Why are respiratory infections so severe this year? Is it because our immune system has weakened, or is it because the virus is stronger?

Since the beginning of winter this year, respiratory infections have entered a peak period in various regions. This round of respiratory infectious diseases shows a trend of multiple pathogens co-prevalent, with the peak of infection being mainly some common respiratory diseases such as the new coronavirus, influenza virus, mycoplasma pneumoniae, and respiratory syncytial virus .

In response to this wave of respiratory infections, Science Popularization China invited Li Dongzeng, chief physician of the Comprehensive Infection Department of Beijing Youan Hospital, to explain in detail the common misunderstandings about respiratory diseases on the Internet.

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Why is there a peak in respiratory infections this winter?

Is it “immunity debt”?

The number of respiratory infections this winter exceeds the same period in previous years, and the infected are mainly children and young and middle-aged people, with relatively few elderly people. Similar situations occur in many countries and regions around the world.

At present, mainstream scholars including experts from the World Health Organization have considered that it is related to "immune debt" or "immune gap" . Due to the impact of the COVID-19 pandemic in the past few years, people have reduced the infection of various respiratory pathogens by wearing masks, washing hands frequently, reducing unnecessary gatherings and going out, etc., which has led to a decrease in the immune barrier of the group against respiratory pathogens, especially in the children group. This immune gap is more obvious.

In addition, infectious diseases have their own epidemic cycles, usually with an epidemic peak every 3 to 7 years. This year, many pathogens happen to have reached their epidemic peak.

Multiple respiratory pathogens are prevalent.

Will superimposed infection increase the incidence of severe illness?

As multiple pathogens are prevalent, superimposed infections, mixed infections, and repeated infections do exist, which may lead to longer illness courses, more complex symptoms, higher risks of severe illness, and increased demand for hospitalization.

From the perspective of social media,

I feel that there are a lot of patients with Mycoplasma pneumoniae.

Is this really the year of mycoplasma?

Mycoplasma pneumoniae infection also has an epidemic cycle, and there is indeed a relatively obvious epidemic peak every 3 to 7 years. This year, the number of people infected with Mycoplasma pneumoniae has increased significantly compared with previous years. The main reason is that it conforms to the objective law of epidemics. After a few years of epidemic troughs, the immune barrier of the population decreases, and there will be an epidemic peak.

In addition, with the advancement of detection methods, the detection rate of mycoplasma will increase, and the number of detected people will also increase. It is indeed important to note that the detection and antibody testing of many medical institutions will lead to an increase in false positive rates . Because there are many mild and latent infections of mycoplasma itself, some people's antibody positivity may be due to past infection, not necessarily recent infection, which may lead to a high false positive rate of mycoplasma and affect subsequent treatment plans and treatment effects.

The current influenza infection rate continues to rise.

Is it still too late to get vaccinated now?

There is still time, and if you can get vaccinated, you should get vaccinated as soon as possible.

Flu vaccination is an effective way to prevent influenza, which can effectively reduce the incidence of influenza and the probability of severe illness and death after infection. Usually 2 to 4 weeks after influenza vaccination, the human body will produce antibodies with protective levels.

The current influenza infection rate is relatively high, especially for people at high risk of severe influenza cases. It is recommended to get vaccinated as soon as possible, which will not only reduce your own risk of infection and severe illness, but also protect family members.

People who have been infected with influenza virus but have not received influenza vaccine are also recommended to get vaccinated as soon as possible . In the same influenza season, there may be 2 or even 3 different influenza virus strains circulating at the same time. Infection with one virus will not make the body immune to other viruses. Flu vaccination can prevent multiple influenza virus infections.

For example, this winter's flu is caused by the influenza A H3N2 strain, but a small number of flu cases are caused by the influenza B strain. Therefore, even if you have been infected with the influenza A virus, vaccination can provide additional protection against the influenza B virus.

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In case of infection,

How to confirm which pathogen is infecting you?

Is it important to know which pathogen you are infected with?

If you have symptoms, you need to try to analyze and evaluate which pathogen you are infected with, which is meaningful for the treatment and prevention of the disease. So how do you determine which pathogen you are infected with?

The first is to judge based on contact history.

Try to find out whether there are people with fever and respiratory symptoms among the people you have contacted, and whether there are people who have been diagnosed with influenza or Mycoplasma pneumoniae infection. These contact histories are important for determining which pathogen you are infected with. For example, if you develop symptoms such as fever, cough, and sore throat after contacting an influenza case, you are likely to have been infected with the influenza virus.

The second is to judge based on symptoms.

The typical symptoms of influenza are rapid onset, high fever, cough, sore throat, obvious fatigue, headache, muscle aches, joint pains, etc., while the onset of Mycoplasma pneumoniae infection is relatively slow, and the typical symptoms are repeated high fever, mainly dry cough in the early stage, and sputum in the later stage. The symptoms of the common cold are relatively mild, with no fever or only low fever. The typical symptoms are usually nasal congestion, runny nose, sneezing, cough, sore throat, and generally heal within 3 to 5 days.

It is meaningful for patients to know which pathogen they are infected with, both for the treatment and prevention of the disease, especially influenza. Early diagnosis can allow for early antiviral treatment, reduce the risk of severe illness, shorten the course of the disease, and reduce the risk of infection. Especially for people at high risk of severe cases, early antiviral treatment can effectively reduce the risk of severe and critical illness.

In addition , influenza is a legal infectious disease in China. After diagnosis, it should be isolated in time to avoid spreading to people around . For Mycoplasma pneumoniae or some bacterial infections, the use of antibiotics after diagnosis can also reduce the risk of severe illness and shorten the course of the disease. However, there is a lack of effective antiviral drugs for respiratory syncytial virus, adenovirus, rhinovirus, etc., and treatment is mainly symptomatic.

A cold and fever,

Do I need to see a doctor immediately?

Or under what circumstances should one seek medical treatment?

The common cold usually has mild symptoms and can heal itself in about 3 to 5 days. Usually, you do not need to go to the hospital for treatment. You can rest at home and use antipyretic and analgesic drugs, antitussive and expectorant drugs to relieve the discomfort. If you still have repeated high fever, shortness of breath, wheezing, difficulty breathing, chest tightness, chest pain, poor appetite, mental depression, drowsiness and other serious conditions for more than 3 days, you need to see a doctor in time.

After catching a cold and having a fever,

What should I pay attention to if I am caring at home?

If you have cold and fever symptoms, you should rest in time and try to stay away from your family members, and try to choose a room with a separate window for isolation. If you cannot avoid contact with your family members, both parties should wear masks and try to keep a certain distance to reduce the risk of family transmission, especially to protect the elderly, children, pregnant women and other people with underlying diseases and low immunity at home, and avoid close contact.

Patients should ensure adequate rest, increase fluid intake appropriately, and choose antipyretic and analgesic drugs, cough and expectorant drugs according to symptoms. If the condition worsens significantly, or there is no improvement trend for more than 5 days, you need to see a doctor in time.

This wave of respiratory disease infection peaks,

How to prevent it?

The first thing to consider is vaccination. If you meet the conditions for vaccination, try to get vaccinated, such as influenza vaccine, new crown vaccine, pneumococcal vaccine, etc. Various vaccines are suitable for different populations. If there are no contraindications to vaccination, you should try your best to protect yourself through vaccination.

Second, people with respiratory symptoms should isolate themselves in time, take protective measures, try to avoid infecting others, do not go to work or school while sick, and do not attend gatherings or visit relatives and friends during illness. Protect yourself by wearing masks, washing hands frequently, opening windows for ventilation, paying attention to coughing etiquette, and maintaining social distance. When going out, try to minimize the time you stay in crowded places with poor air circulation.

During this wave of respiratory infections,

Are there any cases that left a deep impression on you?

What impressed me most this year was that some patients had repeated and mixed infections. A colleague had two children. The first time, the 8-year-old brother got the flu, and within 3 days, the 3-year-old brother also got the flu. I reminded the child's mother that in this case, when the older brother is diagnosed with influenza, the younger brother should be isolated in time, and oseltamivir granules can be considered for post-exposure prophylaxis.

As a result, after the elder brother recovered from the flu and went to school, he was infected with Mycoplasma pneumoniae again within a week. This time, the mother isolated the younger brother in time to prevent him from being infected. However, two weeks later, the elder brother had fever and sore throat again. This time, the doctor found that it was scarlet fever, which is caused by streptococcal infection and is also a respiratory infectious disease.

I was deeply impressed by the fact that a child suffered three respiratory infections in one month. This also suggests that the prevention of respiratory infectious diseases is relatively difficult and everyone should take it seriously.

Planning and production

Author: Li Dongzeng, Chief Physician of the Department of Infectious Diseases, Beijing Youan Hospital

Reviewer: Tang Qin, Director and Researcher of the Science Popularization Department of the Chinese Medical Association

Planning丨Lin Lin

Editor: Lin Lin