People aged 65 and over in England can now book their COVID-19 booster jab online or via 111.
The NHS is also offering appointments to carers and pregnant women as the vaccine rollout continues ahead of the winter months.
People aged 75 and over, the severely immunosuppressed and frontline health and care workers have been able to book a booster since last week.
Around 26 million people in England will be eligible for an autumn booster in the comings weeks.
Bookings can be done online or over the phone as long as the person had their last COVID-19 jab at least three months ago.
Dozens of hospital hubs are joining the rollout to administer the jab – plus flu vaccines where possible – to members of the public as well as NHS staff.
Eventually, all those aged 50 will be offered a vaccine.
Two vaccines have been approved that can be used as boosters this autumn and winter – one from Moderna and the second from Pfizer.
Both have been approved by the Medicines and Healthcare products Regulatory Agency (MHRA) to target both the original and Omicron strains of the virus.
COVID deaths in England and Wales fall for fourth week in a row
UK approves ‘next-generation’ COVID vaccine
Figures have shown that generally the Omicron variant is much less likely to leave someone in hospital than previous strains of the virus.
High levels of antibodies, from both natural infection and vaccines, are thought to be behind the fall in the number of deaths.
Click to subscribe to the Sky News Daily wherever you get your podcasts
NHS director of vaccinations and screening Steve Russell said: “There is no room for complacency in keeping COVID-19 on the back foot, and this autumn booster will help protect those most at risk.”
People who qualify for an autumn/winter booster include adults aged 50 and over, those aged five to 49 with health conditions that put them at greater risk, pregnant women, care home workers and frontline health and social care workers, carers and the household contacts of people with weakened immune systems.
COVID rates have been relatively low in recent months, with the UK COVID Alert level downgraded from three to two last week.
A level two alert means that “COVID-19 is in general circulation, but direct healthcare pressures and transmission are declining or stable”.