Influenza vaccine

Influenza vaccines, commonly known as flu shots or flu jabs, are designed to protect against infection by influenza viruses. Due to the rapid mutation and variation of these viruses, the composition of the vaccines is reviewed and updated biannually to match circulating influenza strains.

Influenza Vaccine (51551576704)

Universal Influenza Vaccine Clinical Trial (46628342315)

Composition and Development

The influenza vaccine is a mixture of inactivated (killed), or attenuated (weakened), influenza viruses. They are usually grown in chicken eggs, although newer vaccines may be grown in cell culture. The strains represented in the vaccine are selected twice a year based on surveillance data indicating which viruses are circulating and predictions about which strains are most likely to circulate in the coming season.

Efficacy

The effectiveness of the influenza vaccine varies from season to season, largely due to the degree of similarity between the viruses in the vaccine and those in circulation. When there is a good match, the vaccine significantly reduces the risk of influenza and its complications.

The United States Centers for Disease Control and Prevention (CDC) estimates that influenza vaccination reduces the risk of illness by 40% to 60% among the overall population when the vaccine viruses are like the ones spreading in the community.

Implications for Public Health

Influenza vaccination has broad public health implications. It reduces the burden of illness, medical visits, hospitalizations, and deaths associated with influenza. Vaccination also offers some indirect protection to unvaccinated community members by reducing the overall prevalence of the disease and thereby limiting its spread – a phenomenon known as herd immunity.

In the workplace, vaccinated individuals who contract influenza generally have milder symptoms and return to work faster compared to their unvaccinated peers. For older adults and individuals with chronic health conditions, vaccination is an essential preventive measure against severe illness.

Recommendations

Annual influenza vaccination is recommended for all individuals aged six months and older, particularly those at high risk of serious complications, such as young children, older adults, pregnant women, and people with chronic health conditions.

See Also

• Influenza
• Vaccine
• Herd immunity