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What You Should Know About Influenza

Verified By Apollo General Physician September 28, 2020 4515 0

Influenza is a contagious viral infection, which causes respiratory illnesses. Commonly referred to as flu, it can attack the throat, lungs, and nose, by spreading through the upper or lower respiratory tract.

Flu mostly appears during the spring and winter seasons, and most of the time, it gets resolved on its own. But sometimes, it causes complications and can turn out to be deadly. So you should know what causes the flu and the ways to treat and prevent it .

The Types of Influenza

Influenza viruses can be categorized into 4 different types, viz., A, B, C, and D. Influenza A and B viruses causes seasonal epidemics of diseases.

  • Type A flu

Influenza A viruses are further divided into subtypes based on two proteins on their surface: Neuraminidase (N) and Hemagglutinin (H). There are 11 different neuraminidase subtypes and 18 different hemagglutinin subtypes and (N1 through N11 and H1 through H18, respectively). Current subtypes of influenza A viruses which routinely circulate in people are: A (H1N1) and A(H3N2). Influenza A subtypes can further be broken down into different genetic “clades” and “sub-clades.

The Influenza A virus constantly keeps changing and is the only influenza virus that is known to cause a global pandemic of flu disease. Wild birds act as hosts for this virus. Type A influenza, known to cause outbreaks and increase risk of disease, can be dangerous. This virus mutates faster compared to influenza B. However, both viruses are always changing, creating new strains from one flu season to another. Previous flu vaccinations may not prevent infection from a new strain. Wild birds are natural hosts for type A virus, also known as bird flu and avian flu. This infection can also transmitted to humans and other animals. This, combined with the ability of type A influenza to mutate faster than type B, can cause pandemics.

  • Type B flu

Unlike Influenza A, the type B virus affects only humans. This type of flu is less severe than the type A flu, but occasionally it can be potentially life-threatening. The type B flu is not classified into subtypes and is not known to cause pandemics. However, it is classified into two different lineages: B/Victoria and B/Yamagata.

  • Type C flu

This virus also affects people but is milder than both types A and B. Influenza C causes mild illness and is not known to cause human flu epidemics.

  • Type D Flu

Influenza D primarily affects cattle and is not known to cause illness in humans.

The Signs and Symptoms of Influenza

Initially, you may experience symptoms of a common cold such as sneezing, sore throat, and a runny nose. One notable factor is while colds develop slowly, influenza tends to be sudden. Where a cold also causes  you to feel sick , with the flu, you will feel much worse.

The common signs associated with influenza include:

  • Body aches
  • Fever
  • Headache
  • Sweats and chills
  • Stuffy or runny nose
  • Shortness of breath
  • Persistent dry cough
  • Eye pain
  • Sore throat
  • Diarrhea and vomiting, commonly observed in children.

Complications arising due to Influenza

If you are healthy and young, the flu usually gets cured within a couple of weeks with no lasting impact. But children and older adults may develop certain complications such as:

People with chronic illness and older adults can experience serious complications with pneumonia.

Who is at risk of getting Influenza?

In most cases, the flu tends to get cured on its own, but sometimes it can turn out to be deadly. People who are at a greater risk of contracting influenza include:

  • Adults over 65 years of age
  • Children below 5 years of age, especially those under 6 months
  • People with a weak immune system
  • Pregnant women and those up to 2 weeks of giving birth
  • Nursing home residents and those in long-term care facilities
  • People suffering from chronic illnesses like metabolic disorders, heart, liver, and kidney disease, asthma, and diabetes
  • People with a Body Mass Index (BMI) of 40 or more

When to consult a doctor?

If your flu infection is getting complicated and cannot be treated at home, you should consult a doctor right away. Taking antiviral drugs may reduce the length of your suffering and prevent severe complications.

In case of any emergency , get medical help immediately. Some of the symptoms of medical emergency include:

  • Continuous dizziness
  • Chest pain
  • Seizures
  • Breathing problem or breathlessness
  • Muscle pain or severe weakness
  • Deteriorating medical condition

How is Influenza transmitted?

The influenza virus is transmitted through the air when a virus-infected person sneezes, talks, or coughs. You can also inhale the droplets directly or pick up from an object that has been touched by an infected person and transfer them to your nose, mouth, or eyes.

People infected by the virus become contagious about a day before the occurrence of the symptoms and stays up to five days. People with weaker immune systems and children may stay contagious for a longer period.

If you have had influenza before, your body has become immune to fight that specific strain of the virus. But as the influenza virus mutates and forms  new strains regularly, you are always vulnerable to get infected by a new strain. Also, antibodies may decline over time which increases your risk of getting influenza even if you had suffered from the same strain of the virus before.

Treatment options for Influenza

Most of the time, you will need nothing more than a few days of rest and lots of fluids to treat the flu. But if you are at a greater risk of encountering complications or experiencing severe problems, your treating doctor may advise you to take an antiviral drug. The commonly prescribed drugs include zanamivir, oseltamivir, baloxavir, and peramivir. Taking these drugs as prescribed may shorten your illness slightly.

Older antiviral medicines like rimantadine and amantadine are no longer effective as the circulating strains of influenza have become resistant to such drugs.


Call 1860-500-1066 to book an appointment.

Preventing Influenza

Every person beyond the age of 6 months should take the annual flu vaccination, as recommended by The Centers for Disease Control and Prevention (CDC). Taking the vaccine can reduce your possibility of getting infected by the virus and lower the likelihood of experiencing severe complications from the disease.

Preventing influenza or reducing the severity of the illness minimizes the need to stay in the hospital. The seasonal flu vaccine protects you from 3 to 4 common flu viruses during the year.

While the flu vaccine in the form of nasal spray is in use, it is not recommended for a certain class of people such as children between 2 to 4 years of age suffering from wheezing or asthma, pregnant women, and those with a compromised immune system.

Since most types of the influenza vaccine contain a certain amount of egg protein, you should take the vaccine under medical supervision if you have a severe egg allergy.

How to prevent contracting influenza when a family member has it

By following a few simple rules at home you can prevent the flu from spreading:

  • Get vaccinated on time.
  • Cover your mouth while coughing or sneezing.
  •  Wash your hands often.
  •  Keep your environment clean.
  • Avoid touching your nose, mouth, and eyes.
  • Limit contact with the family member who has contracted the flu.


Since it has become quite difficult to distinguish between the common flu and the novel coronavirus, it is better to take medical help rather than risk your life and try to self-treat the illness at home. Always maintain a distance of at least 2 meters from other people, wear a mask and wash hands often with soap and water or sanitser to prevent any viral infection from spreading, be it influenza or COVID -19.


  1. Which is worse: Influenza A or B?

    Some influenza A subtypes may lead to more severe disease than others. For instance, as per the US-based CDC (Centers for Disease Control and Prevention), influenza A (H3N2) viruses, in the recent past, have been linked to more hospitalizations and deaths in the elderly and children than in other age groups.

    At one time, it was thought that influenza A infection was more severe compare to influenza B infection. But, as per a 2015-study in adults with influenza A and influenza B infection found out that they both resulted in similar rates of illness and death.

  2. How long does Influenza A last?

    For most healthy people suffering from Influenza A, the flu is somewhat uncomfortable but the illness is short-lived and gets cured on its own. The body’s immune system fights off the virus with symptoms occurring one to four days post exposure to the virus which lasts for five to seven days.

  3. Is influenza contagious after the fever is gone?

    Typically, you stay contagious a day before you observe any symptoms of influenza. The symptoms last for five to seven days after you become sick. So, you remain contagious until the symptoms disappear.


Call 1860-500-1066 to book an appointment.

Verified By Apollo General Physician

Our expert general medicine specialists verify the clinical accuracy of the content to deliver the most trusted source of information, making the management of health an empowering experience.

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