In late August, the Chinese Center for Disease Control and Prevention released the "Technical Guidelines for Influenza Vaccination in China 2022-2023)" (hereinafter referred to as the Guidelines), launching a new season of influenza vaccination.
The guide states: "This year, some provinces in southern my country have experienced peak epidemics of influenza in summer. This winter and next spring, there may be a superimposed epidemic of new crown and influenza and other respiratory infectious diseases." At present, Qingdao , Hangzhou, Fuzhou and other places The new season's flu vaccine has arrived and citizens can make an appointment.
What is special about this year’s influenza prevention and control situation?
China has established multiple monitoring systems for the spread of influenza viruses. One of the surveillance systems relies on hundreds of sentinel hospitals and laboratories in various provinces to monitor the percentage of influenza-like illness cases (ILI%) among outpatient cases reported by sentinel hospitals to assess the prevalence of influenza. .
It is understood that "influenza-like cases" refer to cases with body temperature ≥38°C, sore throat or cough. The denominator when calculating ILI% is the total number of outpatient and emergency visits, and the numerator is the number of influenza-like cases.
It should be noted that ILI cases with symptoms of fever, sore throat or cough are not necessarily caused by influenza virus infection , but may also be caused by other respiratory pathogens.
Judging from the surveillance data of China’s National Influenza Center, the 33rd week of 2022 (August 15-August 21 Day), the ILI% reported by sentinel hospitals in southern provinces was 3.3%, lower than the previous week's level (3.8%), but higher than the same period in 2019-2021 (3.0%, 2.7% and 2.8%); The ILI% reported by sentinel hospitals in northern provinces was 2.5%, which was lower than the previous week's level (2.6%) and also higher than the levels of the same period in 2019-2021 (2.1%, 1.9% and 2.0%).
Wang Dayan, director of the National Influenza Center of the Institute of Viral Disease Control and Prevention of the Chinese Center for Disease Control and Prevention, said that the positive rate of influenza virus testing in southern provinces has continued to decline in recent weeks. This is caused by the decline in influenza activity in most southern provinces. It can be seen that this summer's The peak has passed, but overall we are still in the flu season and have not yet returned to inter-flu season levels.
"The overall positive rate of influenza virus testing in northern provinces has increased, which is related to the recent increase in the positive rate in some provinces. Recently, both northern and southern provinces in my country are dominated by influenza A (H3N2) subtype influenza viruses." Wang Dayan said.
"Since the outbreak of the new coronavirus, non-pharmaceutical intervention measures such as wearing masks and restricting social distance for a long time have reduced the spread of influenza viruses to a certain extent and reduced the chance of people being infected with influenza, but they will also cause people to have pre-existing immunity to influenza. Decreased influenza susceptibility may increase the risk of future influenza outbreaks," Peng Zhibin, director of the Respiratory Infectious Disease Prevention and Control Office of the Infectious Disease Management Office of the Chinese Center for Disease Control and Prevention, recently said at the "2022 Seasonal Influenza Prevention and Control Strategies Academic Exchange Meeting."
Getting the flu vaccine is the most effective way to prevent the flu.
Why does flu peak in summer?
html Since June, some areas in southern my country have entered a period of high influenza incidence, with the peak of summer influenza appearing. In the 25th week of this year (June 20-June 26), the percentage of outpatient influenza-like illness cases (ILI%) reported by sentinel hospitals in southern provinces once reached 7.5%."The intensity of influenza virus activity in many southern provinces this summer has exceeded the winter peak in recent years." said Guo Shicheng, deputy director of the Institute of Immunization Planning at the Jiangxi Provincial Center for Disease Control and Prevention.
Influenza viruses are divided into four types: A, B, C and D. Among them, influenza C virus appears in scattered form, mainly affects infants and young children, and generally does not cause epidemics. Type D influenza is currently known to only infect cattle and pigs, not humans. The main ones currently infecting humans are H1N1 and H3N2 subtypes of influenza A virus , as well as the Yamagata and Victoria lineages of influenza B viruses.
According to Jiangxi Provincial Disease Control and Prevention, the dominant influenza strain in the province has changed since mid-March this year, from the single prevalent influenza B Vitoria strain in the past two years to the current seasonal influenza A H3N2 subtype. Virus strains, while the H3N2 subtype influenza virus strain has been relatively silent in the past two years, and the immunity level of the population is low. Moreover, this type of influenza strain is prone to triggering a summer epidemic peak, resulting in increased activity of the H3N2 subtype influenza this summer.
In July 1968, an H3N2 influenza subtype broke out in Hong Kong, which later caused a global influenza pandemic; in the summer of 2017, a high-intensity epidemic of H3N2 influenza also occurred in southern provinces.
In fact, influenza may be prevalent in southern my country throughout the year, and is not limited to winter and spring. There is usually a peak of influenza activity in summer.
Influenza virus detection data in southern and northern provinces of my country.
According to surveillance data from China’s National Influenza Center.
Why should you get the flu vaccine?
Hao Lixin, chief physician of the Immunization Program Center of the Chinese Center for Disease Control and Prevention, pointed out that influenza vaccination is the most effective way to prevent influenza and can effectively reduce the disease burden caused by influenza infection, hospitalization, severe illness and death.
In fact, in the eyes of clinicians, the most difficult thing to deal with is not the influenza virus, but infections caused by Streptococcus pneumoniae and other pathogenic bacteria. The harm that influenza brings to people is actually that after it breaks through the body's immune system, it creates more opportunities for infection by other germs. This is a "secondary infection" after a flu infection.
"Viruses set the stage and bacteria perform." If pneumonia caused by this kind of secondary infection occurs, the average cost of treating pneumonia for an adult patient in Beijing will reach 12,148 yuan.
"Actually, we have vaccines to prevent whether it is influenza or Streptococcus pneumoniae infection." said Li Yanming, chief physician of the Department of Respiratory and Critical Care Medicine at Beijing Hospital.
Li Yanming also said that the harm of influenza is not just a simple infection. A study in the United States included cases from the U.S. Influenza Hospitalization Surveillance Network during the two influenza seasons of 2010-2011 and 2017-2018. Among a total of 80,261 hospitalized patients, 11.7% experienced acute cardiovascular events, the most common of which was acute cardiovascular events. Heart failure and acute ischemic heart disease.
"This also reminds us that influenza can also have an impact on cardiovascular health, and influenza causes more cardiovascular events in the elderly." Li Yanming said that for people who already have underlying cardiovascular diseases, they should be actively encouraged to receive influenza vaccines. .
Peng Zhibin introduced that according to the sentinel surveillance data of hospitalized SARI cases in my country from 2011 to 2013, 81%-96% of deaths caused by influenza occurred in people over 65 years old, and 1 in every 3 severe influenza cases Have chronic underlying diseases.
In addition, it has been overlooked that acute influenza infection may have long-term health consequences for vulnerable populations such as the elderly. "For example, after an acute influenza infection, an elderly person who used to be able to walk around freely may become bedridden, begin to suffer from functional impairment, and may even suffer from repeated infections," Li Yanming said.
Therefore, "getting the flu vaccine can be said to not only prevent influenza infection, but also prevent long-term health damage such as functional decline that may occur in the elderly." Li Yanming said.
Why did flu vaccination rates drop so sharply last year?
Since influenza viruses are prone to mutation, and the production cycle of the world's mainstream chicken embryo-based vaccines is about 4-5 months, the World Health Organization will predict based on global influenza surveillance data in February and September every year. Release of recommended strains for influenza vaccine in the Northern and Southern Hemispheres.
Therefore, the flu vaccine strains may be different from year to year. It is reported that the northern hemisphere influenza vaccine components for the 2022-2023 influenza season have changed the A (H3N2) subtype and B Victoria strains compared with the previous epidemic season.
my country's influenza vaccination rate is already extremely low, but during the 2021-2022 influenza season under the normalized prevention and control of the new crown epidemic, the influenza vaccination rate has dropped further.
“The current situation of influenza vaccination in my country is far from ideal."Peng Zhibin, associate researcher at the Infectious Disease Management Division of the Chinese Center for Disease Control and Prevention, disclosed at the 2022 National Vaccine and Health Conference that in the 2020-2021 influenza epidemic season, my country's influenza vaccination rate was 3.34%. In the 2021-2022 influenza epidemic season, the vaccination rate Only 2.46%, down 0.88% year over year
In comparison, the United States in 2020. -The influenza vaccination rate in 2021 is about 52.1%, and the influenza vaccination rate in Canada from 2020 to 2021 is about 40%.
Influenza vaccine has not yet been included in my country's national immunization plan. In most areas, influenza vaccination is required voluntarily and at one's own expense. Vaccine. According to a survey on influenza vaccination among the entire population in 6 provinces in my country, the answer is When asked why not get a flu vaccine, 36.3% of people think that "I am in good health and are not afraid of the flu", 31.1% of people "don't know about the flu vaccine", and 7.7% of people think that "it is inconvenient to get vaccinated". These reasons ranked first among people. The top three reasons for not getting the flu vaccine.
Some measures have been taken at the local level to promote the vaccination and popularization of flu vaccines. During the 2022 influenza epidemic season, 256 counties and districts implemented free influenza vaccination policies for specific key groups such as preschool children, primary and secondary school students, the elderly, and medical personnel. Among them, 226 counties and districts provided free vaccination for the elderly. There are 101 counties and districts that provide free vaccination to medical personnel and other key groups.
Free vaccination can be improved to a certain extent. Influenza vaccine vaccination rate, in the 2021-2022 influenza epidemic season, among various target groups such as the elderly and primary and secondary school students who implement the free vaccination policy, the vaccination rate is the lowest at 26.1%
In addition, in the 2021-2022 influenza epidemic season, A total of 135 counties and districts in my country have implemented the influenza vaccine medical insurance reimbursement policy, covering approximately 31.07 million people, an increase from the previous year. The degree increased by 0.11 times. The medical insurance reimbursement ratio ranges from 5% to 100%, covering a wide range of people, including 21 counties and districts that achieve full population coverage.
It is worth noting that the new version of the "Guidelines" also follows the recommendations of the World Health Organization. As well as relevant evidence, it is clear that people aged 18 and above can receive the inactivated influenza vaccine and the new crown vaccine at the same time. However, for those who receive attenuated influenza vaccine and minors under the age of 18, due to the current lack of evidence for simultaneous vaccination with new coronavirus vaccine , the relevant national recommendations are still followed and the interval between vaccination with the new coronavirus vaccine should be greater than 14 days
Chinese medical personnel. Influenza vaccination rate urgently needs to be improved
Medical workers are a high-risk group susceptible to influenza. The incidence of influenza among medical workers who have not been vaccinated against influenza is 3.4 times that of healthy adults. At the same time, infection of influenza viruses among medical workers will also increase the risk of infection among patients. Among 194 countries, 96 countries have set medical personnel as a priority group for influenza vaccination, and some countries have set medical personnel as a compulsory vaccination group.
"Technical Guidelines for Influenza Vaccine Vaccination in China (2022-2023)" also lists medical personnel, including clinical treatment personnel, public health personnel, health and quarantine personnel, etc. as priority groups for vaccination.
Other priority groups listed in the "Guide" for vaccination include participants in large-scale events and support personnel; vulnerable groups and employees in nursing homes, long-term care institutions, welfare homes and other crowded places; and groups in key places, such as child care institutions. , teachers and students in primary and secondary schools, detainees and staff in prisons and institutions, etc.; other high-risk groups for influenza, including homebound elderly people aged 60 and above, children aged 6 months to 5 years old, patients with chronic diseases, and those under 6 months old Family members and caregivers of the baby and pregnant women.
Peng Zhibin introduced that compared with other countries in the world, the overall influenza vaccination rate among Chinese medical staff is low, which has been around 10% in recent years. In the 2020-2021 influenza season, the vaccination rate of medical personnel in the United States is approximately 75.9%, and the vaccination rate of medical personnel in the United Kingdom is 76.8%. There are also some areas in my country with higher vaccination rates for medical staff. For example, the vaccination rate for medical staff at the social health center in Nanshan District, Shenzhen City from 2015 to 2019 was 77.6%. According to third-party surveys, the free vaccination policy can effectively increase the influenza vaccination rate of medical staff.
Why do medical staff’s attitudes towards influenza vaccines deserve attention? Behind this actually involves the overall systemic issue of influenza prevention and control."If medical staff in grassroots communities receive relevant training, they can increase the influenza vaccine vaccination rate among the elderly in a community." Li Yanming said.
There was a study that compared influenza vaccination among the elderly in two streets: In the street that received the intervention, the influenza vaccination rate among the elderly reached 19%, while the vaccination rate among the elderly in the street that was not intervened was only 0.4%. %. Among the elderly who have been vaccinated, 98% said the main reason for vaccination was "recommendation by medical staff."
Interview and writing: Trainee reporter Zhao Linxuan Nandu reporter Wu Bin From Beijing
Nandu cartography: Li Bei
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