Your questions about the flu and flu vaccine, answered

By Professor Cheryl Cohen, Head of the Centre for Respiratory Diseases and Meningitis at the National Institute for Communicable Diseases (NICD), and Dr Noluthando Nematswerani, Chief Clinical Officer at Discovery Health

Flu season is officially here. The best way to protect yourself from a nasty bout of flu is by getting your flu vaccination early.

The first recorded influenza outbreak happened in 1580. We've come a long way since then in understanding influenza viruses, how they work, and how to treat them. But what exactly is the flu?

How does the flu vaccine help us, and why do we need a new vaccine each year? Here's what you need to know.

1. What are the common respiratory viruses circulating at the moment?

Flu (short for 'influenza') is a respiratory infection caused by an influenza virus. Symptoms of the flu include fever, sore throat, cough, body aches and fatigue.

Another virus is the respiratory syncytial virus (RSV). This virus can affect anyone, especially young children, often causing severe illness and complications like pneumonia and wheezing.

COVID-19 continues to circulate but at a lower level than flu. Severe cases of COVID-19 still occur, especially in people who are vulnerable.

2. What is the difference between a common cold and the flu?

Both are respiratory illnesses caused by viruses. The common cold usually causes mild illness. However, the flu can cause severe illness and complications like pneumonia, which may require hospital treatment and can be fatal for some people.

3. How are respiratory viruses diagnosed?

A swab analysed in a laboratory is the best way to identify which respiratory virus a person has. There is a lot of overlap in symptoms caused by various respiratory viruses. In most cases, the patient's symptoms are treated, and they get better within a few days. Doctors may recommend a swab test for patients at high risk of severe illness or those who are very sick.

4. Who is at high risk of becoming seriously ill from the flu?

The following groups of people are at high risk of becoming seriously ill from the flu:

• Children up to age five. Keep in mind that the flu vaccine is considered safe for children from six months old onwards.
• People aged 65 or older.
• People living with HIV.
• Women who are pregnant or who've had a baby within the past six weeks. Note that the flu vaccine is safe to get while breastfeeding.
• People living in care facilities (old-age homes or chronic care and rehabilitation institutions).
• People with chronic health conditions (for example, chronic lung diseases like asthma, heart or kidney disease, diabetes).
• People with weakened immune systems for whatever reason.

5. Why should you be vaccinated against the flu?

Getting the flu vaccine is the best way to lower your risk of becoming sick with flu. Flu vaccines are about 40% to 60% effective in preventing severe flu illness in healthy adults. They also reduce the risk of admission to an intensive care unit (ICU), general hospitalisation and death.

The World Health Organization reports that 290,000 to 650,000 people die of flu-related causes every year worldwide. In South Africa, the flu kills about 11,000 people every year, according to the National Institute for Communicable Diseases.

6. Do you really need to get a flu vaccination every year?

Yes. Flu viruses change quickly. The vaccines are made to match each year's new flu variants as closely as possible.

7. Who should avoid getting the flu vaccine?

Most people should get a flu vaccination every season, but there are a few exceptions.

• Babies under six months old should not get the vaccine.
• People who have had a life-threatening allergic reaction to the flu vaccine or any of its ingredients should avoid the flu vaccine. Those with a severe egg allergy should also avoid it as it is manufactured with chicken eggs and contains a small amount of egg protein.
• It is also advisable for patients with a rare condition or chronic illness to consult with their doctor before getting the flu vaccine.

8. There are two types of flu vaccine - a quadrivalent influenza vaccine (QIV) and a trivalent vaccine (TIV). What is the difference between them, and which one should you take?

The trivalent vaccine protects against three strains of the influenza virus, while the quadrivalent vaccine protects against four strains. The three strains of influenza remain the most common ones we should be protecting ourselves against. Medical professionals recommend either the QIV or TIV vaccine as both offer good protection against the flu, so it does not matter which one you get.

9. How long does it take for the flu vaccine to be effective once administered?

It takes your body around one to two weeks to develop antibodies against the flu after receiving the flu vaccine. This means that if you get the flu vaccine today and are infected with the flu tomorrow, you are not yet protected by your vaccine.

10. When should you ideally get your flu vaccination?

Flu season usually peaks in the winter months between June and August. The best time to get the flu vaccine is as soon as it becomes available, which is normally at the end of March. This timing gives your body time to develop antibodies against the flu before the flu season reaches its peak.

But if you miss that window, getting vaccinated as soon as you're able to will still give you good protection against the flu - especially if you are at high risk of severe flu illness.

11. Can the flu vaccine give you the flu?

No. The vaccine does not contain any form of live virus, so it cannot give you flu. Some people might experience body aches and inflammation at the injection site for a day or two after getting the vaccine. That's just your immune system reacting to the vaccine, which is perfectly normal.

12. Which non-pharmaceutical interventions can people practise to limit the spread of the virus?

• Stay indoors if you are feeling sick, to limit contact with people.
• Wash your hands frequently if you are coughing or sneezing, or exposed to people who are ill.
• Use a disposable tissues, or cough or sneeze into your flexed your elbow.
• If you feel sick, wear a mask to limit spreading viruses to others.

Last year, Dr Noluthando engaged in an enlightening conversation on this topic with Professor Cheryl Cohen, Associate Professor in Epidemiology at Wits University and Head of the Centre for Respiratory Diseases and Meningitis at the National Institute for Communicable Diseases.

Note this: Watch the 14-minute YouTube video.