More than one million older people in England will be invited to get vaccines for respiratory syncytial virus (RSV), with health officials warning it is “not just a winter illness”.

While RSV infections are common and not usually serious, adults over the age of 75, babies under six months and people with a weakened immune system can become severely ill.

The virus can lead to serious complications like pneumonia and bronchiolitis, an infection that causes swelling of the small airways in the lungs.

In the coming days, about 1.3 million older people will be contacted to come forward for their vaccine, NHS England said.

Those aged between 75 and 79, or people who turned 80 after September 1, will be urged to book an appointment with their GP.

Steve Russell, national director for vaccinations and screening at NHS England, said: “RSV is not just a winter illness.

“We see cases increase in winter but it can occur all year round and can make older people seriously ill, so it is vital everyone eligible gets vaccinated – which is why are now working hard to reach anyone who hasn’t yet been jabbed and urging them to book an appointment.”

The vaccine for RSV was first rolled out in September 2024, with almost 1.5 million people getting jabs, including more than 1.3 million people aged between 75 and 80.

Pregnant women are also eligible for the jab from 28 weeks onwards.

According to NHS England, almost 150,000 pregnant women have had the jab since September.

Dr Conall Watson, consultant epidemiologist, UK Health Security Agency, said: “RSV can be severe in older people, causing serious lung infections like pneumonia and flare-ups of existing conditions.

“If you’re eligible, there is good evidence it will help give you protection – speak with your GP practice about getting the jab.”