When influenza A strikes, doing this right is more effective than grabbing oseltamivir

Audit expert: Gu Haitong

Deputy Chief Physician, Department of Respiratory Medicine, Beijing Tongren Hospital, Capital Medical University

Recently, more and more friends around me have unfortunately been infected with the "H1N1" virus. Not only have many schools suspended classes because students have been infected with the virus, but even my colleagues in the office have also developed symptoms such as headaches and fevers.

Source: pexels

Along with H1N1, oseltamivir, a commonly used antiviral drug for H1N1 , also became a hot topic. There was even a buying spree, with many pharmacies running out of stock.

Source: Screenshot of Weibo topic

What kind of flu is H1N1? Is Oseltamivir a "miracle drug"? Let's take a look today. Friendly reminder: follow the doctor's advice when taking medicine, and don't take medicine at will!

Why is it called "A" flu?

The "A, B, C, and D" of influenza are actually related to the core protein of the influenza virus . According to its core protein, influenza virus can be divided into four types: type A (A), type B (B), type C (C), and type D (D). Among them, type A influenza is more common and is seasonally prevalent every year.

The main influenza viruses prevalent in the population include: influenza A H1N1 subtype, influenza A H3N2 subtype, influenza B Yamagata type, and influenza B Victoria type.

Source: pexels

According to the China Influenza Surveillance Weekly Report for the 7th week of 2023 released by the China National Influenza Center, influenza A has been the most aggressive recently. According to the news released by the Beijing Center for Disease Control and Prevention on February 22, among the influenza viruses currently prevalent in Beijing, influenza A H1N1 subtype accounts for 64%, influenza A H3N2 accounts for 35%, and influenza B accounts for 1%. In terms of percentage data, influenza A virus has an absolute advantage.

Flu generally presents with acute onset, fever (some cases may have high fever, up to 39-40℃), accompanied by chills, chills, headache, muscle and joint pain, extreme fatigue, loss of appetite and other systemic symptoms, often with sore throat, cough, nasal congestion, runny nose, discomfort behind the sternum, facial flushing, mild conjunctival congestion, vomiting, diarrhea and other symptoms. Mild flu often presents similarly to the common cold, but the fever and systemic symptoms are more obvious.

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In addition, compared with the recently popular Norovirus, influenza mainly presents symptoms such as fever, muscle aches, and fatigue, and the digestive tract symptoms are milder. Norovirus can cause vomiting, fever, abdominal pain, and diarrhea, and the digestive tract symptoms are relatively more severe. Therefore, if diarrhea occurs, it should be considered that it may be a Norovirus infection.

What kind of medicine is oseltamivir?

Oseltamivir (English: Oseltamivir), also known as Tamiflu, is the first antiviral drug approved worldwide. It is a neuraminidase inhibitor that blocks the spread of influenza viruses and ultimately achieves the effect of treating or preventing influenza A and influenza B viruses, but it does not neutralize the virus.

Oseltamivir molecular ball-and-stick model source: Wikipedia

The mechanism of action of neuraminidase inhibitors such as oseltamivir is to prevent the virus from being released from infected cells and invading neighboring cells, thereby reducing the replication of the virus in the body. If patients take it within 48 hours of onset, the incidence of severe influenza and death can be significantly reduced.

The drug was discovered by scientists at Gilead Sciences, Inc. Oseltamivir requires the use of shikimic acid extracted from star anise , which was originally only available from star anise and can later be synthesized by Escherichia coli through genetic technology. In 2006, 30% of the raw material supply was produced by recombinant Escherichia coli.

Star anise source | Wikipedia Sanjay Acharya

Oseltamivir phosphate has only extremely low toxic effects on humans and animals, and due to the relative conservatism of neuraminidase, it is not easy to develop drug resistance, and is considered a reserve drug for the prevention and treatment of influenza.

Precautions when using oseltamivir

Some friends may ask: "Since oseltamivir can fight viruses and treat influenza, is it also effective for the new coronavirus? " In fact, there is no oseltamivir in the 10th edition of the treatment plan for new coronary pneumonia. The reason is: Oseltamivir is a selective inhibitor of influenza virus neuraminidase, and the culprit of this new coronary pneumonia, the new coronavirus, does not have neuraminidase, so oseltamivir is naturally ineffective against it.

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Although oseltamivir has a certain effect on inhibiting influenza A virus, its use should also be cautious. "Oseltamivir is a prescription drug, so you must be careful when using it." Li Liyan, director of the Emergency Infection Department of Beijing First Hospital of Integrated Traditional Chinese and Western Medicine, said that oseltamivir can be used as an emergency temporary preventive measure for people at high risk of severe influenza who have no immunity. It is best to use it under the guidance of a doctor and should not be taken on your own.

In general, oseltamivir has rare side effects, good safety, and can be used by both the elderly and children.

How to prevent influenza A?

So, how should we prevent influenza during the peak influenza season?

In fact, the prevention of respiratory infectious diseases is similar. Some of the methods for preventing COVID-19 infection are also methods for preventing influenza, and can also help reduce the risk of norovirus infection.

For influenza, the preventive effect of oseltamivir cannot be compared with that of influenza vaccine. The preventive effect of drugs is very short-lived and can only play an emergency temporary preventive effect, but influenza vaccine is different. Immunity after influenza vaccination can last for several months to a year. Universal vaccination during influenza pandemics can significantly reduce the spread of influenza viruses. Therefore, oseltamivir cannot replace influenza vaccination, and timely influenza vaccination is the most effective means of preventing influenza. During the peak influenza season, open windows for ventilation. It is recommended to open windows for ventilation at least 3 times a day, and ventilate for at least 30 minutes each time to keep the indoor air fresh.

We should develop good habits, pay attention to personal hygiene, wash our hands frequently, and try to avoid touching our eyes, nose or mouth; pay attention to respiratory hygiene etiquette, cover our mouth and nose with tissues or towels when coughing or sneezing; pay attention to maintaining healthy living habits, eat a balanced diet, exercise moderately, and get enough rest.

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In addition, if you have flu symptoms such as fever, cough, sore throat, etc., do not go to work or school while sick. Patients with mild symptoms are encouraged to self-monitor at home. If the condition progressively worsens, you should wear a mask and go to the hospital for treatment.

The content of this article is compiled from Wikipedia, public accounts: Beijing Medical Management, China News Service, CCTV.com, Beijing Center for Disease Control and Prevention, etc.