Influenza or Flu is a common yet serious contagious viral infection, mainly causing respiratory symptoms. Still “Oh, it is just a flu!” is a common refrain. One important thing to know is not to take Flu (the popular shortform of Influenza) that lightly. Let’s know why.
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Which virus causes Flu?
Influenza virus is an RNA-virus with four types – A, B, C and D. Types A and B are responsible for seasonal flu. Type A is the most important as it causes frequent and widespread outbreaks. Type B is responsible for some small-scale, localized outbreaks, Type C causes minor infections sporadically and Type D is limited to cattle.
Influenza Virus
How does influenza spread?
- Flu is highly contagious and doesn’t spare any age or sex.
- Rainy season and winter are the most likely seasons for it.
- It is spread directly from person to person by air-borne droplets coughed or sneezed out or through sharing things like tissues or handkerchiefs contaminated by the respiratory secretions of the patient.
- After exposure it takes around 1-4 days to manifest.
How to recognize flu? (Signs and symptoms of Influenza)
In adults and older children, the manifestations are pretty much same. Abrupt high fever (102-106*F), chills, flushed face, headache, eye pain, muscle pains, dry cough, cold, sore throat, anorexia and tiredness are the trademark pointers to flu. Diarrhea and vomiting also might occur, especially in children.
In younger children, flu could look like cold, croup, bronchiolitis, bronchitis, middle ear infection or pneumonia. Febrile convulsions are often associated with initial sudden surge of temperature.
In newborns it takes on a different form – a much severe and disguised one. Refusal to feed, lethargy, irritability and apnea (stoppages of breathing) makes it look very similar to bacterial sepsis.
How long does Flu last?
Usually, the fever and pains subside in 4-5 days. Cough and weakness are usually gone by 1-2 weeks but sometimes could last even longer.
Influenza versus Common Cold – What are the differences?
Although commonly ‘Flu’ and ‘Cold’ are often used as words with same meaning, they are very much different. Cold symptoms are much milder, develop gradually and are more localized to nose – (stuffiness, runny nose etc.). Flu on the other hand is much more abrupt, severe and generalized.
Influenza versus Covid – What are the differences?
Clinically Flu and Covid are difficult to differentiate. The loss of taste and smell in Covid is one symptom that is not there in Flu.
Is Influenza really dangerous?
Yes. Following Influenza Statistics should be an eye-opener.
According to WHO, every year there are estimated 1 billion flu cases worldwide, of which 3- 5 million are severe, leading to 290,000 – 600000 deaths.
More than hundred years before the Covid Pandemic that started in 2020, the world was ravaged by an Influenza Pandemic, which started in 1918 and almost continued for seven years. It resulted in approximately100 million deaths. As recently as in 2009, there was a pandemic of Influenza (Type A, H1N1), popularly known as Swine Flu, which was responsible for close to half a million deaths.
What are the Influenza complications?
Pneumonia, dehydration and worsening of existing cardiac or respiratory conditions are common flu complications.
Other important complications include middle ear infection (Otitis media), sinus infection (sinusitis), windpipe infection (Tracheitis), inflammation of muscles (myositis), inflammation of heart (myocarditis), inflammation of brain (encephalitis) and paralysis (Guillain-Barre syndrome).
What are the danger signals in Influenza?
- Continuous bouts of high fever
- Prolonged fever
- Breathing difficulty
- Rapid breathing
- Increasingly noisy breathing
- Ear pain/ discharge
- Lethargy/ drowsiness/ convulsion
- Severe body pains/ headaches
- Explosive diarrhea/ vomiting
- Sick and toxic look
How do we manage it? (What is the treatment of Influenza?)
- Most of the cases need only paracetamol (to control fever and pains), plenty of fluids and rest.
- Vaporization and saline nasal drops/sprays are helpful.
- Ibuprofen can be used under doctor’s guidance.
- Use of diclofenac or other strong anti-inflammatory medicines should be avoided.
- Never use aspirin in young flu patients as it could lead to a serious liver problem called Reye syndrome.
- In severe or complicated cases, antiviral medicines (such as Oseltamivir) may be prescribed by the doctor.
- Antibiotics are unnecessary and useless in uncomplicated flu cases.
How to prevent Influenza?
Handwashing to wash off any infected droplets, avoiding crowded places, avoiding physical contact greetings and not sharing tissues or handkerchiefs are some simple ways to avoid contracting flu.
*It has now been proved that simple hand-wash with soap-water is more effective than the sanitizer solution hand-wash!
- Vaccination against flu is the best way of preventing it. An injectable inactivated flu vaccine and a live attenuated nasal vaccine are most commonly used.
- Injectable flu vaccine can be given to children over the age of 6 months.
- A single injection at the beginning of winter for adults and children above 8 years offers almost 60-80% protection from serious illness and complications.
- When they are receiving it for the first time, children younger than 8 years need 2 doses, which are to be taken at least 1 month apart. The next season onwards, only 1 dose is sufficient.
- The nasal ‘live’ vaccine can be used in healthy children older than 2 years.
How is flu vaccine (Influenza vaccine) different from other vaccines?
Unlike other vaccines that offer a much longer period of immunity, flu vaccine offers only 1-year seasonal protection. This is because of the ability of flu virus to keep changing its antigenic structure regularly.
Influenza virus keeps changing strains through two mechanisms – Antigenic Drift (gradual changes in antigenic structure) and Antigenic Shift (sudden change in antigenic structure). This helps the virus to stay viable over long periods and leads to different strains dominating in different seasons.
The vaccine is prepared every year following the WHO recommendations about which strains of flu virus are going to be more common that year.
Are there any special precautions before and after flu vaccine?
Apart from mild pain, redness at site of injection and occasional mild fever, there are no major side-effects of flu vaccine.
Severe egg-allergy is the only major contra-indication for taking the common injectable inactive influenza vaccine. This is because the preparation of that vaccine involves growing the virus in the egg. There are now egg-free influenza vaccines also available, which are prepared using different technologies.
The live nasal vaccine is contraindicated in individuals with weakened immunity.
What kind of patients do benefit from flu vaccine?
Anybody who wants to avoid flu can opt for the vaccine to get beneficial protection against the prevalent flu strains. American Academy of Pediatrics recommends seasonal flu vaccine for every child above the age of 6 months.
Which are the High-risk groups for Influenza?
Following high-risk individuals should receive Influenza vaccine annually.
- Any chronic heart/lung/kidney/neurologic/blood disease.
- Metabolic diseases like diabetes mellitus and cystic fibrosis.
- Immune deficiency.
- Cancer chemotherapy patients.
- Health care professionals.
- Babies who remain in day-care centers for a significant portion of the working week
- People staying/ working in closed, crowded settings
- Elderly people (over 65 years)
Influenza: Myth versus Reality
| Myth | Reality |
| Flu is a harmless illness. | Flu is a potentially dangerous illness. |
| Antibiotics are necessary in flu-treatment. | Antibiotics are needless and harmful in uncomplicated flu-treatment. |
| Antiviral medicines are necessary for all flu-cases and should be started on our own. | Antiviral medicines are necessary only in certain cases and should be prescribed by a doctor. |
| Sanitizer hand-wash is very useful in prevention of flu. | Simple soap-water hand-wash is more effective in prevention of flu. |
| Flu-vaccine is useless in prevention of flu. | Flu-vaccine is extremely useful in preventing the severe and complicated cases of flu. |
| Giving Flu-vaccine every season is needless. | Flu-vaccine needs to be given every season as the virus types keep changing every season. |
Never take flu lightly. Beneath its common, well-known face a deadly killer is lurking to unleash its fury in full force! Prompt curative measures and prevention whenever appropriate are needed to counter this potentially fatal but extremely common disease.
