The flu season has started early this year, and we are prepared for it to be a bad one. Whether you have already had a vaccine or are thinking about getting one, here are some answers to the key questions about the jab.

Do I have to pay for the flu vaccine?

In the UK, people who are at a higher risk of becoming severely ill with the flu are prioritised for a free flu vaccine.

This includes people over the age of 65 and those who have weakened immune systems, as well as health and social care workers. It also includes people who are at high risk of passing the virus on to someone vulnerable. If you’re not on this list, you can choose to pay for a flu vaccine at some pharmacies.

Are there any groups who should not get the flu vaccine this year?

The only reason not to get the flu vaccine is if you have had a life-threatening allergy to the ingredients in the vaccine. There are different types of flu vaccines, and some use hens’ eggs in the manufacturing process. If you have an allergy to eggs, let the person giving you the flu vaccine know, as they will make sure you have one that is safe for you.

How long does it take for the flu vaccine to take effect?

The flu vaccine takes about two weeks to reach peak effectiveness.

Why so long? Your immune system needs time to produce the protective antibodies against the influenza viruses in the vaccine.

If I get the flu a few days after the vaccine, is it because I had the flu already?

After you catch the flu virus, it usually hides in your body for a few days before you notice any symptoms. So, it is possible to catch the flu and then get a vaccine without knowing you are infected because you haven’t developed symptoms yet.

If you feel unwell with a fever, you should delay getting your flu jab until you recover. (Getty)

This is just unlucky timing. While it isn’t dangerous, getting the vaccine while you have the flu may make you feel worse. If you do feel unwell with a fever, you should delay getting your flu jab until you recover.

Does a vaccine for a more virulent flu strain make you feel more unwell?

There are a few different types of flu vaccines available, but none of the jabs contain a virus that is able to attack you. Having a vaccine is a bit like showing your immune system a picture of the influenza virus so it knows what to recognise and allows you to have practice at fighting the virus before you catch it from another person.

It is normal to feel a bit unwell for 24 hours after a flu vaccine. Some years, the influenza virus causing infections is more aggressive than normal, but the “picture” of the virus in the vaccine is already weakened, so it won’t cause a stronger reaction.

Does getting COVID boosters around the same time affect the flu vaccine’s effectiveness or the risk of side effects?

Receiving COVID and flu vaccines at the same time is safe, and both vaccines will still be effective. If people develop side effects, they are usually very mild and can include feeling shivery and having a sore arm. This usually lasts less than 24 hours.

There is no good evidence that shows you would be more at risk of side effects by having both vaccines at the same time compared to separately.

About the author

Catherine Wilson is a Clinical Research Fellow in Infectious Diseases and Medical Microbiology at the University of Glasgow.

This article is republished from The Conversation under a Creative Commons licence. Read the original article.

How long does protection typically last, and when is the optimal time to get vaccinated?

The flu vaccine will protect you for about three months. Ideally, you would get the vaccine at the start of winter so you’re protected before you’re exposed to flu. But you also don’t want it too early, or the protection might fade before winter ends. October or November is usually the optimum time for the flu jab.

If I recently had the flu, do I still need the vaccine?

Each winter, there are lots of different strains of flu circulating in the population. The flu jab is what’s called “trivalent”, which means it will protect against three different strains of influenza. If you have already had the flu this winter, it is still a good idea to get your flu vaccine because it will protect you against the other strains.

How does the vaccine work for people with weakened immune systems? Will I still get good protection?

If you have a weakened immune system, you’re at a higher risk of becoming sick with the flu. Usually, a medical condition or specific medications make it harder for your immune system to produce strong antibodies that will successfully attack the flu virus. However, immune suppression exists on a wide spectrum, and most people will still have protection from the flu vaccine despite this.

Getting the flu vaccine protects more than just you (Getty)

If you’re an older adult, your immune response to influenza is often less effective, so you’ll be offered a stronger dose of influenza vaccine to increase your response.

To be on the safe side, it’s important to try to avoid getting the flu in the first place. As well as staying away from people who are unwell and using measures such as face masks, you should encourage your household members and caregivers to also get a flu vaccine. This adds an extra layer of protection for you.

Why should I get vaccinated against the flu this year?

While the flu jab doesn’t stop you catching the flu, it does reduce the chance of you getting very ill. Importantly, it also reduces the chance of you passing the flu on to someone else who is vulnerable.

How do we know what strain of flu the UK is likely to get, and how well does this system work?

The flu virus constantly develops changes in proteins on its surface – the parts that are recognised by our immune systems. All year round, scientists are working together in an international team, coordinated by the World Health Organization, to predict what the virus might look like in time to make vaccines before the flu season starts.

Luckily, flu is seasonal, and not every country experiences seasons at the same time: this gives the scientists a head start. They look at the flu virus that is circulating in the southern hemisphere during winter in June and July – especially in Australia. This gives them an early idea of what the virus might be like when it moves to the northern hemisphere and begins spreading in the UK during our winter.

Information from our flu season this winter will then be used to update the flu vaccine for people in the southern hemisphere before their next winter. This cycle continues every year to try to make the flu vaccine as effective as possible.

This system usually works well, but because there is an element of unpredictability, some years the vaccine isn’t as good a match for the virus as others. Despite this, it is worth getting the vaccine even if it isn’t a perfect match, as it will still protect you from severe disease and from passing the virus on to others, more than if you were unvaccinated.