A traditional winter enemy: the flu

It has turned into a habit to write about flu every year. It is only natural considering influenza (flu) is a contagious respiratory illness that comes back every winter, caused by the influenza virus that can regularly change, mutate and cause mild to severe illness.

Older people, young children and people with ongoing health conditions are at high risk of serious flu complications, which can result in hospitalisation and death.

Each year research indicates the influenza viruses that will be most common during the season and the vaccine for the year’s flu season is designed and produced according to that.

Symptoms of flu are well known, like cough, sore throat, runny or stuffy nose, muscle or body aches, headaches and fatigue, but it is important to note that not everyone with flu will have a fever. Vomiting and diarrhoea occur more frequently in children.

Flu is highly contagious

Flu viruses spread mainly by droplets, expelled when people with flu cough, sneeze or talk. These droplets can land in the mouths or noses of people who are nearby or on a surface or object that might be touched by anyone who then touches their own mouth, eyes or nose.

Adults may be able to infect others from one day before symptoms develop and up to five to seven days after becoming sick. Children may pass on the virus for longer than seven days. Symptoms start one to four days after the virus enters the body. 

That means that it is possible 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. Those people may still spread the virus to others.

Is the flu dangerous?

Flu is unpredictable and can be severe, resulting in thousands of deaths.

Each season the severity of flu depends on which flu viruses are spreading, how many people get vaccinated and how well the flu vaccine is matched to the year’s flu viruses.

But it also depends on the infected person as certain people are at greater risk of serious complications if they get the flu. This includes older people, young children, pregnant women and people with health conditions such as asthma, diabetes or heart disease.

Who should get vaccinated and when?

Everyone from six months of age should get a flu vaccine every season.

There are only a few exclusions that should be assessed by the health team administering the vaccine.

Ideally, yearly flu vaccination should begin as soon as the vaccine is available, usually at the beginning of October.

In the Northern Hemisphere, winter is the time for flu, but the exact timing and duration of flu seasons vary. While seasonal flu outbreaks can happen as early as October, most of the time flu activity peaks between December and February, although activity can last until as late as May.

However, getting vaccinated, even if it is later, can give protection as long as flu viruses are circulating. It takes about two weeks after vaccination for antibodies to develop in the body in order to protect against influenza virus infection.
There is still time for those who have not been vaccinated to do it so they are protected before influenza gets to its peak of nasty activity, spreading like wildfire throughout their community. The ones who have not been vaccinated are the ones in danger.

Vaccination to prevent influenza is particularly important for people who are at high risk of serious complications from influenza, but health authorities in several countries have voted that flu vaccination should be universal to expand protection against the flu to include more people.

Why is a flu vaccine needed every year?

A flu vaccine is needed every season for two reasons. First, the body’s immune response from the vaccination declines over time, so an annual vaccine is needed for optimal protection. Second, because flu viruses are constantly changing, the formulation of the flu vaccine is reviewed each year and sometimes updated to keep up with changing flu viruses.

There is still a possibility to get the flu, even having had the vaccine, as the protection acquired depends on various factors, including the age and health status of the person and also the similarity between the viruses used to make the vaccine and those circulating in the community. If the viruses in the vaccine and the ones circulating are closely matched, vaccine effectiveness is higher. But even when the viruses are not closely matched, the vaccine can still protect many people and prevent flu-related complications. This is possible because antibodies made in response to the vaccine can provide some protection (called cross-protection) against different but related influenza viruses.

A flu vaccine cannot give you flu illness. The viruses in the flu shot are killed (inactivated), so you cannot get the flu from a flu shot.

We have to get to the conclusion that to avoid getting the flu and its possible consequences the only factor that exclusively depends on our own decision is to get the vaccine.

The single best way to prevent the unpredictable health dangers of seasonal flu is to get a flu vaccine each season.

If you have not done it, there is still time to protect yourself and by doing it you will also protect the ones around you.

Forgive me if I am repeating the same thing every year, but I hate seeing people get ill with a disease that they could have actively done something to avoid.

Best health wishes,
Maria Alice

By Dr Maria Alice
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Dr Maria Alice is a consultant in General and Family Medicine. General Manager/Medical Director – Luzdoc International Medical Service / Medilagos. Medical Director – Grupo Hospital Particular do Algarve