The town had previously led the way, with one of the highest uptakes in the country.
But in the past few weeks fewer and fewer residents have gone to vaccination centres across the borough to get jabbed, leading the town’s director of public health, Julia Burrows, to urge people to get protected.
So far this month 1,282 residents aged 16 and over have had their first jab, compared to more than 3,700 people in the entirety of August - and on one day just six people across the whole borough had their first dose.
With the second dose, 4,806 people in the town have been jabbed so far in September but this is a vast decrease on last month’s figure of 8,955 - on one day just 18 people had their second dose.
A total of 176,897 people have had at least one dose of the coronavirus vaccine, an 84.1 per cent uptake, and more than 164,140 have had two doses, a 78 per cent uptake.
Ms Burrows said: “Overall Covid-19 infection rates in Barnsley have levelled off.
“This is very welcome, as we feared there would be a quick and steep climb to very high rates.
“However, although there is some reprieve, rates are climbing quickly in school-aged children since schools reopened
“It is very reasonable to expect this to lead to a further spread across ages, and so a return to rising rates should be expected.
“Covid-19 vaccination is a powerful source of protection for everyone who is eligible.
“It is also a way to control overall spread.
“Unfortunately, after a very strong early start in the vaccination programme locally, we have seen slowing in uptake of the vaccine, especially in people aged under 40 years.
“We are now behind the national average, having previously led the way.
“Please get your vaccine, to help protect yourself and others.”
The NHS in Barnsley started to deliver Covid booster jabs to people in eligible groups this week.
Those who are eligible for their third jab are people living in residential care homes for older adults, everyone aged 50 and over, frontline health and social care workers, people aged 16 to 49 who have underlying health conditions, and adult household contacts of immunosuppressed individuals.
“They will receive their booster from six months after their second dose, allowing those who are most vulnerable to be prioritised and given their boosters quicker,” Ms Burrows added.
“The NHS will be in touch when you become eligible for the jab and there will be instructions on who to contact to book your booster vaccine.
“Please do not contact your GP surgery.”
There are two drop-in clinics this weekend at Priory Campus in Lundwood for residents aged 16 and over who want either their first or second dose of the vaccine.
On Saturday the clinic will be open from 9am to 5pm, and on Sunday from 9am to 4pm.