Headache, stomachache, joint pain... Why is it so painful to be infected with influenza A? Is it too late to get vaccinated now?

Recently, influenza has been prevalent. According to the latest data from the China Center for Disease Control and Prevention, the positive rate of influenza virus continues to rise, of which more than 99% are influenza A.

Experts remind: In addition to children and people with chronic underlying diseases, young and middle-aged people should not take it lightly. Many disease prevention agencies have issued influenza health warnings, reminding residents everywhere to protect themselves and their families.

Image source: Overview of influenza epidemic situation in China (as of December 29, 2024)

So, what exactly is H1N1? What are the symptoms of infection? Why do many patients feel pain all over their body? How to prevent it? Let's find out in one article today.

What is influenza A?

Influenza virus, as the name suggests, is a virus belonging to the "Myxoviridae". It has four subtypes, and influenza A is one of them:

Type A:

It is easy to mutate, fight across species (humans and animals), and has caused global pandemics many times.

Type B:

Influenza B can also cause seasonal epidemics, usually affecting only humans.

Type C:

It can infect humans, dogs, and pigs, causing only sporadic cases of upper respiratory tract infection and generally not causing epidemics.

Type D:

It mainly infects pigs and cattle and has not been found to infect humans.

There are four different subtypes of influenza virus, B, C, and D, of which A and B are the most common. There are also multiple subtypes of influenza virus A, which are determined by two surface proteins of the virus: hemagglutinin (HA) and neuraminidase (NA). Currently, 18 types of hemagglutinin (HA) and 11 types of neuraminidase (NA) have been discovered. Different combinations can form different virus subtypes. The well-known subtypes of influenza virus A (H1N1) and influenza virus A (H3N2) are the pathogens that have caused serious epidemics.

Everyone is familiar with influenza. In the north, there is an epidemic every winter and spring, while in the south, due to climate problems, there may be epidemic cases all year round.

Headache, stomachache, joint pain...

Why does influenza infection hurt so much?

After influenza infection, most people will experience obvious symptoms, the most typical of which is fever, and the general body temperature can reach 39~40℃. High fever often causes patients to have chills and chills.

In addition, some people may experience systemic discomfort such as fatigue and loss of appetite, accompanied by respiratory symptoms such as cough, runny nose or nasal congestion. Some patients may have gastrointestinal reactions such as nausea, vomiting and diarrhea.

Copyrighted stock images, no reproduction is authorized

But when it comes to influenza, the most impressive thing is the pain! It hurts so much! Not only may you have a sore throat, headache, muscle pain, joint pain... Some people describe that if you have influenza, it's like every part of your body is twisted up like a towel, and every inch of it hurts!

Why does influenza A cause so much pain? This can be said to be a "wrong" accusation against the influenza A virus, but it is not entirely wrong.

Because the pain is not directly caused by the influenza A virus, but when the human body is infected with the virus, it will produce an immune response, releasing antibodies to attack the virus and prevent the virus from spreading further. These proteins not only prevent the virus from spreading in the body, but also cause an inflammatory response in the body, which is the main cause of pain. When inflammation occurs, white blood cells produce cytokines (small proteins used for cell signaling), which can cause inflammation of muscles and joints and thus produce significant pain. The pain itself is certainly unbearable, but fortunately, most pain can be relieved by taking nonsteroidal anti-inflammatory drugs such as ibuprofen.

The most worrying ones are high-risk groups such as infants, pregnant women, the elderly and patients with chronic diseases. They are at high risk of serious complications, their condition may deteriorate rapidly, with a persistent high fever of over 39°C, and may develop acute respiratory distress syndrome (ARDS), sepsis, septic shock, heart failure, renal failure, and even multiple organ dysfunction.

How to prevent it?

Is it still too late to get a flu shot now?

When facing the challenge of influenza, we must remember that "prevention is better than cure". The best way to prevent influenza: get vaccinated! Get vaccinated! Get vaccinated! Get vaccinated...

Although it is recommended to complete the influenza vaccination before the end of October, it is already more than January. Is it too late to get vaccinated now?

Although it is a little late, it is still recommended to get vaccinated now. The main reason is that the peak of influenza epidemics is usually concentrated in late November to February of the following year. This year's influenza peak is delayed compared with previous years. We don't know when we may be infected with influenza, so getting vaccinated now may prevent you from being infected in the future, so vaccination can still play a protective role.

Copyrighted stock images, no reproduction is authorized

Of course, the earlier you get vaccinated, the better the protection, but even getting vaccinated now can reduce your risk of getting the flu. Vaccination can effectively reduce the chance of infection and the likelihood of serious complications. No matter when you get vaccinated, it is always safer to have protection than not.

So if you have been infected this year, do you still need to get vaccinated again?

Although influenza A infection is now the mainstream, in fact, there are multiple influenza virus strains circulating at the same time every year, and it is difficult for scientists to accurately predict which strains will dominate. Even if you have been infected with influenza this year, if you have not received the influenza vaccine this year, you may still be protected by antibodies stimulated by different subtypes of viruses in the vaccine.

There are three main types of vaccines available:

· Live attenuated influenza vaccine: fast onset, long-lasting protection, less pain

Inactivated influenza (subunit) vaccine: few adverse reactions, can be taken if you have enough money

Influenza inactivated (split) vaccine: high quality, low price, high cost performance

No matter which vaccine you choose, the most important thing is to get it in time!

As long as you take oseltamivir or

Can Mabaloxavir cure it?

Oseltamivir and Mabaloxavir are indeed effective antiviral drugs for the treatment of influenza. Their main function is to alleviate symptoms and shorten the course of the disease by inhibiting the replication of influenza viruses. However, taking these drugs alone cannot guarantee full recovery for all patients, especially in severe patients or high-risk groups.

Characteristics of these two drugs:

Oseltamivir: Suitable for children aged 1 year and above and adults, it needs to be taken for 5 consecutive days, twice a day. It is characterized by a wide range of uses, including children of young ages. Studies have shown that after treatment with oseltamivir, viral replication and excretion can be stopped within about 75 hours.

Mabaloxavir: Suitable for children aged 5 years and above and adults. Its biggest feature is that it only needs to be taken once. This is particularly convenient for patients who do not want to take medication for a long time or have difficulty taking medication. Studies have shown that mabaloxavir can quickly stop viral replication and excretion within 24 hours.

The main functions of these two antiviral drugs are to relieve symptoms and shorten the course of the disease, but they cannot completely eliminate the virus. The efficacy varies depending on the severity of the disease and the timing of taking the medicine. The best time to use is within 48 hours of the onset of symptoms.

Copyrighted stock images, no reproduction is authorized

In addition to taking antiviral medicines, people with the flu should take the following steps to help them recover:

Get enough rest: Flu can cause general weakness and fatigue, and rest helps the body better fight the virus.

Drink fluids: Flu is often accompanied by fever and sweating, so drinking fluids can help prevent dehydration.

Symptomatic treatment: Antipyretic and analgesic drugs can be used under the guidance of a doctor to relieve symptoms such as fever, headache and muscle aches.

Prevent secondary infection: Patients should avoid contact with other people to reduce the possibility of cross-infection, wear masks, maintain personal hygiene and isolate at home.

References

[1]https://www.chinacdc.cn/jksj/jksj04_14249/202501/P020250102412903696017.pdf

[2]https://www.health.harvard.edu/diseases-and-conditions/why-does-the-flu-cause-body-aches

[3]https://news.llu.edu/health-wellness/why-do-muscles-joints-ache-during-flu

[4]https://www.hopkinsmedicine.org/-/media/files/health/11flumythsinfographic.pdf

Planning and production

Author: Chen Mo'ao, popular science author

Reviewer: Li Dongzeng, Chief Physician, Department of Respiratory and Infectious Diseases, Beijing Youan Hospital