Covid-19 is putting Cumbria's ambulance crews under "extreme pressure" with about an extra 40 callouts a day, the emergency service has warned.
One patient recently had to wait five hours to be handed over to a hospital.
Roger Jones, from the North West Ambulance Service, said the new strain of the virus affecting younger people is causing a problem.
"This is the hardest time that I have ever known in the NHS," said Mr Jones, a veteran of 35 years.
"As you can imagine, the system that we work in is smaller than in London and the geographical area is greater so those extra 40 calls do put extreme pressure on our resources that we currently have.
"We have unfortunately seen some extended handover times on occasions, these have usually been at times of extreme pressure".
It comes as public leaders across the county urged people to "stay safe and stay local" during lockdown, as several hospitals suspended outpatient appointments to cope with a rise in cases.
Police said 68 fines were issued to people travelling to the Lake District last weekend.
In Cumbria, the ambulance service is experiencing 20 to 24% above average calls, with the wider north west region seeing an extra 1,000 calls a day.
"The new strain is affecting the younger population with more symptoms now, it's making them more ill than they might have done with the original strain and that is what's causing the pressures at this time," Mr Jones told BBC Radio Cumbria.
Most clinically-vulnerable staff have been vaccinated, Mr Jones said, with others receiving the vaccine "on an ad-hoc basis" as it has been made available.
"I have never been so proud to work for the ambulance service at this time," he added.
"They are very tired, they have been working with the Covid-19 virus for nearly 12 months and I must say that they have absolutely risen to the cause."
Meanwhile Cumbria County Council has heard that not all people eligible to receive a vaccine have taken up the invite, the Local Democracy Reporting Service said.
When asked why not, Pam Duke, assistant director for provider services, told a meeting that while 85 to 90 per cent had done, it was "a personal choice".
"Let's remember they are not being forced to take the vaccination," she added.