Influenza A is an acute respiratory infection that can affect people of all ages, especially during the coldest months of the year. In this article, we explain what influenza A is, how it spreads, the most common symptoms, and how it can be treated and prevented.
What is influenza A?
Influenza A is an acute respiratory disorder caused by the influenza A virus, one of the primary causes of seasonal influenza outbreaks every year. The most common subtypes of this virus include H1N1 and H3N2, which are most frequently associated with these outbreaks.
What are the symptoms of influenza A?
The symptoms of influenza A are similar to those of other flu-like infections, which can make it difficult to diagnose based solely on the symptoms. The most common signs include:
• Fever;
• Cough;
• Nasal congestion;
• Sore throat;
• Aching muscles or body;
• Headache;
• Chills;
• Severe fatigue;
• Vomiting or diarrhoea.
You should seek medical assistance if the symptoms are severe, fever persists for several days or if you experience difficulty breathing, extreme fatigue or clinical deterioration. If you belong to a high-risk group where respiratory infections can aggravate your underlying condition or, conversely, your underlying condition may aggravate a respiratory infection, then you should seek medical care as soon as possible.
The incubation period, which is the time between exposure to the virus and the onset of the first symptoms, is usually between 3 and 10 days. During this stage, the person may not present any symptoms yet, and the likelihood of spreading the virus is lower.
Is influenza A contagious?
Influenza A is extremely contagious and spreads from person to person through droplets released when an infected person coughs, sneezes or talks (respiratory route). Therefore, close contact with people exhibiting symptoms should be avoided, as these droplets can be inhaled and cause an infection.
People with influenza A are generally most contagious in the first few days of their illness, and this decreases as fever improves. Furthermore, influenza A can have a greater impact on certain groups of the population, particularly people with a more vulnerable medical condition or immune system. This applies to people who are immunocompromised, with HIV/AIDS infection, diabetes, who are pregnant (especially in the second and third trimesters), up to two weeks after giving birth, children under 2 years old, and people with chronic conditions.
How long does influenza A last?
Influenza A usually lasts around 7 days. In most cases, symptoms begin to improve gradually throughout the first week of the illness. Furthermore, the virus’s ability to spread decreases substantially after around two days without fever.
Influenza A and B: what are the differences
Influenza A and influenza B are two types of seasonal flu caused by different viruses that belong to the same influenza virus group. Although the symptoms are very similar, there are important differences.
The main difference lies in the type of virus causing the infection. Influenza A is caused by the influenza A virus, while influenza B is caused by the influenza B virus. Both circulate during the flu season and account for most cases of seasonal influenza.
From a clinical perspective, the symptoms are almost identical, including fever, cough, body aches, sore throat, fatigue and nasal congestion. This is why it is not possible to differentiate between influenza A and influenza B based on symptoms alone.
The type of influenza can only be confirmed through laboratory testing, usually performed with nasopharyngeal swabs, similar to those used for other respiratory infections.
How to relieve influenza A symptoms?
The treatment for influenza A is essentially symptomatic and the purpose is to relieve discomfort while the body fights the infection. Some practices can help you recover and get back to normal as soon as possible:
• Rest at home, not only to help improve symptoms, but also to reduce the risk of spreading the infection to others;
• Avoid wearing too many layers, to allow body heat to dissipate;
• Monitor body temperature;
• Take painkillers, such as paracetamol, when advised and in doses appropriate to age or weight;
• Medicate children in accordance with medical instructions;
• Avoid taking medication without medical advice during pregnancy or while breastfeeding;
• Regular nasal irrigation helps relieve nasal congestion;
• Do not take antibiotics without a prescription, as these are not effective against viral infections;
• Drink fluids (water, tea, flavoured waters, etc.) frequently throughout the day;
• Seek regular support, especially if you live alone or are in a vulnerable situation.
How to prevent influenza A?
Influenza A prevention involves above all good hygiene and reducing the risk of spreading the virus to others. Therefore, in case of infection or close contact with other sick people, it is advisable to:
• Avoid sharing closed spaces with others;
• Maintain physical distancing whenever possible;
• Wear a face mask indoors or when in close contact with others;
• Ventilate indoor spaces frequently;
• Disinfect frequently touched surfaces;
• Wash hands regularly;
• Practise good respiratory hygiene (cough or sneeze into your elbow or a disposable tissue).
Vaccination is an important measure to prevent seasonal flu, as this provides protection against the influenza A and influenza B viruses.
