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A flu shot. For illustrative purposes only. Image Credit: Agency

Dubai: People love the winter season in the UAE. It is also the flu season here, as in most parts of the world.

The flu (short for influenza) season is already underway.

What's peculiar about the flu virus is this: Different strains try to outdo each other to dominate the world (they're sort of like us).

The result: Different strains of flu viruses are always competing to infect — and pass between — people.

Therefore, the virus strains most successful in this "fight" the ones that will become dominant during the "season".

'Severe outbreak'

With health authorities, it becomes like a cat-and-mouse game. Therefore, predicting which of these strains will become dominant in any given season is a key challenge.

And it's a serious one: Flu infections are deadly, killing 36,000 people on average in the US alone each season.

With flu-related deaths already being reported in the current season, experts expect a "severe" flu outbreak.

Here's all you need to know about this viral disease:

Why is it called 'flu season'? When does it begin and end?

The viral infection that seasonal flu brings tends to start spreading in the autumn (September to December) and reaches its peak during the winter months (December to February).

In the UAE, health authorities define the flu season as extending from September to April.

In some places, it can continue even into May and tends to taper off during the summer months. It affects most parts of the world.

What is influenza? What are the types?
Influenza is a contagious viral infection that attacks the respiratory system.

In humans, influenza viruses can be classified into three main groups: A, B, and C.

Type A influenza infection (the strain that attacks birds and some mammals) can be serious and cause widespread outbreaks and disease.

Type A and B viruses cause the large seasonal outbreaks. Type C usually causes milder respiratory symptoms.

What is the strain that the flu vaccine (or flu shot) can be used for?

The flu vaccine (or jab) can help protect you from types A and B.

There is no immunization for type C virus.

In the UAE, the vaccination covers several strains of influenza, including the deadly H1N1 strains, the cause of serious viral infections last flu season.

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Dr Hussain Al Rand addressing the press conference about seasonal influenza vaccine
Influenza Type A, B, C
Type A flu viruses are found in different animals, including ducks, chickens, pigs, whales, horses, and seals.

Type B viruses only affect people.

Type C usually causes milder respiratory symptoms. There is no immunization for type C virus.

How much is a flu shot?

It is free in government clinics for high-risk populations across the UAE, according to the UAE Ministry of Health Prevention.

In private clinics, a flu shot costs Dh50.

Dh50

cost of a flu shot in some private clinics in the UAE. It is free in government clinics for certain high-risk patients.

Where can I get a flu shot?

In the UAE, it is available across in government as well as most private clinics.

Dr Kapil Omprakash Gupta, MD, of Aster Clinic in Dubai, advises people — even those who belong to the non high-risk population — to take the flu vaccine.

"Every year, the jab changes. For the 2019-2020 season, the flu vaccine is now available in all of our clinics as well most private clinics in the UAE," he said.

"When a patient comes, we usually give them information, explaining the advantages. We leave it to the patients to decide on whether to take the shot or not."

What if I don't get the flu shot?

"If you don't get the recommended flu vaccine, then you may be more succeptible to influenza. And if the infection sets in, it will be very severe during this season," said Dr Gupta.

If you don't get the recommended flu vaccine, then you may be more succeptible to influenza. And if the infection sets in, it will be very severe during this season. I took the shot as soon as it was available. My wife, who is also a medical doctor, took it too.

- Dr Kapil Omprakash Gupta, MD, Aster Clinic in Dubai

"I took the shot as soon as it became available. My wife, who is also a medical doctor, took it too. We don't recommend the vaccine to infants less than 6 months old, to those who have allergies to the vaccine, as well as the very sick patients, though," he added.

What is the key benefit of getting the shot?

A flu shot helps your immune system form antibodies against influenza virus, hence curbing your chances of developing the illness and lessenning the transmission of the disease, explained Dr Paz.

Does getting the shot actually prevent flu-related deaths, hospitalisations?

The risk for severe outcomes in adults is cut by more than one-third with a flu shot. In children, the risk for hospitalisation is cut by half, according to the results of two new studies cited by Medscape, a respected medical journal.

The studies were conducted over multiple seasons. The size and rigor of the research give physicians compelling new evidence for vaccine-hesitant patients and parents, said Kristina Bryant, MD, from Norton Children's Hospital and the University of Louisville in Kentucky.

How safe are flu vaccines?

Over the last 50 years, hundreds of millions of people have safely received flu vaccines, affirming the good safety record of the shot. The CDC cites extensive research supporting the safety of flu vaccines.

Dr Wendyliza Paz, of Klinika Maharlika Dubai, explained: "The vaccine complies with WHO recommendation and competent authority decision for the relevant season."

The vaccine complies with WHO recommendation and competent authority decision for the relevant season. An ounce of prevention is always better than a pound of cure.

- Dr Wendyliza Paz, MD, Klinika Maharlika Dubai

"An ounce of prevention is always better than a pound of cure," said Dr Paz. "The best time to take it is before the flu season starts, i.e. September of the current year, until March-April of the following year."

Who should get a flu shot?

Health authorities recommend that everyone 6 months of age and older receive a flu vaccine every year.

"It is an optional vaccine, but it is encouraged, especially for those who have increased risk of developing complications — like pneumonia," said Dr Paz.

According to her, the high-risk population also include:

  • The elderly (65 and above, regardless of their health condition)
  • Infants more 6-months-old onwards
  • Adults and children who have pulmonary and heart problems (including asthmatics)
  • Adults and children with diabetes (or metabolic diseases)
  • Adults and children with chronic kidney problems
  • Ather immuno-deficient patients (i.e. those undergoing chemotheraphy)

What are the most common side effects of a flu shot?

The CDC reports that the most common side effects from the flu shot include:

  • Soreness, redness, and/or swelling from the shot
  • Headache
  • Fever
  • Nausea
  • Muscle aches

How long does immunity from flu shot last?

Protection from influenza vaccine is thought to persist for at least 6 months.

6months

length of the efficacy of influenza vaccine

However, its efficacy declines over time. This is because of two reasons: (a) waning antibody levels and (b) because of changes in circulating influenza viruses from year to year.

In the UAE, the available influenza shot helps prevent all kinds of flu.

Should you take the shot?

Health authorities in the country advise everyone to take thge flu shot to prevent any flu episode.

What causes influenza?  

Influenza is an air-borne virus and can spread through droplets of water released through cough and a runny nose.

Influenza type A virus triggers influenza in birds and some mammals.

Certain strains isolated from influenza A virus cause severe disease in domestic poultry and, in some rare cases, in humans.

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The H5N2 bird flu strain is considered highly contagious. On certain occasions, viruses are transmitted from wild aquatic birds to domestic poultry.

On certain occasions, viruses are transmitted from wild aquatic birds to domestic poultry. This may cause an outbreak or give rise to human influenza pandemics.

What is a pandemic?

According to the WHO, a pandemic is the worldwide spread of a new disease. When a new influenza virus emerges and spreads around the world — for which people do not have immunity — that's when an influenza pandemic occurs.

Historically, viruses that have caused pandemics typically originated from animal influenza viruses.

How come some people recover from a flu infection?

Most cases of the flu resolve on their own.

This happens when the person who gets infected is relatively healthy. However, the flu can become life-threatening if complications — like pneumonia (infection in one or both lungs) — arise alongside it.

Dr Kapil Ompralash Gupta, of Aster Clinic, advises

How does it spread? How contagious is it?

The flu is a highly contagious disease. It spreads when you come into contact with the virus, when someone else sneezes or coughs up.

You could breathe it in.

You could get it on your hands from objects like silverware, doorknobs, handles, television remotes, computer keyboards, and telephones.

The virus enters your body when you touch your hands to your nose, eyes, or mouth.

How many people died from the flu?

For the 2018-2019 US flu season, which started Oct. 1, 2018, and ended May 4 (longest US flu season in a decade), CDC estimates that there were nearly 42.9 million flu cases.

Of this number, up to 647,000 were hospitalised and up to 36,000 died of influenza, making it the seventh-leading cause of death in the US.

36,000

number of influenza-related deaths in the US in the 2018-2019 season, according to CDC data

On September 13, 2019, the first paediatric flu-associated death was already reported in California. In other parts of the globe, it is believed that real-world impact of the flu is being "underreported".

These outbreaks were blamed on the emergence of new strains of influenza viruses that infected people who had no immunity to such strains.

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Break out: Several different flu virus strains emerge in the latter months of the year. Image Credit: AFP

Why are flu and pneumonia usually bundled together?

David Rosenthal, director of Harvard University Health Services, explains: "People don't necessarily die, per se, of the flu virus — the viraemia. What they die of is a secondary pneumonia. So many of these pneumonias are not viral pneumonias but secondary [pneumonias]."

Therefore, experts believe the strong relationship between the flu and pneumonia warrant characterizing them as a single cause of death.

As for the annual death toll, CDC explained: "Typically, influenza causes death when the infection leads to severe medical complications."

The 36,000 "influenza-associated mortality" is an estimate — generated by a CDC modelling method. This number is "a statistical association between deaths and viral data available," explained to William Thompson of the CDC's National Immunization Program (NIP).

WHAT IS AN ANTIGEN?
Antigens are substances (usually proteins) on the surface of cells, viruses, fungi, or bacteria.

Non-living substances such as toxins, chemicals, drugs, and foreign particles (such as a splinter) can also be antigens.

The "antigen" induces an immune response in the body, especially the production of antibodies (also known as an immunoglobulin, or "Ig").

What is H1N1 and all the other flu strains?

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H1N1 or swine flu vaccine is shown at Capital Health Center in Trenton, New Jersey. Image Credit: AP

In general, they are all derivatives or subtypes from the Influenza A virus. Influenza A viruses are negative-sense, single-stranded, segmented RNA (ribonucleic acid) viruses. Negative-strand RNA viruses (NSV) can be further classified into 21 distinct "families".

The several Influenza A subtypes are labeled according to an H number (for the type of hemagglutinin) and an N number (for the type of neuraminidase).

There are 18 different known H antigens (H1 to H18) and 11 different known N antigens (N1 to N11).

What are anti-bodies
An antibody (Ab), also known as an immunoglobulin (Ig), is a large protein produced mainly by plasma cells used by the immune system to neutralise pathogens such as pathogenic bacteria and viruses.

There are five types of antibodies: IgG, IgM, IgA, IgE, IgD.

IgG is the most abundant antibody isotype in the blood (plasma), accounting for 70-75% of human immunoglobulins (antibodies).

H17N10 was isolated from fruit bats in 2012. H18N11 was discovered in a Peruvian bat in 2013. 

The H3N2, the dominant strain in recent years, typically causes more severe disease — and has outpaced other strains over recent weeks, according to the CDC.

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Mohammad Obaid Al Mazroui, Chief of the UAE Haj mission, gets an H1N1 vaccine during a press conference to announce the awareness campaign for the Haj pilgrims. Image Credit: Ravindranath/Gulf News
What is a pathogen?
A pathogen is organism that causes disease in its host. A human pathogen is capable of causing illness in humans.

Once the pathogen sets itself up in a host’s body, it manages to avoid the body’s immune responses. Moreover, it uses the body’s resources to replicate before exiting and spreading to a new host.

Examples pathogenic organisms: Salmonella, Listeria and E. coli, and viruses such as Cryptosporidium.

They can be spread through skin contact, bodily fluids, airborne particles, contact with faeces, and touching a surface touched by an infected person.

Influenza A viruses are negative-sense, single-stranded, segmented RNA (ribonucleic acid) viruses. Negative-strand RNA viruses (NSV) can be further classified into 21 distinct "families".

Cold and flu: What's the difference?

The flu is different from a common cold.

There are 100 different viruses that can cause a cold. On the other hand, only influenza virus types A, B, and C cause the flu. Type A and B viruses cause the large seasonal outbreaks.

Type C usually causes milder respiratory symptoms. The flu vaccine can help protect you from types A and B.

There is no immunization for type C virus.

Type A flu viruses are also found in many different animals, including ducks, chickens, pigs, whales, horses, and seals. Type B viruses only affect people.