Every vaccination programme has its pros and cons.

Pros:

  • 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.

Cons:

  • 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 6-12 months.