Adults in the age group have been eligible for a top-up dose of the Covid-19 vaccine since mid-September, when the NHS launched its national booster jab campaign.
And UK scientists are set to announce an expansion of the booster programme, as the first cases of the newly discovered Omicron variant have been confirmed across England and Scotland.
NHS England data, published for the first time, shows 17,264 people aged 50 and over in Burnley had received a booster jab or third vaccine dose by November 21st.
That's at least 48% of the age group, based on the number of people on the National Immunisation Management Service.
Booster jabs are available for people in eligible groups who had their second dose at least six months ago, while third primary doses are offered to people with severely weakened immune systems.
Across the North West as a whole, around 53% of over-50s had received a booster jab or third dose by November 21.
Data shows falling levels of protection from symptomatic disease and hospital admission six months after people have had their second jab – particularly among older adults and at-risk groups.
Professor Anthony Harnden, deputy chairman of the Joint Committee on Vaccination and Immunisation, said experts have been looking at extending boosters to the under-40s and whether the time interval between the second and third doses of the vaccine should be cut in response to the arrival of the Omicron variant.
Prof Harnden said: "I think it’s almost inevitable that we’re going to see many, many more cases than we’ve seen before.
"The key question is whether this virus has a transmission advantage over the Delta, which is the prevalent virus at the moment."
The figures show that by November 21st in Burnley:
1,183 people aged between 50 and 54 had received a booster jab or third vaccine dose – 18% of the age group
1,596 people aged between 55 and 59 had an extra dose – 24%
As had 1,972 people aged between 60 and 64 – 34%
2,905 people aged between 65 and 69 – 60%
3,731 people aged between 70 and 74 – 78%
2,752 people aged between 75 and 79 – 81%
And 3,125 people aged 80 and over – 79%
Booster doses have so far been extended to all over-40s, following a recommendation by the JCVI prior to the discovery of the Omicrom virus in the UK.
Other groups currently able to receive a booster include frontline health and social care workers, along with adults aged 16 and over with underlying health conditions that put them at higher risk of severe coronavirus.