Overview of Influenza

Influenza or flu (وبائی زکام) is one of the common infectious diseases caused by viruses. Influenza virus attacks the cells of your respiratory system (nose, throat, and lungs). Influenza is also known as flu, but it is different from stomach flu that causes digestive problems such as diarrhoea and vomiting.

Typically, the route of transmission of the influenza virus is air. In the air, it is spread from coughs or sneezes. This happens over relatively short distances. Influenza virus can also spread by touching surfaces contaminated by the virus. The virus then enters the body through the eyes, nose, or mouth upon touch. A person can be infectious both before and during the time symptoms appear.  Influenza can be confirmed by testing the samples from the throat, sputum, or nose. 

Occurrence of Influenza

The impacts of seasonal influenza epidemics in developing countries are not completely known. However, as per studies, 99% of deaths in children under age 5 are due to influenza-related lower respiratory tract infections. People who most likely develop influenza-related complications are 

  • Pregnant women 
  • The elderly
  • Children under 59 months 
  • Individuals with chronic illnesses
  • People with immunosuppressive conditions such as AIDS or receiving chemotherapy in the past

Since 2009, Pakistan gets seasonal flu every year, which peaks in January and February. Mostly, positive cases have been recorded in Rawalpindi, Islamabad, Multan, Peshawar, Sargodha, and Karachi with an increased mortality rate.

The Influenza Pandemic

The influenza pandemic of 1918-1919 is considered the greatest pandemic or global disaster. This pandemic killed more people than World War I. the effect of this pandemic was so drastic that the life span in the US was depressed by 10 years. This outbreak covers a large part of North America, Europe, Asia, and Africa.

Doctors Treating Influenza

677 Doctors Available

Signs and Symptoms of Influenza

At the initial stages, flu symptoms may appear like common colds such as sneezing, runny nose, and sore throat. However, the cold's progression is slow but the flu develops suddenly. Though cold bothers you but flu symptoms are far worse.  

Common signs and symptoms of the flu are:

  • Fever
  • Sore throat
  • Aching muscles
  • Tiredness and weakness
  • Eye pain
  • Chills and sweats
  • Headache
  • Dry, persistent cough
  • Shortness of breath
  • Runny or stuffy nose
  • Vomiting and diarrhea, but this is more common in children than in adults

Types of Influenza

Depending upon the severity of influenza it is divided into three types which are as follows:

Influenza virus A

  • Infect animals, wild birds act as the host
  • Constantly changing
  • Cause large flu epidemics

Influenza virus B

  • Infect only humans
  • Milder than type A
  • Do not cause a pandemic

Influenza virus C

  • Infect only human
  • Milder than A and B
  • Do not cause a pandemic

Causes of Influenza

Influenza is a contagious infection and causes of influenza spread are:

Contagious Infection

Influenza viruses transfer in air droplets from an infectious person to a normal one during coughing, sneezing, or talking.

The virus can enter inside your body either by inhaling droplets or touching contaminated objects. The virus transfers through your hands to the eyes, nose, or mouth.

When a virus enters your body, you may become contagious one day before symptoms appear. Children and people with weak immunity may become contagious for a longer time.

Strain Variation

Strain variation is changing the influenza virus with new strains appearing regularly. Exposure to the virus makes you immune to infection in the future. This happens because your body develops antibodies specific to the virus.

When the infection recurs, the already present antibodies recognize the virus and prevent the infection. However, antibody levels may decline over time. But, if strain variation occurs and a new strain causes infection, antibodies may be not able to prevent infection.


Risk Factors of Influenza

Most of the time influenza is resolved on its own but sometimes the condition becomes complicated and deadly. People who are most likely to develop flu complications are:

  • Children under age 5 especially toddlers
  • Adults above 65 years
  • Nursing home residents 
  • People with weakened immune systems
  • Pregnant women and women up to two weeks after giving birth
  • People suffering from chronic illnesses, such as asthma, heart disease, kidney disease, liver disease, and diabetes
  • Obesity i.e. Obese people with a body mass index (BMI) of 40 or higher
  • Native Americans

Health-Related Complications of Influenza

The flu is not a serious problem in young and healthy people. However, children and adults with the weak immune system are most likely to develop complications such as: 

Acute Respiratory Distress Syndrome

Pneumonia is the most complicated form of flu. For older adults and people with a serious disease, pneumonia can be life-threatening. As per the Centers for Disease Control and Prevention (CDC) recommendation, every child below age 6 or older needs to be vaccinated every year. The vaccine reduces the risk of developing flu and other severe illnesses.

This season flu vaccination is most important because both flu and coronavirus 2019 cause the same symptoms. Prevention of flu and decreasing the severity of flu can reduce the number of people admitted to the hospital.

Seasonal flu vaccine may protect you from all the types of influenza viruses that are expected to cause flu during flu season. The vaccine is available both in injection and nasal form. The nasal vaccine is not recommended for:

  • Certain age groups
  • Pregnant women
  • People having asthma, and weak immune systems 



Some of the best preventive measures against influenza are as follows:

  1. If you are sick, stay at home
  2. Make sure to wear a mask 
  3. Maintain a safe distance from sick people 
  4. Pay special attention to personal hygiene 
  5. Do not touch your eyes, nose, or mouth too much 
  6. Make healthy lifestyle changes


During flu season your doctor may suggest you test for diagnosis of influenza. Healthcare may diagnose you on the basis of your signs and symptoms.

  • For the diagnosis of influenza, various tests are performed. Polymerase Chain Reaction (PCR) is one of the most common tests used in diagnostic labs. This test is more sensitive and specific than other tests. It can be performed both in the doctor’s office and the hospital.

Treatment of Influenza | When to Consult a Doctor

Influenza is treated in various ways. Let’s have a look at how influenza is treated.

1. Natural Remedies

You can ease your symptoms by using some natural remedies such as: 

  • Drink Plenty of Water: To avoid dehydration drink water, juices, and warm soups.
  • Rest: Get a good sleep for at least 8 hours, because during sleep your immune system is boosted up and fights against infections. Also, try to change your daily routine.

2. Medications

  • Oseltamivir (Tamiflu)---oral medication
  • Zanamivir (Relenza)---inhaled through an asthma inhaler
  • Peramivir (Rapivab) 
  • Baloxavir (Xofluza) 

Side Effects of Antiviral Drugs:

  • Nausea
  • Vomiting

These side effects can be avoided by taking medicines with food. 

*amantadine and rimantadine (Flumadine) are no longer recommended because the influenza virus has developed resistance against the. 

However, influenza recovers itself after a certain period of time. But if you are above 65 years of age, have chronic illnesses (asthma, heart problem, or diabetes) or a weak immune system, and experience serious signs and symptoms such as fever above 100 F, cough, headache, and vomiting seek immediate medical care.

Control of Infection Spread

The spread of the influenza virus can be prevented by following some precautions including:

  • Frequent Hand Washing: Wash your hands properly with soap and water for at least 20 seconds. You can also use alcohol hand sanitizers in absence of soap and water. Proper handwashing can protect you from various infectious diseases.
  • Cover Your Coughs and Sneezes: Cover your mouth with a tissue or your elbow while coughing or sneezing. And after this wash your hands properly.
  • Avoid Touching Your Face: Don’t touch your face, especially your eyes, nose, and mouth. Because they are the main routes through which the virus can enter your respiratory system.
  • Disinfect Surfaces. The virus can also spread from surfaces upon touch. Try to disinfect the surfaces which are frequently touched.
  • Avoid Gatherings: In gatherings, there are more chances of virus spread such as in child care centers, schools, office buildings, auditoriums, and public transportation. You can reduce the chances of developing flu by avoiding these crowded places in the peak flu season.
  • Avoid Sick People: Avoid meeting and especially making contact with sick people. Similarly, if you are sick try to stay at home. This way you not only recover rapidly but also prevent the spread of infection.

Influenza Virus Vaccine

  • Flu Shot: The flu shot is usually given to children six months and older. It is an inactive vaccine that is prepared by using a dead virus. To people aged between 18-64, it is given intradermally. These vaccines are safe for those people who are allergic to eggs.
  • Fluzone High Dose: This inactivated vaccine is for older people (65 and above) because they have a weak immune system.
  • Egg-free Vaccines: these vaccines can give to people having egg allergies because they are prepared inside eggs.
  • Nasal Spray: It is a live attenuated vaccine also known as LAIV. It is prepared from live but attenuated influenza virus. However, it does not cause the flu. It is recommended for healthy and non-pregnant people.

Because virus strains are constantly changing, therefore scientists develop a new vaccine each year for the new strain. 

Influenza Vaccine Side Effects

Influenza vaccines also have side effects like other medicines. But the risks are not harmful or deadly.

Some common side effects caused by flu shots and nasal sprays are:

  • Mild fever
  • Soreness, redness, or swelling at the shot side
  • Muscle aches

Side effects of the nasal spray flu vaccine may include:

  • Cough
  • Sore throat
  • Headache, muscle aches
  • Runny nose, nasal congestion

Sometimes people may develop severe allergic reactions against the vaccine. Some of the common signs and symptoms of a severe allergic reaction are:

  • Mood changes
  • Vertigo
  • Hives
  • Hoarse voice
  • High fever
  • Weakness
  • Breathing difficulty
  • Pale skin
  • Rapid heartbeat

In case of any concerning signs and symptoms, you need to consult a medical healthcare specialist as soon as possible.