All your flu and vaccine questions, answered by experts



Published May 23, 2024


Flu season is officially here and the best way to avoid getting sick is to get your flu shot early.

The first flu outbreak was recorded in 1580. Since then, scientists have made huge strides in understanding the flu virus, how it spreads and how to treat it.

But what exactly is the flu? How do flu vaccines work and why do we need a new one every year?

To answer these questions, Medical professor Cheryl Cohen, the Head of the Centre for Respiratory Diseases and Meningitis at the National Institute for Communicable Diseases (NICD), and Dr Noluthando Nematswerani, the Chief Clinical Officer at Discovery Health, explain everything you need to know.

What are the common respiratory viruses circulating at the moment?

Influenza, commonly known as the flu, is a respiratory infection caused by a virus. Symptoms include fever, sore throat, cough, body aches and fatigue.

Another virus currently peaking is Respiratory Syncytial Virus (RSV). RSV affects everyone but is especially dangerous for young children, causing severe illnesses like pneumonia and wheezing.

Covid-19 is also circulating but at lower levels compared to the flu. Although Severe Covid-19 cases still occur, it mainly occurs in vulnerable individuals.

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

Both the common cold and the flu are respiratory illnesses caused by viruses. The common cold usually leads to mild symptoms.

However, the flu can cause severe illness in some individuals and may lead to complications like pneumonia, which might require hospital treatment and can be fatal for some people.

The flu vaccine is safe for children from six months. Picture: cottonbro studio/Pexels

How are respiratory viruses diagnosed?

The most accurate way to identify which respiratory virus is causing an infection is through a swab test analysed in a lab. Many respiratory viruses cause similar symptoms, making it hard to tell them apart without testing.

For most people, symptoms are treated, and they recover within a few days. However, doctors may advise a swab test for patients at high risk of severe illness or those who are very sick.

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

Children under five years old (the flu vaccine is safe for children from six months).

People aged 65 or older.

Individuals living with HIV.

Pregnant women.

Residents of care facilities, such as old-age homes or chronic care institutions.

People with chronic health conditions like asthma, heart or kidney disease, diabetes, and more.

Individuals with weakened immune systems for any reason.

Why should you be vaccinated for the flu?

According to the World Health Organization, flu-related causes result in 290 000 to 650 000 deaths worldwide each year. In South Africa, around 11 000 people die from the flu annually, as reported by the National Institute for Communicable Diseases.

Getting the flu vaccine is the best way to lower your risk of getting the flu. The vaccine is 40% to 60% effective in preventing severe illness in healthy adults. It also reduces the chances of being admitted to an ICU, general hospital, or even dying from the flu.

Health experts urge everyone, especially those in high-risk groups, to get the flu vaccine to protect themselves and others.

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.

Who should avoid getting the flu shot?

Flu vaccines are safe for most people, but there are some exceptions.

Babies under six months old should not get the flu vaccine. Additionally, people who have had a life-threatening allergic reaction to the flu vaccine or its ingredients should avoid it.

People with a severe egg allergy should also not get the flu vaccine, as it is made using chicken eggs and contains a small amount of egg protein.

Those with a rare condition or chronic illness should consult their doctor before getting the flu vaccine. It’s important to seek medical advice to ensure the vaccine is safe for them.

Which type of flu vaccine should I get?

There are two types of flu vaccines available: the quadrivalent influenza vaccine (QIV) and the trivalent influenza vaccine (TIV).

The main difference between them is the number of flu strains they protect against. The trivalent vaccine (TIV) protects against three strains of the flu virus, while the quadrivalent vaccine (QIV) protects against four strains.

The three strains included in the trivalent vaccine are the most common and provide solid protection. Health experts say that both vaccines, QIV and TIV, offer good protection against the flu. Therefore, it does not matter which one you choose to get.

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.

When should you ideally have your flu vaccine?

Flu season typically peaks during the winter months, from June to August. The best time to get the flu vaccine is as soon as it becomes available, usually at the end of March. This early vaccination allows your body to develop antibodies before flu season hits its peak.

However, if you miss this early window, it’s still beneficial to get the flu vaccine as soon as you can. This is especially important for those at high risk of severe flu illness. Getting vaccinated later can still provide good protection against the flu.

Can the flu vaccine give you the flu?

No. The vaccine does not contain any form of live virus, so cannot give you the flu. Some people might experience body aches and inflammation at the injection site for a day or two after receiving the vaccine.

That’s just your immune system reacting to the vaccine, which is perfectly normal.