Who should be vaccinated annually

Anyone anywhere can catch influenza and the influenza vaccine can be administered to any person aged 6 months or older to reduce the chance of getting influenza, or to reduce the severity and consequences of the disease. Yet, national and international health authorities worldwide recommend that the influenza vaccine be given to protect people who […]

How effective they are

Vaccination is the most effective way to prevent influenza. Effectiveness of the vaccination varies with the age and immune status of the vaccinated person, the (sub)type of the virus, the degree of similarity between the vaccine and the circulating virus strains, and the length of time from vaccination to exposure to influenza virus. It is […]

Vaccines in cultured cells

An alternative way of producing influenza virus for vaccine production is based on the use of cell cultures in a biological fermentation process. Mammalian cells are usually used for this purpose. The cells are infected with the virus and the virus is left to multiply for several days. During the course of this process, most […]

Vaccines in chicken eggs

Influenza vaccine manufacturers use the primary seed virus strains to produce vaccines that match the strains of the respective virus subtypes that are likely to circulate during the next influenza season. First, the virus strains are separately propagated in embryonated chicken eggs to produce large amounts of the viruses, called the working seed virus stock. […]

Viruses for the vaccine

Each year, the seasonal influenza viruses change slightly which leads to a less perfect match between the vaccine viruses and the circulating viruses, rendering the vaccine used in previous years less effective. Therefore, each year, a new vaccine must be prepared that will be effective against the influenza virus strains that are expected to circulate […]


There are in principle two types of seasonal influenza vaccines. The first is the traditional flu shot, which is an inactivated vaccine that does not contain live virus. It is given by injection, usually in the upper arm muscle. Inactivated vaccines are available in three forms: whole-virus, split-virus, and subunit-virus vaccines. Whole-virus vaccines are classically […]

Difference between vaccines, antivirals and antibiotics

Influenza vaccines prevent or mitigate infections. They are designed to induce a protective immune response in the body against the viruses represented in the vaccine. When vaccinated, the immune system of the body produces a specific response, consisting of specific T cells and specific antibodies that fight off the infection when exposure to the virus […]


Timely collection and exchange of information on influenza activity is of utmost importance when it comes to reducing the burden of influenza worldwide. National and international networks for the clinical and virological surveillance of influenza have therefore been established everywhere. The WHO Global Influenza Surveillance Network comprises 4 WHO Collaborating Centres (London, Tokyo, Atlanta and […]