The Causes of Influenza – The Primary Causes Explained

Influenza, commonly known as the flu, is an airborne respiratory infection. The causes of influenza are various strains of the influenza virus, which belongs to the family Orthomyxoviridae. These strains are created as the main virus shows high rates of mutations and changes its structure frequently. Humans do not have immunity to the new strains (similar viruses with minor differences) that emerge through such mutations. As a result these recurring processes create pandemics, in which the infection spreads rapidly across continents in a short span of time, causing several deaths and requiring the  hospitalization of many people.

causes of influenza

The type A influenza virus is one of the prime causes of influenza infection.

Causes Of Influenza – The Influenza Virus

The influenza virus is grouped into 3 types – A, B, and C, based on the protein and nucleic acid composition of the virus. Human infection is caused most frequently by the Influenza A type of virus. There are also reports of infection caused by the type B virus, but infection by the type C virus is rare.

Influenza viruses are RNA viruses because their genetic material is RNA. The virus has two protein spikes termed Haemagglutinin (HA) and Neuraminidase (NA). HA plays a major role in the attachment of the virus to human respiratory cells, while NA influences the progression of the infection. 16 HA and 9 NA have been identified till date.

Based on the nature of the HA and NA spikes, influenza viruses are again grouped into various sub types such as H1N1 (Swine Flu), H3N2 (Seasonal Flu), and H5N1 (Bird Flu).

what causes influenza

The reassortment of the influenza virus is what causes influenza in its various forms. The 2009 swine flu pandemic is one such example.

The Source Of The Infection

Wild aquatic birds such as ducks and shore birds are collectively the primary reservoir of the influenza virus. Such birds shed the virus in their excreta, which then acts as the source of infection.The flu virus may mutate and readily jump to species like domestic poultry or swine. The influenza viruses that infect birds and those that infect humans are both capable of infecting pigs. This leads to the mixing up of both the distinct strains, causing an emergence of a new influenza virus which can spread from pigs to humans. This came true during the 2009 H1N1 pandemic, where the pigs acted as the mixing bowl for influenza virus reassortment (mixing up of genes).

The influenza infection is airborne. The virus is transmitted from one person to another  through the air. When an infected individual coughs, sneezes, talks, or spits, the respiratory droplets that carry the virus are exposed to the environment. These viruses then enter the body of another individual through his nose or mouth. Airborne infections can even spread to persons standing up to 6 feet away.

Indirect transmission can also occur in rare cases, when a person’s nose or mouth gets infected by his hands that have already been in contact with contaminated surfaces.

How The Infection Occurs

Once the virus enters a person’s body through his nose, it attaches to the host’s respiratory epithelial cells with the help of the surface protein Haemagglutinin (HA). The virus then travels down the respiratory tract causing much internal damage and finally infects the person’s lungs, leading to pneumonia and bronchitis.

The Life Cycle Of The Influenza Virus Within The Body

Once inside the cells, the influenza virus takes over the host’s body to replicate and produce more viral particles to spread the infection further.

A person infected with influenza sheds the causative virus in his respiratory secretions even before the flu symptoms have manifested. In children, the shedding of the virus can continue for up to 7 days or more.

The Causes Of Influenza – How To Keep The Infection From Spreading

what causes flu

Wear a mask to protect yourself from the influenza virus, which is what causes flu.

If you’ve been infected with influenza, you should take extra care to ensure that you do not unwittingly spread the infection to others. Here are some precautionary measures you can take:

  • Cover your nose and mouth while coughing or sneezing, or wear a mask to cover your nose and mouth at all times during the infection
  • Stay away from your workplace and do not attend any public gatherings when you’re down with the flu. If your child has influenza, do not send him to school or out to play with other kids
  • Wash your hands vigorously with soap and water or with alcohol based hand rubs.

Influenza can cause serious complications and even turn fatal when not diagnosed and treated on time. For this reason, it’s important for you to protect yourself and your family from the causes of influenza, at least by getting the flu vaccine and maintaining high levels of hygiene and sanitation.

Seven Flu Prevention Tips – How to Avoid the Disease

Influenza or the flu is a highly contagious ailment and it can also turn fatal on occasion. Thankfully, it can be prevented by implementing some simple tips. Even though the Center for Disease Control and Prevention (CDC) recommends vaccination as the best flu prevention method, it is not 100 % effective and needs to be supplemented by other preventive measures to protect oneself and others from this infection and control its spread.

flu prevention

Covering your nose and mouth while sneezing or coughing is an important measure for flu prevention.

Flu Prevention – Seven Crucial Tips

  1. Wash Your Hands Properly

    The influenza virus may remain alive outside the human body for 2 – 8 hours and and it is usually transmitted through the hands or the nose of an infected person. This happens either when a patient releases infectious viruses to the surroundings while sneezing or coughing, or touches a door knob or any other objects with his hands after they have been infected by the influenza virus.

    When a healthy individual comes in contact with the contaminated object, he may obtain the infection. For this reason, it is critical to wash hands frequently and rigorously for up to 15 seconds, with soap and water or alcohol based hand sanitizers. Always avoid touching your nose, mouth, or your eyes without washing your hands properly.

  2. Cover Your Mouth And Nose When You Cough Or Sneeze

    Influenza spreads through air, so you must always cover your nose and mouth while sneezing or coughing so as to prevent the influenza virus from being transmitted to your surroundings through respiratory droplets. You can also use tissues instead, but ensure that tissues once used must be properly disposed.

  3. Get The Annual Flu Vaccine

    The most important measure in flu prevention is getting the flu vaccine administered. The flu vaccine can be taken by adults, and children older than 6 months. The vaccine is available as an injection (flu shot) and as a nasal spray (flu mist). The nasal spray vaccine can be taken by children older than 5 years, adolescents, and adults younger than 49 years of age.

    prevention of flu

    The annual flu vaccine is the best method for the prevention of flu, but it is not 100% effective.

    Certain people belong have higher chances of acquiring influenza. These people include:

      • Pregnant women
      • Children younger than 5 years of age
      • Adults older than 65 years of age
      • People with underlying medical conditions like asthma, diabetes, and lung or heart disease
      • Health care workers

    These people who belong to the high risk group should receive the flu vaccination to reduce the severity of complications in case they do contract the flu.

    Influenza viruses are subjected to high mutation rates (change structure frequently) and as a result, no vaccine can give long lasting protection from them. The World Health Organization formulates the flu vaccine every year depending upon the specific strain that is circulating during the flu season.

  4. Stay Away From Crowded Places

    Influenza is highly contagious and spreads easily from person to person. According to CDC, once you catch the flu, you must stay at home till you get well or for at least 24 hours till your fever has subsided without the help of antipyretics (fever reducing medicines). If children have influenza, they must not be sent to school to prevent the spread of the infection. Adults should also stay back from work if they have the flu. It is better for you to avoid crowded places like public gatherings or public transport during peak flu season to lessen the chances of acquiring the infection.

  5. Avoid Close Contact With Infected Individuals

    Avoid close contact with individuals infected with influenza as it increases the risk of acquiring flu. Isolating flu patients reduces the risk of the transmission of the disease, both in hospitals and at home. If coming in contact with an infected individual is inevitable, ensure that you wear a mask of some sort.

  6. Take Preventive Medication

    Drugs are also available for flu prevention. If you’re a health care worker or a caretaker who is in constant contact with flu patients, or a laboratory personnel who deals with flu samples routinely, it is recommended that you take preventive medication. This ensures that your chances of getting the influenza infection are lowered. None of the medicines give long term protection from influenza, but they help in preventing the infection in 70 – 90 % of cases. Preventive medication also helps in preventing flu complications.

  7. Maintain High Levels Of Hygiene

    cold and flu prevention

    Cleaning surfaces with a disinfectant is an important measure for cold and flu prevention.

    It is important to maintain good hygienic practices and take everyday precautions to keep the flu at bay. Here are some basic tips for hygiene:

  • Use disinfectants to clean surfaces and objects as they might be contaminated with the flu virus
  • Avoid spitting on roads
  • Protect your health
  • Manage stress
  • Get a good night’s sleep
  • Exercise regularly
  • Drink lots of water
  • Eat healthy

By following these flu prevention measures, you decrease your chances of being attacked by the flu virus. As influenza is quite infectious and sometimes fatal, your best bet is to prevent the condition instead of fighting its complications at a later date.

The Influenza Vaccine – A Detailed Look at the Preventive Measure

Influenza is an infectious viral disease that can quickly turn complicated, and even fatal. The Advisory Committee on Immunization Practices (ACIP) recommends that the annual influenza vaccine be administered to all people above the age of 6 months. The vaccination should be scheduled before the arrival of the flu season so that there is sufficient time for the body to develop protective antibodies to fight against this dangerous condition. Annual vaccination is the mainstay of preventive measures against influenza.

influenza vaccine

The Live Attenuated Influenza Vaccine comes in the form of a nasal spray.

The Types Of Influenza Vaccine

The Food and Drug Administration (FDA) has licensed two influenza vaccines for use.

  1. The Flu shot (Trivalent Inactivated Influenza Vaccine / TIV)
  2. A Nasal Spray (Live Attenuated Influenza Vaccine / LAIV)

The influenza vaccine is an injectable vaccine that contains a strain of a dead flu virus and it can be administered to anybody older than 6 months. The second type of vaccine contains a live strain of the weakened flu virus (attenuated flu virus) in the form of a nasal spray. It is approved for individuals ranging from 2 years to 49 years of age, except pregnant women. Fluzone, an intradermal influenza vaccine is recommended for adults in the age group of 18 to 64 years.

Within two weeks of vaccination, the body develops antibodies to fight against the flu virus.

The Dosage, Administration, And The Storage Of The Influenza Vaccine

Except the intradermal vaccine, Fluzone, other TIVs should be injected intramuscularly, usually in the arms, and given in one or two doses. The first dose should be given as soon as the vaccine becomes available, to prime the immune system. The second dose, which is administered about four weeks or 28 days after the first dose provides the real protection. TIV is available under different trade names such as Flublok, Flulaval, Fluvirin, Fluarix, Agriflu, Afluria. LIAV is available under the trade name Flumist.

The TIV (injectable) and LIAV (nasal spray) vaccines should be stored at temperatures between 2°C and 8°C, and should not be frozen. LAIV also contains the same formulations as TIV, but is given intranasally. This vaccine is available in a prefilled single-use sprayer container with 0.2 ml of the vaccine. Approximately half of the container (0.1 ml) is administered into one nostril and the second half into the other nostril keeping the recipient in an upright position.

Influenza Vaccine Formulations

The 2012-2013 flu vaccine gives protection against the Influenza A H1N1 2009 pandemic virus, Influenza A H3N2 seasonal strain, and the Influenza type B virus. It is a trivalent (working against three viruses) vaccine formulation.

Influenza viruses undergo constant changes in their structure, as a result of which no vaccine can provide protection from this infection for long. Every year, the World Health Organization (WHO) revises and modifies the formulation of the influenza vaccine according to the influenza virus strain that is circulating in a given geographic area in the specified flu season.

Vaccines should be administered before the flu season, which may start as early as October and reach its peak activity in February. You can get the flu shot administered in clinics, health departments, or pharmacies.

The influenza vaccine is highly recommended for individuals who come under the high risk group, as they are prone to develop serious health conditions related to influenza.

Who Should Be Vaccinated

  • Young children in the age group of 6 months to 5 years of age
  • Adults older than 50 years of age
  • Individuals having health conditions like asthma, diabetes, lung or heart disease, neurologic or hematologic illnesses, or hypertension
  • Individuals with any immuno-compromised condition like pregnancy or HIV infection
  • Those who are taking immunosuppressive drugs
  • Health care workers like laboratory personnel, doctors, and nurses
  • Obese individuals with a Body Mass Index (BMI) of greater than 40
  • Patients undergoing aspirin therapy, who might develop complications due to a flu infection
  • Caretakers of patients having the influenza infection, and others who are in close contact with these patients

Who Should Not Be Vaccinated?

  • Children younger than 6 months old
  • People who are allergic to eggs
  • People who have a history of severe reactions to the influenza vaccine
  • Individuals who suffer from a condition called the Guillian Barré Syndrome, acquired from a  previous influenza vaccination
  • Individuals with a moderate or severe case of the flu, with or without fever
flu shot

Babies under six months of age should not be given the flu shot.

As the influenza vaccine can cause complications when administered to certain people, it is advisable to screen individuals before administering the vaccine, to ensure that the vaccine will not cause the person any harm.

Influenza Vaccine Side Effects

Even though seasonal flu vaccines have very good track records for safety, they can cause adverse effects in some cases. In many cases, mild side effects like nausea, headaches, redness and swelling at the injection site, fever, a runny nose, and muscle aches are observed.

In rare cases, serious adverse reactions like fainting, difficulty in breathing, paleness, and behavioral changes are also reported. If such reactions are observed, the patient should immediately be taken to the doctor. It is a myth that one can get the flu by vaccination, because the viruses in the vaccine are inactivated ones that cannot initiate infection inside the human body.

Getting influenza vaccine shots annually reduces the chances of infection to 60 %, protects you from severe flu-related complications including death, and also reduces the spread of the infection to others. It is considered the best defense against the flu infection.

Influenza Treatment and What It Involves – A Detailed Look

Flu is generally a self-limiting illness and subsides on its own if you take proper rest and drink lots of fluids. But if your flu is caused by a virus that you have no prior immunity towards, you may need to undergo influenza treatment through anti-viral agents (drugs used to treat viral infections).

The Centre for Disease Control and Prevention (CDC) has recommended the Food and Drug Administration (FDA) approved drugs Oseltamivir and Zanamivir for influenza treatment. These drugs can also be taken to prevent influenza too.

Influenza treatment through these drugs should be started within 48 hours of infection for a better clinical outcome. It is ideal to start the treatment as early as possible, and in some cases, doctors recommend the same even without waiting for laboratory confirmation of the disease.

Three Licensed Drugs For Influenza Treatment

These three drugs are recommended for influenza treatment.

Neuramindase Inhibitors Class of Drugs

  1. Oseltamivir (Tamiflu)
  2. Zanamivir (Relenza)

These are the primary anti-viral agents recommended to combat influenza and are active against Influenza A and B type viruses.

influenza treatment

Your physician is likely to prescribe influenza treatment medication like Tamiflu to counter the disease.

The influenza viruses that predominantly cause the disease today don’t have much resistance against these agents. However, there have been reports of Oseltamivir resistance in rare cases and such resistance is common among immuno-suppressed individuals.

Tamiflu is available in the form of capsules (30 mg, 45 mg and 70 mg) and liquid suspensions. It can be taken by children aged 2 years and older.

Zanamivir is not recommended for people with airway diseases such as asthma or chronic obstructive pulmonary disease, and it is available in the form of an inhaler. Zanamivir can be taken by children aged 7 years old and adults.

The Recommended Dosage For Influenza Treatment

Anti-viral medicines are to be taken for five days, and a longer duration may be required for people who are severely ill.


Adults can take 75 mg capsules twice a day. In the case of children, the dosage varies according to the weight as follows:

  • For children aged 1 year (or older) and weigh 15 kg: 30 mg, twice a day
  • For children who weigh around 15-23 kg: 45 mg, twice a day
  • For children who weigh around 23-40 kg: 60 mg, twice a day
  • For children who weigh more than 40 kg: 75 mg, twice a day

Note: The World Health Organization (WHO) has not approved use of Oseltamivir for children who are younger than 2 years of age. The dose mentioned here is authorized for emergency use.


The recommended dosage for this medication is 2 inhalations of 10 mg, twice a day, for children who are 7 years and above, and adults.

Adamantanes Class of Drugs

There are two drugs under this class.

  1. Amantadine (Generic)
  2. Rimantadines (Flumadine)

These drugs are active only against Influenza type A. Reports of widespread resistance for these drugs among Influenza H3N2 and 2009 H1N1 strains have also surfaced, and for this reason, they are not recommended for the currently circulating influenza strains.

The FDA approved dosage of Amantadine for children aged 1-9 yrs is 4.4 – 8.8 mg/kg per day. For children aged 10 years and older, the recommended dosage is 200 mg per day (100 mg twice a day).

The Side Effects Of Anti-flu Medications

Nausea and vomiting are the most common side effects of taking Tamiflu. In rare cases, transient neuropsychiatric changes like self-injury or delirium are also reported.

Zanamivir causes headache, dizziness, nausea, diarrhea, sinusitis, ear, nose and throat infections, bronchitis, and cough. It also causes allergic manifestations like oropharangeal or facial swelling.

The Advantages Of Taking Flu Medications

By regularly taking such medications, you can:

  • Shorten the duration of the illness symptoms
  • Shorten the duration of your hospital stay
  • Reduce the risk of flu related complications like pneumonia, respiratory failure, or death

Who Should Be Given Anti-flu Medications?

  • Any person with confirmed or suspected influenza illness, who is hospitalized
  • Those belonging to high-risk categories such as immune-compromised individuals or people with underlying medical conditions like heart or lung disease, pregnancy, or elderly people and young children
  • Patients with serious flu illness and related complications

Factors That Influence Influenza Treatment

These are some of the factors that dictate the course of treatment to be adopted.

  • Likelihood of influenza infection
  • Clinical judgement based on underlying medical conditions or disease severity and progression
  • Time elapsed since the onset of symptoms
  • Age of the patient
  • Interaction with other medications
  • Indication of treatment – Chemoprophylaxis (preventive measure) or therapy

Influenza Treatment – Treating The Symptoms

  • The fever and body pain associated with influenza can be relieved by pain killers.
  • Pneumonia due to secondary bacterial infection can be treated with antibiotics.
  • Decongestants can reduce discomfort from sinuses, ear infection, and nasal congestion.
  • Gargling a 1:1 ratio of warm water and salt is the best home remedy for sore-throat.
  • Taking anti-histamines helps reduce running nose, and itchy and watery eyes.

It is extremely important to share your medical history with the doctor before trying out the medications for influenza. Underlying medical conditions, pregnancy, old or young age, and allergy to the prescribed drug are some of the factors that influence the outcome of the clinical situation. It is also equally important to take plenty of rest, drink lots of fluids, maintain a balanced diet and stay completely fit during the course of your influenza treatment.

Flu Symptoms in Children – Identifying the Danger Signs

Flu symptoms in children are commonly exhibited during winter, as this is a communicable condition that spreads rapidly, especially among children.

The Reasons Behind Flu Symptoms In Children

School-going children are at high risk of contracting flu as their immune systems (the defense mechanisms of their bodies) are not fully developed. The infection spreads when they mingle with their already-infected classmates, without taking the necessary precautions. Flu symptoms in children typically begin with high fever (sometimes rising above 103 F or 39.4 °C) and are accompanied by chills.

flu symptoms in children

Flu symptoms in children mainly arise due to their underdeveloped immune systems.

About 20000 children of age 5 are hospitalized in the US every year for flu complications.

Common Flu Symptoms In Children (Above 5 Years Of Age)

Apart from the high fever and chills mentioned above, flu comes with symptoms like dry cough, sore throat, headache, fatigue or tiredness, runny nose, and muscle and joint pain. Nausea, diarrhea, and vomiting are also frequently observed.

In addition to these typical flu symptoms in children, some danger signs may be visible, indicating an emergency. They are:

  • Fever
  • Rash
  • Fast breathing
  • Bluish discoloration of the skin
  • A return of symptoms that seemed to have disappeared
  • Irritability
  • Decrease water intake

Common Flu Symptoms In Children (Below 5 Years Of Age)

Children younger than 5 years of age face a high risk of developing complications, including febrile seizures, when infected with the flu. Asthma, diabetes and any other underlying medical conditions also worsen during flu infection.

In younger children (6 months – 5 years of age), the influenza infection pattern resembles the patterns of infections like croup, bronchitis, and pneumonia.

Danger signs in infants include:

  • Lack of tears
  • Less wet diapers than usual
  • Poor intake of food

In infants, there is a danger that signs may go unnoticed, as they are often non-specific.

If the condition is not treated on time, influenza can induce serious complications and turn deadly, even in the healthiest of children. For this reason, parents are advised to pay close attention to flu symptoms in children and consult a doctor immediately in case they notice any.

The Different Types Of Flu – A Quick Look At The Types

Flu, the short form of Influenza (the virus that causes the flu), is one of the most common infections of the respiratory tract (nose, throat, and lungs). There are different types of flu, and some variants like swine flu and bird flu have been featured prominently in the media due to their sudden outbreaks.

types of flu

You can get vaccinated against different types of flu, to protect yourself from the infection.

The symptoms of flu include cough, sore throat, and fever, and the condition can spread easily from one person to another through air. The severity of the disease may range from mild to severe, and the illness sometimes might even lead to the death of the individual.

The Different Types Of Flu – How It Is Classified

Flu, swine flu, bird flu, or seasonal flu are the variations of this disease that you are sure to be familiar with. The Influenza virus can be classified based on the nucleic acid (RNA) and protein (on its outer coat) composition as Type A, B, and C.

Influenza has two protein spikes haemagglutinin (HA) and neuraminidase (NA) in its outer coat and these form the basis for its further classification (into subtypes) as H1N1 or H3N2 etc.

Given below are the three common types of influenza, and how they can distinguished from one another.

Influenza Type A Virus

Type A influenza viruses are the most virulent (extremely infectious) among the three and cause severe disease. Wild aquatic birds are the natural hosts. The virus can also be found in humans, ducks, chickens, pigs, and whales. It causes global outbreaks and was responsible for the 1918, 1957, 1968, and 2009 pandemics (outbreak of global proportions).


Type A viruses have 16 HA (H1-H16) and 9 NA (N1–N9) subtypes that can occur in different combinations and evolve into new strains. For example, the influenza virus that caused the recent 2009 pandemic was H1N1 (Swine Flu). H stands for HA and N for NA and H1N1 is a subtype of the Influenza Type A virus.

Other examples of Type A Influenza viruses are:

• H1N1–1918 1918 (Spanish Flu)

• H2N2 – 1957 (Asian Flu)

• H3N2 – 1968 (Hong Kong Flu)

• H5N1 – 2004 (Bird Flu)

H7N7, H1N2, H9N2, H7N2, H7N3, H10N7 are other Type A viruses. Only H1, H2, H3, N1, and N2 combinations have infected humans till date, but studies have shown that even H7, H9, and H5 combinations can affect humans.

All possible combinations of surface proteins can infect birds. When a subtype that causes an outbreak in birds emerges, it can colloquially obtain the name Bird Flu. Similarly, the types of flu that target swine are commonly christened swine flu.

Influenza type A viruses are unique because they can change their structure very rapidly (high rate of mutation) and can emerge into new viral strains (same but slightly different organisms), bypassing the immune system’s defence mechanism and causing devastating pandemics.

In short, humans are not entirely protected against the new emerging subtypes of Influenza A viruses, and the chances of acquiring an infection are still high.

different types of flu

Bird flu, one of the different types of flu, is caused by the Type A H5N1 virus.

Influenza Type B Virus

Type B viruses are mostly found in humans, but are less common than Type A viruses. These viruses can also infect seal and ferrets.

Among the types of flu, type B viruses cause local epidemics but not pandemics. They also don’t have subtypes like type A viruses. Although these viruses can sometimes cause severe illness, their mutation rate is slow and for this reason, immunity against this type is usually acquired in early life itself. However, there is no long lasting protection against such infections.

Influenza Type C Virus

Influenza Type C viruses are found in humans, pigs, and dogs. These viruses are less common and cause mild cold-like illness.

Structural Differences Between The Types Of Flu

Basically, the three types of flu have almost similar structures – so much so that it’s hard to distinguish between type A and B viruses even with an electron microscope. Some notable differences between the types have been given below.


Type A: Has three membrane proteins, namely HA, NA, and M2, a matrix protein M1, ribonucleoprotein core (with PA, PB1 and PB2), and NEP/ NS2 proteins.

Type B: Has four envelope proteins HA, NA, NB, and BM2.

Type C: Has HEF protein (haemagglutinin-esterase-fusion protein), which has the functions of HA and NA. It has CM2 as the viral envelop protein.

Ribonucleic Acid (RNA)

Type A: RNA has 8 segments

Type B: RNA has 8 segments

Type C: RNA has 7 segments

People often get confused and use the term “flu” for any respiratory illness that is caused by a virus. By learning about the types of flu, you’ll find it easier to identify the type of infection and choose the relevant treatment.

Five Key Influenza Symptoms – Spotting The Flu

Influenza, commonly known as the flu, is a highly contagious respiratory illness that affects the nose, throat, and lungs. When an infected patient coughs or sneezes, the influenza virus is expelled through his mouth and nose. It travels through the air, spreading the infection from person to person, causing mild to severe cases of influenza symptoms.

influenza symptoms

The sudden onset of high fever is one of the key influenza symptoms.

The period between the infection and the start of the illness, termed as the incubation period, usually lasts for a couple of days. The patient is highly infectious during this period, as he keeps shedding the virus in respiratory droplets, which in turn can spread the disease.

Most patients contract a relatively mild form of the illness and recover in the span of a few days to around two weeks, but sometimes, the flu can turn fatal.

Influenza Symptoms – Five Key Ones To Look Out For

These are the five key influenza symptoms that you need to watch out for.

  • The sudden onset of high fever (sometimes rising above 103 F or 39.4 °C) with chills
  • Dry cough
  • Sore throat
  • Headaches
  • Fatigue or tiredness
  • A runny nose
  • Body aches in the form of muscle and joint pain

Patients might also experience:

  • Malaise
  • Redness and a burning sensation in the eyes
  • Vomiting and diarrhea (common in children)

Clarifying Influenza Symptoms – Is It Just A Cold Or The Flu?

People often confuse the flu with the common cold, but certain symptoms of the flu can help in differentiating this condition from the common cold. These are:

  • Its sudden onset
  • The presence of fever and chills
  • Discomfort in the chest
  • Body aches, which are often mild or absent in a person having a common cold

The Complications Of Influenza

Pneumonia, bronchitis, sinusitis, ear infections, and dehydration are some of the complications of an influenza infection.

The flu may even worsen existing medical conditions such as asthma, congestive heart failure, or diabetes.

Susceptibility To Influenza Symptoms

The following people are more susceptible to the infection and may experience mild or severe influenza symptoms.

  • Children less than two years of age
  • Adults aged 65 and above
  • People with compromised immune systems, such as those who have chronic diseases related to the heart, lungs, kidneys, liver, blood, or the metabolism

Identifying Severe Influenza Symptoms

A person experiencing any of the following influenza symptoms must be rushed to the doctor immediately, as these signify that the condition is severe.

  • Difficulty in breathing
  • Chest pain
  • Abdominal pressure
  • Dizziness
  • Seizures
  • Rashes
  • Confusion
  • Persistent vomiting
  • A bluish tinge on the lips and skin

Influenza symptoms in infants include a lack of tears while crying, fewer wet diapers, and lesser food intake than usual.

Adults may experience a slight improvement in the condition and a subsequent return of the symptoms including fever and a cough characterized by a yellowish green mucus.

Some young children and teenagers may develop a condition called Reye’s syndrome after recovering from the flu. This condition begins with nausea and vomiting, and gradually affects the nerves, bringing about progressive mental changes such as confusion or delirium.

In people who harbor strong immunity to the influenza virus, influenza may present itself as a mild cold. But even in their case, the infection can turn fatal if the flu-causing virus belongs to a newly emergent strain to which they are not immune.

Consulting a doctor as soon as influenza symptoms appear is highly recommended. Otherwise, this seemingly mild disease has the potential to turn fatal.

Influenza Vaccine Side Effects – What You Should Know

Influenza vaccine side effects are quite mild as the vaccines have a good track record for safety. These side effects can be resolved quickly and without extensive treatment too, as they cause serious repercussions only in very rare cases.

Learning about such influenza vaccine side effects can help you be prepared for what you might face.

influenza vaccine side effects

Influenza vaccine side effects can turn complicated occasionally

Trivalent Inactivated Influenza Vaccine Side Effects

Minor side effects caused by the Trivalent Inactivated Influenza Vaccine (TIV) can be spotted as soon as the vaccine is administered, and they usually last for a day or two. They include:

  • Soreness, pain, redness, and swelling at the site of injection (10-64% of cases)
  • Low grade fever
  • Malaise (muscle pain and weakness)
  • Nausea
  • Headache
  • Body aches
  • Fainting, mainly in adolescents

Live Attenuated Influenza Vaccine Side effects

Mild side effects that result from the Live Attenuated Influenza Vaccine (LAIV) include:

  • Runny nose
  • Nasal congestion
  • Mild wheezing
  • Headaches
  • Vomiting
  • Muscle aches
  • Fever > 100 F and chills
  • Cough
  • A sore throat
  • Sinusitis
  • Weakness/Tiredness

Influenza Vaccine Side Effects – Some Adverse Results

Influenza vaccine side effects can occasionally include some serious conditions, such as:

  • Allergic reactions to vaccine components
  • Redness and swelling of the eyes
  • Respiratory symptoms like cough and hoarseness of the voice (reported within 24 hours of vaccination)
  • Febrile seizures or fits
  • Difficulty in breathing
  • Swelling around the lips
  • Behavioral changes
  • Paleness and weakness
  • Heart palpitations
  • Guillain Barre Syndrome, a serious neurological syndrome that can lead to paralysis

If you observe any of these signs, consult a doctor immediately, as they indicate a need for serious medical attention.

What You Should Know About Influenza Vaccine Side Effects

Be extremely careful before taking the flu vaccine. People who have a prior history of adverse reactions towards the influenza vaccine or people who are allergic to the vaccine’s components (like eggs) should avoid the influenza vaccine.

Also, the injectable flu vaccine must not be administered to children younger than 6 months of age, and the nasal spray flu vaccine is not recommended for children below two years of age. It is also important for clinicians to follow the right technique while administering the flu vaccine.

The Vaccine Adverse Event Reporting System

Any adverse reaction caused by the flu vaccine should be reported to the Vaccine Adverse Event Reporting System (VAERS), a surveillance system co-sponsored by the Center for Disease Control and Prevention.

It must also be reported to the Food and Drug Administration, which monitors vaccine safety and helps in further investigating the harmful side effect.

Vaccine Injury Compensation Program

Individuals who have had an adverse reaction following the process of vaccination are entitled to compensation from the Vaccine Injury Compensation Program (VICP), which is a federal program.

It is important to note that there is no substance behind the myth that a person can contract the flu through the flu vaccine. This is because the viruses used in the preparation of the vaccine are inactive and cannot multiply in the lungs or cause an infection.

If you are planning to protect yourself against influenza, being aware of the influenza vaccine side effects can turn out to be highly useful.