In September, the weather gradually turns cooler, and respiratory diseases will also usher in a season of high incidence. Recently, on social platforms, topics such as “More people are suffering from colds and fevers recently” and “Is the flu coming earlier this year?” have attracted social attention.
On social platforms, more and more people are paying attention to “whether the flu will come early this year” recently. network diagram
In response to the above topic, on September 17, 2026, Zhou Shuqin, deputy director of the emergency department of Shanghai Tenth People’s Hospital, said in an interview with The Paper that in June and July this year, Shanghai did see a wave of rising positive rates of new coronavirus tests, entering July. After August, the number of new crown cases gradually fell back and decreased significantly, but the number of influenza cases began to rise quietly, and the number of infection cases was gradually increasing. “In previous years, influenza often began to gradually increase in October and November. This year, judging from the clinical situation, it is relatively early.”
In view of the recent slight increase in influenza, clinicians call on citizens to receive influenza vaccines in a timely manner. “After the influenza vaccine is vaccinated, it does not take effect immediately. It often takes 2-4 weeks to produce antibodies in the human body. Early vaccination can form effective protection during the period of high influenza incidence.” Zhou Shuqin said.
Hospital: The detection rate of influenza has increased significantly, with influenza A being the main factor
“At present, the positive detection rate of influenza A and B and the number of patients in the hospital have increased significantly compared with before.” Zhou Shuqin said that among patients with simple upper respiratory tract infection symptoms such as runny noses who visit the hospital emergency department, the influenza detection rate has increased significantly, and many of them are accompanied by fever and gastrointestinal symptoms such as diarrhea. Judging from the virus detection situation, the current circulating influenza strains in Shanghai are mainly influenza A, and the number of influenza B detected is relatively small.
Huang Yujuan, director of the emergency department of Shanghai Children’s Hospital, also revealed to reporters on September 17 that among children with flu-like symptoms, the positive detection rate of influenza has also increased. “But it is still in the early stages of the epidemic and has not yet reached the peak of autumn and winter influenza.” According to reports, the current seasonal epidemic is mainly type A H3N2, with superposition of type B Victoria. “Influenza A spreads quickly, mutates easily, and often causes large-scale epidemics; influenza B is more common among children, and many children will develop gastrointestinal symptoms such as vomiting and diarrhea after infection.”
In terms of clinical testing, major hospitals currently use antigen or nucleic acid testing methods for patients with influenza-like symptoms. According to recent influenza testing data from Shanghai Children’s Hospital, from September 7 to 13, among the more than 1,500 cases of influenza-like symptoms that passed antigen testing, the positive rate was 12.52%, and among the more than 3,500 cases that passed nucleic acid testing, the positive rate was 19.19%. “Compared with July and August, the positive detection rate of influenza has increased since September.” Huang Yujuan said.
Huang Yujuan said that in previous years, influenza epidemics were mainly in autumn and winter, but in August this year, the detection rate of influenza A in hospitals was about 8%, and the detection rate of influenza B was about 1%-2%. “Judging from the hospital’s clinical testing data, there is indeed early performance, but the flu dynamics still need to be closely monitored in the future. At present, the hospital is fully equipped with influenza treatment drugs.”
At noon on September 17, 2026, in the emergency department of the Shanghai Children’s Hospital on Luding Road, many parents came for treatment with children with cold symptoms. Photo courtesy of Shanghai Children’s Hospital
After being infected with the flu, people of different ages have different symptoms
According to the latest influenza surveillance data released by the Chinese Center for Disease Control and Prevention in the 36th week of 2026 (August 31-September 6, 2026), the positivity rate of new coronavirus tests is currently on a downward trend, and has generally fallen to a low epidemic level. Influenza activity has increased slightly recently, mainly B (Victoria) and A (H3N2) subtype influenza viruses. The proportion of A (H3N2) subtype has increased. The detection positivity rate in southern provinces is at the mid-epidemic level, and the northern provinces are at the inter-epidemic level. The 15-59 year old case group has the highest detection positivity rate.
Who should pay attention to if you are infected with the flu? Zhou Shuqin pointed out that among the recent cases of influenza virus infection detected in the hospital’s emergency department, many elderly people are mainly concentrated in nursing homes or elderly care institutions, as well as elderly people living at home. “Unlike ordinary infected people, these elderly people often do not have the typical high fever and obvious upper respiratory tract symptoms. When they come to the hospital, they often complain of fatigue, loss of appetite, lethargy, etc. However, after testing, they are found to have influenza virus infection, and some patients have developed severe symptoms such as pneumonia. Most of these elderly patients have basic diseases such as diabetes, hypertension, and cerebral infarction. “
On the morning of September 17, 2026, in the emergency room of Shanghai Tenth People’s Hospital, a patient was being tested for influenza virus. Photo courtesy of Shanghai Tenth People’s Hospital
Zhou Shuqin further said that elderly patients tend to lag behind in seeking medical treatment, which will lead to a long replication time of the influenza virus in the body and a high viral load. The effect of subsequent antiviral treatment will be greatly reduced, the treatment cycle will be greatly extended, and it will take longer for the influenza virus to turn negative, making treatment more difficult.
Guo Yuzhe, the attending physician of the emergency department of Shanghai Children’s Hospital, said that children of different ages show different symptoms after being infected with the influenza virus. The symptoms of babies aged 0 to 3 are often not typical and may not necessarily have obvious coughs. They only show reluctance to eat, frequent crying and shortness of breath. Children aged 3 to 6 will have more prominent fever and cough, and they are not active. Children over 6 years old have symptoms similar to those of adults, with persistent high fever, body aches, and obvious deterioration in mental state. “Everyone can remember a simple way to judge. During the influenza epidemic, if a child suddenly has a high fever, complains of aches all over the body, and is in a bad mental state, he or she should be highly suspicious of influenza and get tested as soon as possible.”
September 17, 2026, outpatient hall of Shanghai Children’s Hospital.
If you have a cold or fever recently, is it still necessary to get a flu shot?
In response to the recent slight increase in influenza activity, the above-mentioned clinicians have called on citizens to receive influenza vaccines in a timely manner.
In response to the misconception of many citizens that “if you have had a cold or fever recently, you do not need to get a flu vaccine,” Zhou Shuqin made it clear that common colds and fevers are not the same as influenza infection. Having cold and fever symptoms does not mean that antibodies to the influenza virus have been produced in the body. Citizens are still at risk of being infected with the influenza virus. It is recommended that these people get the flu vaccine in time after their physical symptoms have completely disappeared and their bodies have recovered for a period of time.
“From a clinical point of view, influenza vaccination can significantly reduce the probability of severe influenza and complications. For people with weak immunity and susceptible people with various basic diseases, vaccination is the most scientific and effective way to prevent influenza and avoid the risk of severe illness.” Zhou Shuqin said.
According to the “Technical Guidelines for Influenza Vaccination in China (2026-2027)” released by the Chinese Center for Disease Control and Prevention on September 2, 2026, the trivalent influenza vaccines on the market in my country in 2026-2027 include trivalent inactivated vaccines and trivalent live attenuated vaccines. Among them, trivalent inactivated vaccines include split vaccines and subunit vaccines, which can be used for people aged 6 months and above, including 0.25mL and 0.5 There are two mL dosage forms; the trivalent live attenuated vaccine is suitable for people aged 3-17 years, with each dose of 0.2 mL.
It is worth noting that the above guidelines are clear: For children aged 6 months and above to under 9 years old, if children in this age group have not received influenza vaccine in the past, when receiving inactivated influenza vaccine for the first time, they should receive 2 doses (select the same vaccine from the same manufacturer for the 2 doses), with an interval of ≥4 weeks; if children in this age group have received influenza vaccine in the past, it is recommended to receive 1 dose this year. If children in this age group are vaccinated with live attenuated influenza virus vaccine, they only need to receive one dose regardless of whether they have received influenza vaccine in the past. For children 9 years and older and adults, only 1 dose is required regardless of previous influenza vaccination.
