November 1st is World Influenza Day every year. In autumn and winter, the temperature changes greatly, which is also the high incidence period of various respiratory diseases such as influenza.
What’s the difference between flu and common cold? How to prevent influenza is the most effective? A few days ago, our reporter interviewed Vicke Wang, deputy director of the Department of Respiratory and Critical Care Medicine of China-Japan Friendship Hospital.
Influenza ≠ common cold
People at high risk should be careful.
Reporter: Is the flu and the common cold the same thing? What’s the difference between them?
Vicke Wang: The flu is different from the common cold. The full name of influenza is influenza, which is an acute respiratory infection caused by influenza virus. Influenza viruses are divided into four types: A, B, C and D, but influenza A and B are mainly prevalent in human beings, among which influenza A is more common. At present, people are mainly infected with H1N1 and H3N2 subtypes of influenza A virus and Victoria and Yamagata strains of influenza B virus.
The common cold is usually caused by virus infection, including rhinovirus, adenovirus, respiratory syncytial virus, etc., and a small number is caused by bacterial infection. The clinical symptoms of the common cold are usually mild, mainly manifested as runny nose, cough, nasal congestion, sore throat, fever, etc. (usually manifested as low fever), which usually heals itself within one week and rarely affects normal work and study.
Compared with the common cold, influenza is highly contagious, with acute onset, more serious symptoms and greater potential harm-it not only affects the respiratory tract, but also causes systemic symptoms, such as high fever (usually over 38.5 degrees Celsius), headache, joint pain, muscle aches, fatigue and loss of appetite, and may also cause complications such as pneumonia, myocarditis, hepatitis, encephalopathy and septic shock. Among them, pneumonia is the most common complication, and a few severe cases progress rapidly and may die of acute respiratory distress syndrome or multiple organ failure. Some people are at higher risk of serious complications after being infected with influenza virus, including the elderly over 60 years old, children under 5 years old, pregnant women and patients with basic diseases.
Reporter: According to your observation, has the number of flu patients who came to the hospital recently changed? Is the seasonal epidemic peak coming?
Vicke Wang: Recently, the number of influenza patients in the fever clinic, emergency department, respiratory department and pediatric clinic in the hospital has not changed much compared with the previous period, and there is no obvious seasonal epidemic peak. However, this does not mean that we can take it lightly. Past experience shows that the high incidence of influenza is usually concentrated from the end of November to March of the following year. We still need to take precautions and remain vigilant.
Reporter: What are the main modes of transmission of influenza?
Vicke Wang: Influenza virus is mainly transmitted by respiratory droplets produced by sneezing and coughing of infected people, and can also be directly or indirectly infected through oral cavity, nasal cavity, eyes and other mucous membranes. In certain places, such as crowded, closed or poorly ventilated rooms, it may also spread by aerosol. People are generally susceptible to influenza virus, and influenza patients and asymptomatic infected people are the main sources of influenza infection. Therefore, in daily life, we should take protective measures such as wearing masks, washing hands frequently and keeping social distance to reduce the chance of virus transmission.
Vaccinate against influenza
Is that most direct and effective mean to prevent influenza.
Reporter: How to prevent the flu is the most effective? What measures can the public take?
Vicke Wang: Vaccination against influenza is the most direct and effective means to prevent influenza. It is generally recommended to vaccinate against influenza before the start of the influenza epidemic season. For example, it is very suitable to vaccinate now. According to the virus types covered by the vaccine, influenza vaccines include trivalent and tetravalent influenza vaccines, where "valence" refers to the number of virus types and subtypes covered in the vaccine. Trivalent influenza vaccine can prevent infection of three subtypes of influenza virus, including influenza A H1N1, influenza A H3N2 and influenza B Victoria; tetravalent influenza vaccine can prevent infection of four subtypes of influenza virus, including influenza A H1N1, influenza A H3N2, influenza B Victoria and influenza B Yamagata.
All people who are ≧6 months old and have no vaccination contraindications should be vaccinated against influenza, especially high-risk groups such as the old, weak, pregnant and small, that is, the elderly over 60 years old, people with chronic basic diseases, pregnant women and children under 5 years old. In addition, some specific occupational groups, such as medical workers, vulnerable people and employees in old-age care institutions, child care institutions, welfare homes and other crowd gathering places, primary and secondary school teachers, nursing staff or family members who take care of babies and the elderly, are recommended to be vaccinated against influenza as long as there are no contraindications.
Reporter: Why should the flu vaccine be vaccinated every year?
Vicke Wang: Influenza viruses are prone to mutate, and the influenza virus strains targeted by influenza vaccines in different years may be different. Therefore, we will prepare new influenza virus vaccines every year according to the virus mutation prevailing in the previous year; at the same time, the immunity obtained after vaccination will decay with time. In order to provide more effective protection, it is recommended to vaccinate influenza vaccines every year.
The current influenza vaccine has been developed and improved for many years, and its effectiveness and safety are guaranteed. Although there may be slight uncomfortable reactions after vaccination, these reactions are controllable and insignificant compared with the protective effect brought by the vaccine.
Reporter: Some people have reported that why did they get the flu vaccine?
Vicke Wang: There may be such a situation, and the main reasons may be as follows: no vaccine inoculated by human body can be 100% prevented, and influenza vaccine is no exception; although influenza vaccine may not completely prevent the occurrence of influenza, it can effectively prevent the severe illness caused by influenza and reduce the impact of dangerous and severe illness; the protective effect of influenza vaccine is achieved by producing protective antibodies, and it takes time to produce antibodies. It is usually established within 2 to 4 weeks after vaccination. For people with low immunity, antibody production may be slower and take longer. In the time window before antibody production, if you are exposed to influenza virus and infected, the vaccine may not provide protection, and there is the possibility of missing the protection time window.
Research and practice in recent decades have proved that influenza vaccination is an effective means to prevent influenza and reduce influenza-related severe illness and death. In addition to influenza vaccination, we should also pay attention to personal hygiene, do a good job in hand cleaning and disinfection; pay attention to indoor ventilation, keep the air fresh; go to crowded and poorly ventilated public places less, wear masks when necessary; ensure adequate sleep, eat a balanced diet, and strengthen physical exercise.
Never take antibiotics by yourself.
Take antiviral drugs as soon as possible after diagnosis.
Reporter: If you have flu symptoms, do you have to go to the hospital for examination? Can I wait for my own recovery or take medicine at home?
Vicke Wang: It depends. Most of the flu is self-limited, that is, it can be relieved by itself. Most of them have a fever for 3-5 days, and symptoms such as cough and fatigue gradually improve. For example, young people who have no basic diseases should observe and rest first. If the symptoms are mild, they can be relieved by rest, drinking more water and symptomatic treatment. If there is persistent high fever, suffocation, shortness of breath, or blood in sputum and decreased blood oxygen saturation, they should seek medical attention immediately.
For high-risk people and flu patients with severe symptoms, especially the elderly with basic diseases, it is suggested that they should go to the hospital in time when they have symptoms of fever, cough, headache and fatigue. If they are diagnosed with flu, they should use corresponding antiviral drugs as soon as possible to reduce the risk of illness deterioration. If the patient has other complications or aggravation of the basic disease during the flu, he should also seek medical advice in time.
There are also some precautions for taking medicine at home. First of all, don’t abuse antibiotics by yourself. Antibiotics are ineffective for influenza treatment, because antibiotics are mainly aimed at bacterial infections, and influenza is caused by viruses. If there is mixed infection, medication should be taken under the guidance of a doctor. Before taking antiviral drugs, we should check its interaction with existing drugs (such as antihypertensive and hypoglycemic drugs). When taking drugs, we also need to consider factors such as weight, liver and kidney function, and adjust the dosage according to liver and kidney function.
Reporter: If someone around you has the flu, is it necessary for others to take drugs in advance to prevent it?
Vicke Wang: It is not recommended to take drugs to prevent influenza when you have not been in contact with flu patients, because it is unnecessary. If you have been in close contact with influenza patients and are very worried about being infected, you can take oral anti-influenza drugs for prevention, which is called "post-exposure prevention". As for the preventive measures before exposure, it is suggested to wear masks and wash hands frequently to reduce the risk of infection before knowing that you will be in contact with influenza patients, rather than taking drugs to prevent it.
If a family member is infected with the flu, we should focus on the infected person, let him take antiviral drugs as soon as possible, and reduce contact with other family members. Early treatment of infected people will not only help them recover, but also reduce the infection risk of family members, especially when there are high-risk groups such as the elderly, patients with basic diseases or children at home. In this case, other family members do not need to take drugs in advance to prevent it, but should let the infected people get treatment as soon as possible to reduce the risk of virus transmission in the family.
Reporter: If you are confirmed to have the flu, how should you treat it?
Vicke Wang: Once the flu is diagnosed, you can take antiviral drugs as soon as possible under the guidance of a doctor. 48 hours after onset is the golden period of influenza treatment. At this time, virus replication is active. Early medication can improve symptoms as soon as possible, shorten the course of disease and reduce the probability of severe illness. At the same time, symptomatic treatment is needed, such as using antipyretic drugs when there is a high fever and antitussive drugs when there is a severe cough.
As we said earlier, antibiotics are only for bacterial infections and do not directly treat influenza, but patients with severe influenza often have or have secondary bacterial infections. The influenza virus attacked the airway epithelium of human body like a fire, and it showed "burn-like" performance. Serious damage can easily attract other germs, such as bacteria and fungi, and antibiotics are needed at this time. What needs to be clear is that this requires professional doctors to judge.
Reporter: If you get the flu, won’t you get it again in the near future? In a short time, can a person be infected by different influenza viruses?
Vicke Wang: If you get the flu once, you won’t get it again in a short time. However, with the passage of time, for example, every six months, the antibody level gradually drops, and it is possible to be infected again.
Can a person be infected by different influenza viruses? This is possible because there is no cross-immune protection between different types of influenza viruses, but the probability is small. In the same season, the probability of simultaneous epidemic of influenza A and influenza B is relatively low, and the probability of continuous infection of the same person by two types of viruses in a short period of time is relatively low.
It should be noted that after getting the flu, you should have a good rest, do not recommend working immediately, and pay attention to the changes of physical symptoms. If you have symptoms such as cough and expectoration, you should be careful whether there is secondary bacterial infection, because the airway mucosa is damaged after the flu, and it is vulnerable to other germs during the repair process. In order to protect yourself, it is recommended to continue wearing a mask in public.
People’s Daily Overseas Edition (09th Edition, November 01, 2024)
