User:Mr. Ibrahem/Influenza vaccine

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.

The vaccines are generally safe. Fever occurs in five to tenpercent of children vaccinated. Temporary muscle pains or feelings of tiredness may occur as well. In certain years, the vaccine has been linked to an increase in Guillain–Barré syndrome among older people at a rate of about one case per million doses. Although most influenza vaccines are produced using eggs, they are still recommended for people who have severe egg allergies. However, influenza vaccines are not recommended in those who have had a severe allergy to previous versions of the vaccine itself. The vaccine comes in inactive and weakened viral forms. The live, weakened vaccine is generally not recommended in pregnant women, children less than two years old, adults older than 50, or people with a weakened immune system. Depending on the type they can be injected into a muscle, sprayed into the nose, or injected into the middle layer of the skin (intradermal). The intradermal vaccine was not available during the 2018–2019 and 2019–2020 influenza seasons.

Vaccination against influenza began in the 1930s with large-scale availability in the United States beginning in 1945. Every year the WHO chooses which strains are included in the vaccine. It is on the World Health Organization's List of Essential Medicines. The wholesale price in the developing world is about US$5.25 per dose. In the United States, the vaccine costs less than US$25 per dose,.