Geneva: The World Health Organization has released its latest recommendations for the composition of influenza vaccines intended for the Southern Hemisphere’s 2027 influenza season, as health authorities prepare for the next major flu season.

The recommendations are based on continuous global surveillance of influenza viruses and are designed to help vaccine manufacturers select virus strains that are expected to provide the best available protection against viruses likely to circulate during the upcoming season.

Global influenza surveillance

Influenza viruses are constantly changing, which means vaccine formulations need to be reviewed regularly.

WHO works with a global network of laboratories and collaborating centres that collect and analyse influenza samples from different countries.

Scientists examine circulating viruses, their genetic characteristics and their antigenic properties to determine how closely they match currently available vaccines.

Why vaccine composition changes

Influenza vaccines are updated when surveillance indicates that circulating viruses have changed sufficiently to reduce the protection provided by an earlier formulation.

The process is particularly important because influenza can spread rapidly and cause substantial illness during seasonal outbreaks.

The recommendations provide manufacturers with information needed to begin producing vaccines well ahead of the relevant season.

Focus on Southern Hemisphere

The latest recommendation specifically concerns countries in the Southern Hemisphere.

Seasonal influenza patterns differ between the Northern and Southern Hemispheres, so vaccine composition is reviewed separately for each upcoming influenza season.

Countries can use WHO’s recommendations when making national decisions about influenza vaccination programmes.

Protecting vulnerable groups

Influenza can cause more severe disease in certain groups, including older adults, young children, pregnant women and people with some underlying health conditions.

Vaccination is an important public-health tool for reducing the risk of influenza illness and its complications.

Health authorities may give particular attention to groups considered at higher risk when developing seasonal vaccination campaigns.

Vaccination is part of a wider response

Vaccination is not the only measure used to reduce influenza transmission.

Respiratory hygiene, staying home when unwell, appropriate healthcare and surveillance of circulating viruses also contribute to seasonal influenza control.

Healthcare systems also prepare for periods when influenza activity increases and demand for medical services rises.

Importance of continuous monitoring

The composition of influenza vaccines is reviewed regularly because viruses can evolve and change their characteristics.

Global surveillance allows health authorities to identify important changes and provide updated recommendations.

This monitoring also helps scientists identify emerging influenza viruses that could require additional public-health attention.

Preparing for the 2027 season

The latest WHO recommendations provide the starting point for vaccine production and national planning for the Southern Hemisphere’s 2027 influenza season.

Manufacturers will use the recommended virus strains in developing the relevant vaccines, while individual countries will determine their own vaccination policies and programmes.

The process demonstrates the importance of international cooperation in tracking influenza viruses and preparing for seasonal outbreaks.