Publication date 10/09/2015 - 00:00 Modification date 11/02/2018 - 18:32
- Provided the influenza strains in the vaccine are similar to those in circulation, vaccination protects risk groups against the complications arising from influenza (e.g. pneumonia, the exacerbation of underlying illnesses such as lung or heart disease, diabetic emergencies), hospitalization, and death.
- Vaccination reduces the likelihood of contracting
(serologically confirmed) influenza by 50-90% (average 67%);
amongst the elderly these figures are 30-70%. It also reduces
influenza-related complications in the elderly by 20-50%. If a
vaccinated patient nonetheless contracts influenza, the illness
usually runs a milder course. On average, influenza vaccination
prevents an estimated 12% to almost half of mortalities and a
quarter to a half of hospitalizations following influenza and its
complications. The effectiveness of vaccination depends (amongst
other factors) on the match between the influenza strains in the
vaccine and those in circulation, and of the virulence and
epidemiological activity of the circulating influenza viruses.
- Influenza vaccination causes local side effects in 20-59% of those vaccinated, although these effects are almost always mild and short-lived (a day's painful, red swelling at the site of the injection). Serious side effects are seldom reported.
- The influenza vaccination has to be repeated every year. This
is because the virus strains in actual circulation change every
year and the vaccine has to be adapted accordingly. But also
because the vaccine is held to offer protection for no more than