Influenza vaccines, also known as flu shots or flu jabs, are vaccines that protect against infection by influenza viruses.New versions of the vaccines are developed twice a year, as the influenza virus rapidly changes. While their effectiveness varies from year to year, most provide modest to high protection against influenza. The United States Centers for Disease Control and Prevention (CDC) estimates that vaccination against influenza reduces sickness, medical visits, hospitalizations, and deaths. Immunized workers who do catch the flu return to work half a day sooner on average. Vaccine effectiveness in those over 65 years old remains uncertain due to a lack of high-quality research. Vaccinating children may protect those around them.
The World Health Organization (WHO) and the US Centers for Disease Control and Prevention (CDC) recommend yearly vaccination for nearly all people over the age of six months, especially those at high risk. The European Centre for Disease Prevention and Control (ECDC) also recommends yearly vaccination of high-risk groups. These groups include pregnant women, the elderly, children between six months and five years of age, those with certain health problems, and those who work in healthcare.