Speaking to the Post, city councillor Pav Akhtar has described how he was admitted to Royal Preston Hospital within hours of the jab.
The 42-year-old councillor for Plungington, who works full-time for the NHS, spent 24 hours in emergency care last week.
Coun Akhtar was among a number of NHS staff to receive the Pfizer/BioNtech jab last Friday (January 8) at a vaccination centre run by Lancashire and South Cumbria NHS Trust in Bamber Bridge.
But minutes later, as he was sat in the post-vaccine waiting area where patients are monitored for adverse reactions, Coun Akhtar began feeling unwell.
"Within 10 minutes, I could tell that my breathing pattern had changed. I was having to dig deeper into my diaphragm to breathe," said Coun Akhtar.
"My breathing went and I started to feel a bit nervous and clammy. I wasn't sure what was going on. But I tried to ignore it and told myself it would pass."
Feeling uneasy, Coun Akhtar returned home expecting the unpleasant side-effects to soon pass. But his condition rapidly deteriorated.
A short time later, he found himself led in a hospital bed in an isolation unit at Royal Preston Hospital where staff suspected he might have Covid-19.
"I didn't have an underlying health condition that was expected to trigger a reaction," said Coun Akhtar.
"But the flu-like snuffles and muscle ache kicked in, followed by a horrendous fever. When I closed my eyes to lay down I felt like the top of my scalp was melting and sliding down my face. It was horrible.
"I was really struggling with my breathing, I was so short of breath. So we called the ambulance and I was taken straight to A&E.
"My fever remained and the temperature shot up to 40°c. It was this combination of symptoms that made the A&E team suspect that I might have Covid-19 or a reaction to the vaccine.
"That was the scariest bit, when they said that they suspected I might have Covid and put me into isolation."
After 24 hours under close observation and after testing negative for the virus, Coun Akhtar's fever began to break and he was discharged home to continue his recovery.
He said: "Thankfully, I'm all rested and recovered now, but there were a few ropy moments where I got a bit nervous and I wasn't sure what was going on.
"It was about five days later when I started to feel myself improving. I was still aching, but I forced myself to get up and out of bed."
Despite his scare, Coun Akhtar remains positive about the benefits of vaccines and the important role they will play in overcoming the pandemic.
He said he will still have his booster jab in March to ensure he benefits from the 95% protection the full dose of the vaccine is said to offer.
"It's been a week now and I feel perfectly fine," he said, adding,"I also feel mentally stronger because I know I'm on my way to protecting myself from Covid-19.
"I’m still firmly in favour of getting vaccinated. It’s the only realistic way to help us rediscover some semblance of normality.
"But I felt that it was important to acknowledge side effects can happen to some of us. But we will also get through these setbacks and we should not be afraid of the vaccine.
"I’m glad I got a jab because, at this point, our choice is between getting Covid or getting vaccinated. And we all know which is worse.
"I’m all sorted now and some older and much frailer family members have had their jabs without any side effects.
"Everyone definitely needs to get their vaccination as soon as it's offered to them, so that we can start to get some control on the disease.
"We all need to play our part. We need to help my NHS co-workers, and social care staff, other essential workers, and our communities by getting the vaccine.
"The vaccine is our best hope at this time, as it will massively cut the risk of catching Covid-19 and the relatively small possibility of some side effects shouldn't put us off getting vaccinated.
"This is our shot to get back to some semblance of normality. Getting vaccinated will help protect us and our loved ones."
You can find the latest coronavirus case figures for Lancashire here.
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