[Smart Farmers] When H1N1 influenza strikes, how should we respond?

Recently, many people have unfortunately been infected with the "A-type influenza" virus, and have developed symptoms such as headaches and fever. How can you tell if you have been infected with the A-type influenza virus? What is the difference between A-type influenza and common flu?

Why have so many people been infected with influenza A recently?

Influenza A has a peak period. According to previous epidemiological studies, northern provinces north of 33 degrees north latitude in my country have a winter epidemic pattern from January to February, provinces south of 27 degrees north latitude have a peak epidemic pattern from April to June, and provinces between 27 and 33 degrees north latitude have a double peak epidemic pattern from January to February and from June to August each year.

The structure of influenza A virus often mutates, with important antigenic variations occurring every 2-3 years, causing seasonal epidemics.

In addition, influenza A virus has many hosts. In addition to common hosts such as poultry, pigs, and humans, it can also infect mammals such as horses, pinnipeds, and minks.

What symptoms will occur after being infected with influenza A?

The influenza virus has an incubation period, which is usually 1 to 7 days. Patients can usually excrete the virus 24 to 48 hours before symptoms appear, and symptoms will significantly worsen 12 to 24 hours after the onset of symptoms, reaching a peak within 24 hours. Adults and older children generally continue to excrete the virus for 3 to 8 days.

After being infected with influenza A virus, patients mainly present with fever, headache, myalgia and general discomfort. The body temperature can reach 39~40℃, accompanied by chills and shivering, and often accompanied by systemic symptoms such as muscle and joint pain, fatigue, loss of appetite, often with sore throat and dry cough, and may have nasal congestion, runny nose, discomfort behind the sternum, etc.

Some high-risk groups may develop complications after infection, the most common of which is pneumonia. Other complications include nervous system damage, heart damage, myositis, rhabdomyolysis, and septic shock.

I have a fever. How can I tell whether I have influenza A or a common cold?

Compared with the common cold and COVID-19, influenza A has certain differences in clinical manifestations, infectiousness, complications, etc. due to differences in etiology.

Compared with the common cold, influenza A patients have more severe systemic symptoms, often accompanied by high fever (39-40℃), some with chills, longer duration of fever, and more complications, including pneumonia, otitis media, myocarditis, meningitis, etc. It is also more contagious and has obvious seasonality.

How can we prevent influenza A?

Influenza A virus is a virus to which the general population is susceptible.

High-risk groups for severe illness include children aged <5 years (children aged <2 years are more likely to develop serious complications), elderly people aged ≥65 years, patients with complications such as chronic respiratory diseases, obese people (IBM>30), and pregnant and perinatal women.

Maintaining good personal hygiene habits is an important means of preventing respiratory infectious diseases including influenza A, including strengthening physical fitness, paying attention to hand hygiene, keeping the environment clean and ventilated, etc. At the same time, vaccination is an effective means of preventing influenza.

What measures can be taken after being infected with influenza A?

If confirmed to be infected with influenza A virus, patients with mild symptoms can be isolated at home, keep the room ventilated, wear masks, get enough rest, drink plenty of water, and eat a diet that is easy to digest and nutritious. At the same time, it is necessary to closely observe changes in the condition, especially for children and elderly patients.

If the patient's underlying disease worsens, such as symptoms of chronic obstructive pulmonary disease, diabetes, chronic heart failure, or severe symptoms occur, such as persistent high fever for more than 3 days, accompanied by severe cough with purulent sputum, bloody sputum, chest pain, increased respiratory rate or difficulty breathing, changes in consciousness, severe vomiting and diarrhea, and pneumonia, etc., timely hospitalization is required.

Is it necessary for ordinary people to buy oseltamivir in advance?

Oseltamivir, as a neuraminidase inhibitor, can effectively block the further proliferation of the virus. Other similar drugs include zanamivir and peramivir. As prescription drugs, you need to go to the hospital for evaluation and be prescribed by a doctor.

For patients with mild or non-severe symptoms, close observation is required within 48 hours of onset, and antiviral treatment should be considered after full evaluation.

For patients with severe symptoms or high-risk factors, antiviral treatment should be given as early as possible without waiting for test results. Antiviral treatment within 48 hours of onset can reduce complications, lower mortality, and shorten hospitalization time; antiviral treatment after 48 hours of onset can still be beneficial.

The adult dose of oseltamivir is 75 mg twice a day for 5 days. The dose for children needs to be converted according to body weight in kilograms. The course of treatment for severe patients can be appropriately extended. The dose for patients with renal insufficiency needs to be adjusted according to renal function.

Why should we pay attention to prevention and control of key groups in rural areas?

Because influenza A virus is highly contagious, the disease progresses rapidly in patients at risk of severe illness. In rural areas where medical resources are relatively insufficient, it is necessary to strengthen prevention, control and education for key risk groups to further reduce the impact of influenza A virus.

For the majority of rural residents, it is necessary to further strengthen the education of risk groups such as the elderly and children in rural areas, strengthen hand hygiene habits, pay attention to wearing and changing masks, strengthen physical fitness, and pay attention to maintaining good hygiene habits, cover the mouth and nose with upper arms or tissues or towels when coughing or sneezing, wash hands after coughing or sneezing, and try to avoid touching the eyes, nose or mouth; if there are flu-like symptoms such as fever, pay attention to rest and self-isolation, etc. At the same time, it can be combined with traditional Chinese medicine differentiation to strengthen the prevention and treatment of influenza A.

Severely ill patients should be sent to the hospital for treatment in a timely manner to gain the best diagnosis and treatment time; severe patients diagnosed with influenza A should be given antiviral treatment in a timely manner.

Produced by: Popular Science in China to Benefit Farmers

Producer: Guangming Online Science Department

Planning: Zhang Mengfan and Xie Yun

Review expert: Du Boran, Chief Pharmacist of the Pharmacy Department of Beijing Obstetrics and Gynecology Hospital, Capital Medical University