About Influenza (Flu)
What is Influenza (Flu)?
Seasonal influenza (or “flu”) is most often caused by type A or B influenza viruses. Symptoms include sudden onset of fever, cough (usually dry), headache, muscle and joint pain, sore throat and a runny nose. The cough can be severe and can last 2 or more weeks. Most people recover from fever and other symptoms within a week without requiring medical attention. However, influenza can cause severe illness or death in high-risk groups
The best way to prevent flu is by getting a flu vaccine each year.
When is flu season?
Seasonal epidemics occur mainly during winter, from October to March in the northern hemisphere and April to September in the southern hemisphere. In tropical and subtropical countries, seasonal influenza can happen all year round.
What are the symptoms of flu?
Influenza can cause mild to severe illness, and at times can lead to death. Flu is different from a cold. Flu usually comes on suddenly. People who have flu often feel some or all of these symptoms:
- Fever/feeling feverish/chills
- sore throat
- runny or stuffy nose
- muscle or body aches
- fatigue (tiredness)
- some people may have vomiting and diarrhoea, though this is more common in children than adults.
It is important to note that not everyone with flu will have a fever. Most people who get flu will recover in a few days to less than two weeks, but some people will develop complications (such as pneumonia) as a result of flu, some of which can be life-threatening.
For more information on the flu symptoms and complications visit the Centers for Disease Control and Prevention (CDCP) website.
Is flu contagious?
Yes. Flu is most contagious in the first 3 to 4 days after the illness begins. Most healthy adults can infect others beginning 1 day before symptoms develop and up to 5 to 7 days after becoming sick. Children and some people with weakened immune systems may pass the virus for longer than 7 days. Symptoms can begin about 2 days (but can range from 1 to 4 days) after the virus enters the body. That means that you may be able to pass on the flu to someone else before you know you are sick, as well as while you are sick. Some people can be infected with the flu virus but have no symptoms. During this time, those people may still spread the virus to others.
How is flu spread?
It can spread from person to person up to 6 feet away and is spread mainly by droplets from people with flu, who cough, sneeze or talk. These droplets can land in the mouths or noses of people who are nearby or possibly be inhaled into the lungs. Less often, a person might get flu by touching a surface or object that has flu virus on it and then touching their own mouth, nose, or possibly their eyes.
How long is flu contagious for?
It is possible to pass on flu to someone else before you know you are sick, as well as while you are sick.
- People with flu are most contagious in the first 3-4 days after their illness begins.
- Some otherwise healthy adults may be able to infect others beginning 1 day before symptoms develop and up to 5 to 7 days after becoming sick.
- Some people, especially young children, and people with weakened immune systems, might be able to infect others with flu viruses for an even longer time.
Why have we not heard much about the flu recently?
Flu activity remains unusually low this year, largely in part to all the restrictions put in place for COVID-19. However, even though flu activity is low, the flu is still out there and could surge at any moment. Having a flu vaccination is so important to ensure those at risk are properly protected.
Can wearing a mask and social distancing protect against the flu?
Wearing a mask and social distancing can help protect you and others from respiratory viruses, like flu and COVID-19, but the best way to prevent flu illness is for everyone 6 months and older to be vaccinated each year.
Why should people get vaccinated against flu?
Influenza is a potentially serious disease. Every flu season is different, and influenza infection can affect people differently, but globally, millions of people get flu every year, hundreds of thousands of people are hospitalised and thousands to tens of thousands of people die from flu-related causes every year. An annual seasonal flu vaccine is the best way to help protect against flu.
Who is most at risk of catching the flu?
People most at risk of catching seasonal influenza are:
- pregnant women at any stage of pregnancy
- children younger than 5 years
- people older than 65 years
- people with chronic medical conditions such as HIV/AIDS, asthma, heart and lung diseases and diabetes
- people with increased risk of exposure to influenza, which includes health care workers.
For a more detailed list see: https://www.cdc.gov/flu/highrisk/index.htm
Who should get the flu vaccine?
The flu vaccine is recommend to people who:
- are 50 and over.
- have certain health conditions.
- are pregnant.
- are in long-stay residential care.
- receive a carer’s allowance or are the main carer for an older or disabled person who may be at risk if you get sick.
- live with someone who is at high risk from coronavirus
- frontline health or social care workers
Why should my child get vaccinated?
Flu illness is more dangerous than the common cold for children. Each year, millions of children get sick with seasonal flu; thousands of children are hospitalised, and some children die from flu. Children commonly need medical care because of flu, especially children younger than 5 years old.
You can find more details about this on the Center for Disease Control and Prevention (CDCP) website.
Why is getting a flu vaccine important for older people?
With an immune system weaker than when they were younger, seniors are more susceptible to catching the flu. They are also likely to take longer to recover and more vulnerable to complications. Flu prevention is vital for keeping them safe during the cold winter months.
Why is getting a flu vaccine important for pregnant women?
The immune system is weakened during pregnancy, making pregnant women less able to fight off the flu. It passing to their unborn baby could lead to lower birth weight, premature birth or a miscarriage. Both mum and baby alike can benefit from flu prevention to keep them healthy.
Why is getting a flu vaccine important for people with chronic health conditions?
The flu hits people with chronic medical conditions twice as hard. Not only are they more susceptible to catching the flu and vulnerable to severe flu, but the flu virus may make their existing condition worse. Preventing the flu is vital for keeping them well during the flu season.
Who should not get vaccinated?
Children younger than 6 months of age are too young to get a flu shot. Most adults can have the flu vaccine, but you should avoid it if you have had a serious allergic reaction to a flu vaccine in the past. You may be at risk of an allergic reaction to the flu vaccine injection if you have an egg allergy. This is because some flu vaccines are made using eggs. Ask your doctor for a low-egg or egg-free vaccine. Also, if you are ill with a high temperature, it is best to wait until you are better before having the flu vaccine.
Why do I need a flu vaccine every year?
A flu vaccine is needed every year for two reasons. First, a person’s immune protection from vaccination declines over time, so an annual vaccine is needed for optimal protection. Second, because flu viruses are constantly changing, flu vaccines may be updated from one season to the next to protect against the viruses that research suggests may be most common during the upcoming flu season. For the best protection, everyone 6 months and older should get vaccinated annually.
When should you have your flu vaccine?
In the Northern Hemisphere, the flu season can begin as early as October and can last as late as April or May. In the temperate regions of the Southern Hemisphere, influenza activity typically occurs during April – September. In the tropics, influenza activity occurs throughout the year.
Most countries in the Northern Hemisphere start immunisation in the early autumn. The immune response already starts to develop after a few days and gradually increases the level of protection it provides, reaching its maximum by 14 days.
How do flu vaccines work?
Flu vaccines cause antibodies to develop in the body about two weeks after vaccination. These antibodies provide protection against infection with the viruses that are used to make the vaccine.
The seasonal flu vaccine protects against the influenza viruses that research indicates will be most common during the upcoming season. Most flu vaccines protect against four different flu viruses (“quadrivalent”); an influenza A (H1N1) virus, an influenza A (H3N2) virus, and two influenza B viruses. There are also some flu vaccines that protect against three different flu viruses (“trivalent”); an influenza A (H1N1) virus, an influenza A (H3N2) virus, and one influenza B virus. Two of the trivalent vaccines are designed specifically for people 65 and older to create a stronger immune response.
Does a flu vaccine work right away?
No. It takes about two weeks after vaccination for antibodies to develop in the body and provide protection against influenza virus infection. That is why it is best to get vaccinated before influenza viruses start to spread in your community.
What ingredients are in the flu vaccine?
There are several types of injected flu vaccine that contain a variety of ingredients. None of them contains live viruses so they cannot give you flu. You will be offered one that is most effective for you, depending on your age.
For more information see guidance by the World Health Organization (WHO) recommended composition of influenza virus vaccines for use in the 2021 – 2022 in the northern hemisphere influenza season.
What are the flu vaccine side effects?
Flu vaccines are safe. All adult flu vaccines are given by injection into the muscle of the upper arm.
Most side effects are mild and only last for a day or so, such as:
- slightly raised temperature.
- muscle aches
- sore arm where the needle went in – this is more likely to happen with the vaccine for people aged 65 and over.
However, to reduce discomfort try to move your arm regularly or take a painkiller, such as paracetamol or ibuprofen – although, some people, including those who are pregnant, should not take ibuprofen unless a doctor recommends it.
About Influenza and COVID-19
Are COVID-19 and Influenza similar?
There are similarities; they both cause respiratory disease, which presents as a wide range of illness from asymptomatic or mild through to severe disease and death.
Secondly, both viruses are transmitted by contact, droplets and objects or materials which are likely to carry infection, such as clothes, utensils, and furniture. As a result, the same public health measures to prevent infection, such as hand hygiene and good respiratory etiquette (coughing into your elbow or into a tissue and immediately disposing of the tissue), are important actions in preventing infection.
How do I tell the difference between Influenza (Flu) and COVID-19?
While they are both contagious respiratory illnesses, they are caused by different viruses. COVID-19 is caused by infection with a new coronavirus (called SARS-CoV-2) and flu is caused by infection with influenza viruses. But the speed of transmission is an important difference between the two viruses. Influenza has a shorter median incubation period (the time from infection to appearance of symptoms) and a shorter serial interval (the time between successive cases) than COVID-19 virus. The serial interval for COVID-19 virus is estimated to be 5-6 days, while for influenza virus, the serial interval is 3 days. This means that influenza can spread faster than COVID-19.
For more information on the similarities and differences visit the Centers for Disease Control and Prevention (CDCP) website.
How much time should I leave between having the COVID-19 vaccine and flu vaccine?
You should check with your health authority on what they recommend.
Will the flu vaccine also protect against COVID-19?
Flu vaccines will not prevent COVID-19, but they will reduce the burden of flu illnesses, hospitalisations and deaths on the health care system and conserve scarce medical resources for the care of people with COVID-19. Flu vaccines have been shown to reduce the risk of flu illness, hospitalisation, and death.
You can see a summary of the benefits of flu vaccination and selected scientific studies: www.cdc.gov/flu/prevent/vaccine-benefits.htm
Can I get a flu vaccine and COVID-19 vaccine at the same time?
You should check with your health authority on what they recommend. Your healthcare provider can help you decide the best vaccination schedule for you and your family.