Source 丨21 Healthnews21 original work
Author 丨 Wei laughs
Editor 丨Xu Xu
Image source 丨 Figureworm
In the past two years, due to the "squeeze" of the new crown epidemic, the previous seasonal outbreak of influenza once disappeared. However, at the beginning of the new year, under the influence of the "double La Niña" incident, accompanied by frequent cold air activity, influenza made a comeback.
Since late October 2021, the lowest temperatures in many municipalities and provincial capitals have hit a new low in the same period in a decade. With the sudden "cooling", the vast area of China has also entered a period of high incidence of influenza. Influenza surveillance data from the Chinese Center for Disease Control and Prevention shows that the recent positive rate of influenza tests in northern and southern provinces has shown an upward trend, which is significantly higher than the same period last year.
Previously, CCTV reports also showed that since 2021, the global influenza activity has increased, especially since September 2021, some cities in southern China have shown a clear upward trend. The incidence of influenza in children is relatively high, 3 of the 10 children in the influenza season may be infected with influenza, and the incidence of influenza in children can even be as high as 50% during the high incidence season, and the report reminds that attention should be paid to the serious risk of severe illness caused by the superposition of children's influenza and the new crown, and pay attention to the problem of antiviral safety medication of children's influenza.
The active influenza has also led to an increasing number of confirmed cases of influenza in China. For example, on January 9, the relevant personnel of a hospital in Changsha said that more than 500 children were treated in 5 days; on January 7, the relevant personnel of a hospital in Shijiazhuang said that the number of influenza had increased significantly, and the proportion of children accounted for a considerable proportion.
"My son just started kindergarten this year, and many students in the class have asked for leave because of symptoms such as fever, cough, runny nose, vomiting, diarrhea and so on. My child was still in good spirits yesterday, and today he began to have symptoms of fever, cough and runny nose, and he had to take time off to rest at home. Wang Li (pseudonym) from Shanghai said in an interview with the 21st Century Business Herald.
While many people are still paying the most attention to the Omicron outbreak, the flu is already poised. The high flu season is coming, are you ready?
Influenza is not a "minor illness" or can be fatal
Influenza is an acute respiratory infectious disease caused by influenza viruses. It is mainly transmitted by droplets of respiratory secretions, but also through direct or indirect contact with mucous membranes such as the mouth, nasal cavity, and eyes. It is popular and high in the winter and spring of our country every year.
Influenza viruses belong to the family orthogonal myxovirus and are single-stranded, negative-stranded, segmented RNA viruses. According to viral nuclear proteins and matrix proteins, it is divided into four types: A, B, C, and D (or A, B, C, D). Human influenza is mainly caused by influenza A virus and influenza B virus.
As a rapidly spreading infectious disease, influenza is the most harmful to high-risk groups such as infants, students in school, the elderly over 60 years old, patients with chronic diseases, medical workers and pregnant women, and the risk of outbreaks, serious complications and death is high. Influenza outbreaks are prone to outbreaks in crowded areas such as nursing homes, primary and secondary schools and childcare facilities.
According to WHO data, influenza in the world causes up to 650,000 deaths every year, 1 person dies from influenza every 48 seconds, 1 child dies from influenza-related diseases every 5 minutes, and 1 in 5 health care workers becomes ill from influenza.
In particular, severe influenza can present with a variety of life-threatening complications such as viral pneumonia, secondary bacterial pneumonia, acute respiratory distress syndrome, shock, and diffuse intravascular coagulation.
Professor Zeng Mei, chief physician of the Department of Infection and Infectious Diseases of the Children's Hospital affiliated to Fudan University for many years, said in an interview with the 21st Century Business Herald reporter that more than 10 cases of critical influenza patients are encountered every year. Some children will die of severe pneumonia after the flu; some children will die of meningitis after the flu, and some children will suddenly convulse and fall into a coma the day after the flu, no matter how to save it. "For parents, it is difficult to accept, and for us medical staff, it is very regrettable."
The event that Professor Zeng Mei remembers most was in 2009, when a school in Shanghai had a flu outbreak, and 50%-70% of the children in some classes were sick and had no way to attend classes, so the school had to close. It was also in that year that many severe cases were also received in major hospitals across the country. "In that year, some children with severe influenza lost their health, and some children even lost their lives." Since then, Professor Zeng Mei has paid more and more attention to the prevention and control of influenza.
Influenza is not a "minor illness" or can be fatal. Influenza increases the risk of contracting pneumonia by 100 times, cardiovascular disease patients are 10 times more likely to die from flu complications than the average person, and the flu may be the last straw to overwhelm diabetics, increasing the risk of severe illness in diabetics by 6 times. Professor Sun Tieying of the Department of Respiratory and Critical Care Medicine of Beijing Hospital said, "Especially for infants, children, schools and other key places, the elderly, etc., influenza vaccination can reduce the risk of serious complications, and influenza vaccination is the most effective means of preventing influenza." ”
In addition, in each winter and spring, the probability of children getting the flu is the highest, if at school, suddenly found that many children have fever, similar to cold symptoms, you must realize that the flu may come. At this time, we must go to the doctor in time and take corresponding prevention and control measures.
Vaccines are an important means of preventing influenza
Epidemiological studies have shown that for influenza A, the peak of influenza A (north of 33° north latitude) generally occurs from January to February, the southern region (south of 27° north latitude) generally occurs from April to June, while the central region (27.4° to 31.3° north) has two influenza peaks from January to February and June to August; for influenza B, the peak of influenza in most parts of the country occurs from December to April.
In view of the characteristics of influenza viruses that are easily mutated, the protective effect of influenza vaccines has also attracted public attention.
Influenza virus mutations are so frequent that if the strains circulating this year are different, last year's vaccine would naturally be useless. Therefore, every year, the manufacturer of influenza vaccine will produce a new influenza vaccine according to the recommended components of the influenza vaccine issued by the World Health Organization that year. This is also why the flu vaccine is needed every year.
What happens after the flu vaccine enters the human body?
At present, China's influenza vaccines mainly have two categories: inactivated vaccines and live attenuated vaccines. When the body is vaccinated with an inactivated vaccine or a live attenuated vaccine, the immune system is activated, producing antibodies against the vaccine antigen and producing immune memory. Usually, after getting the flu vaccine, it takes about 2-4 weeks to produce antibodies with protective levels. After that, when the influenza virus invades the body, it will be ruthlessly "eliminated".
How to choose a flu vaccine? Either vaccine only covers the strains that are most likely to "run rampant", and it is impossible to protect against all influenza viruses. Trivalent and quadrivalent vaccines are not so-called "high or low", their quality is qualified, and they are produced according to the latest WHO recommendations. The current influenza virus circulating in China, B (Victoria) is absolutely dominant, trivalent and quadrivalent vaccines contain this strain, so the number of vaccine prices is not a problem, the problem is to timely vaccination, improve vaccination rate. Yu Wenzhou, chief physician of the Immunization Program Center of the Chinese Center for Disease Control and Prevention, told the 21st Century Business Herald that the choice of influenza vaccine can be considered from the following aspects:
First, the "protective power" of influenza vaccines. According to the influenza surveillance data released on the who official website, from September 27 to December 26, 2021, the proportion of influenza vaccines covering the main circulating strains (BV strains) in China was: 99.10% trivalent and 99.11% quadvalent. This means that the public can receive considerable immune protection regardless of the amount of flu vaccine they receive during the current flu season.
Second, the wide range of people in which influenza vaccines are available. For special groups such as infants and young children and pregnant women under 3 years old, it is necessary to pay attention to choosing vaccines suitable for self-vaccination, and only imported brand trivalent inactivated influenza vaccine is suitable for all people aged 6 months and above.
Third, the cost performance of influenza vaccines. In the absence of a significant difference in the "protective power" of trivalent inactivated influenza vaccine and quadrivalent inactivated influenza vaccine this year, a more cost-effective vaccine can be selected, and the whole family can save a cost if they are vaccinated.
At the right time for the influenza epidemic, Chief Physician Yu Wenzhou reminded the public that influenza vaccines can be given throughout the flu season to ensure timely immunization protection.
However, many people believe that the new crown vaccine can improve immunity to the virus, falling into the cognitive misunderstanding that "after the new crown vaccine, there is no need to get the flu vaccine again". In fact, COVID-19 vaccination can only raise antibody levels against the new crown virus. There is currently no evidence that COVID-19 vaccination produces immune protection against influenza, so covid-19 vaccination does not prevent influenza.
However, from the current situation, the annual influenza vaccination rate of the whole population in China is only 2-3%, while the adult influenza vaccination rate in developed countries is generally above 50%, which means that it is difficult to form a herd immunity barrier in China.
This is also an important reason for the frequent occurrence of influenza infections on campuses this year. Studies have shown that influenza B viruses are susceptible to transmission in groups of children aged 5-15 years. The age distribution of influenza B in China from 2011 to 2019 showed a double peak, with the viruses of both lines having the highest positive rate in the 5-15 age group and the peak at 10 years old, while the B/Victoria virus was the secondary peak in the 25-35 age group.
Professor Yu Hongjie believes that there are many reasons for the low vaccination rate in China: on the one hand, the current influenza vaccine is a second-class vaccine that needs to be self-funded, and the publicity is not enough; on the other hand, the public's understanding of influenza vaccines and influenza viruses is not in place, and they are unwilling to spend energy to vaccinate.
"The flu vaccine requires people to voluntarily and voluntarily go to the hospital to get it, it is not like other vaccines that can be vaccinated once, the flu virus is prone to mutation, and the current flu vaccine needs to be vaccinated every year." Professor Yu Hongjie said that at present, it is important to raise public awareness of the importance of vaccination.