How effective is the flu vaccine in preventing the disease?

Science and Health

Many people mistakenly believe that the flu is just a mild cold or a winter ailment. However, the Health Ministry emphasizes that influenza is a highly contagious and severe viral disease.

The flu virus spreads through coughing, sneezing, and contact with nasal secretions and phlegm, which contain a multitude of viruses.

The infection rate for flu is alarmingly high. It primarily affects the respiratory tract and results in symptoms such as fever (over 38 degrees Celsius), sore throat, headache, runny nose, cough, muscle pain, weakness, fatigue, and loss of appetite.

Pneumonia is a common complication of the flu, often requiring hospitalization for vulnerable groups such as young children, pregnant women, the elderly, and immunocompromised individuals. 

To combat this, the Health Ministry recommends flu vaccination for everyone over the age of 6 months. The flu vaccines provide effective protection for one winter season.

Each year, a new vaccine formulation is produced containing the four strains of influenza expected to be prevalent in the upcoming year.

The UK’s flu program (or is it a programme?)

To understand the effectiveness of the flu vaccine, let’s examine the situation in the UK. The UK is at the forefront of childhood flu vaccination in the Western world and has implemented a systematic program to vaccinate children in schools for several years.

Yes, even if you are already sick. (man with a cold) (credit: SHUTTERSTOCK)

The vaccination takes place before winter using a nasal spray. Numerous studies conducted in the UK have not only shown a high response rate to the vaccine, but also significant effectiveness in reducing the spread of the virus and the risk of hospitalization.

According to the latest report published in July, which assesses the vaccine’s effectiveness annually, there was a two-thirds decrease in the risk of hospitalization among children aged 2-17 who were vaccinated against the flu. Most of these children received the nasal spray vaccine.

This year’s report, unlike previous seasons, primarily focuses on the dangers of the flu and its potential complications. It examines the vaccine’s effectiveness in preventing hospitalizations in children, whereas previous reports analyzed various parameters such as clinic visits or flu-like symptoms.

The UK recognizes that school students are particularly susceptible to the flu and act as major spreaders of the disease in the community. Consequently, the flu vaccination program in schools has been expanded throughout the UK for children aged 4-17.

It’s important to note that influenza is a complex disease that undergoes changes each season, presenting three to four different strains every winter. Therefore, revaccination is crucial, even if you or your child have already been exposed to the flu.

Exposure to one strain does not guarantee protection against other strains. Only through vaccination can the body generate natural antibodies against the specific flu strains identified by the World Health Organization as the cause of the disease.

Man with flu working in the office (credit: INGIMAGE)

However, it’s worth mentioning that vaccine effectiveness typically ranges between 50-75%. In some years, when the estimated vaccine strains do not match the actual flu strains, the effectiveness may fall below 50%. A study conducted during the 2020-2021 flu season in Denmark found high effectiveness (ranging from 66% among children aged 2-6 to 72% among children and adolescents aged 2-17) of the nasal spray vaccine.