experienced an unusual peak period since this summer, which means it came earlier than usual, and there are two variants. Thus, the risk of a combination of influenza and COVID-19 this winter and next spring is higher, Zeng Guang, former chief epidemiologist of the Chinese Center for Disease Control and Prevention (China's CDC), said on Sunday.

This summer, southern China saw an increase of flu cases after its traditional peak season from April to June and the northern parts of China had more cases after July, although January and February are normally the peak seasons, Zeng explained.

One reason for this situation is that the Omicron variant of COVID-19 is making some people less vigilant. Chinese people's previous high vigilance and preventive measures against COVID-19 such as wearing masks have effectively restrained both the flu and COVID-19. 

To deal with a possible "twindemic", Zeng, quoted by the Health Times affiliated with the People's Daily, called for dual vaccinations, especially for vulnerable groups including students, elderly people who usually have chronic diseases, and pregnant women.

Zeng's warning coincided with the start of flu vaccinations in multiple Chinese cities.  

Beijing will provide free flu vaccines in three batches from September 13 through the end of November. Those over 60 are in the first batch, while students from primary schools, high schools and secondary vocational schools are in the second batch. Residents can pay by themselves for vaccination until of the end of February in 2023.

Mass flu vaccinations were rolled out as early as June in some parts of South China's Guangdong, Southwest China's Sichuan and East China's Fujian, which had surging flu cases in the summer. 

A continuous call for receiving influenza vaccines is needed, Zhuang Shilihe, a Guangzhou-based medical expert who closely follows public health issues, told the Global Times on Sunday. He said that in the past decade, the flu vaccination rate had not exceeded 5 percent, and many people wrongly think of the flu as just like a cold.

"I booked a vaccine against flu for my 3-year-old son and my entire family after learning this winter would see a high prevalence. I'm quite worried, but most people around me are not," Xiaojing, a Beijing resident, told the Global Times.

According to the National Health Commission (NHC), 1.27 billion Chinese people have taken COVID-19 vaccine, but the rate for flu is much less. The Chinese CDC said in August that the vaccination rate in the flu high-occurrence season from 2021 to 2022 was only about 2.46 percent.

To address a potential twindemic, Zeng suggested a simultaneous flu and COVID-19 shot. 

The expert said vaccines of the two being received at the same time is safe for adults above 18, suggesting a 14-day interval for people under 18 between their influenza and COVID-19 shots. In August, the Chinese CDC released technical guidelines for influenza vaccination for 2022 to 2023, allowing people above the age of 18 to receive both inactivated influenza vaccine and COVID-19 vaccine at the same time.

"It's better to get the flu vaccine two weeks ahead of the high-occurrence seasons. People in the north part of China can get vaccinated from late October to mid-November," Zeng noted.

Some believed the risk of a twindemic should not be exaggerated. Shao Yiming, a leading virologist and immunologist at the China CDC, told the Global Times in earlier interview that China has about three years of experience in handling this risk, and there is an effective mechanism to address the risk.

Data compiled by the NHC on Sunday showed the COVID-19 situation in China has been grave since August, with over 1,000 cases being reported in a dozen provinces and regions on Saturday.