Noeleen Lynch has had a sore back on and off throughout her life. When the pain resurfaced in early February, she didn't think much of it. She took some painkillers and went out to celebrate her husband's birthday, but the sensation, which felt like a persistent muscle spasm, kept getting worse.
Two days later, she tested positive for COVID-19.
Lynch, a 37-year-old charity director in Belfast, Northern Ireland, developed other symptoms as well, including fatigue and brain fog — but the back pain was by far the worst.
"It was awful," she told Insider, adding, "It really limited my mobility."
She struggled to get into and out of bed or walk down the stairs. She couldn't lift her young children, ages 2 and 4. A few days into her illness, she sat up from her chair after an important meeting, paralyzed with pain. Her husband had to guide her to the sofa.
Back pain wasn't a common COVID-19 symptom before the Omicron wave. Now it ranks among the variant's top 20 symptoms according to the Zoe COVID Symptom Study, which uses a smartphone app to log how hundreds of thousands of people are feeling every day across the UK. In a video on February 10, the study's principal investigator, Tim Spector, said around 20% of people with Omicron reported back pain. Spector also experienced back pain firsthand during his COVID-19 illness in February.
Insider spoke with two other people who attributed their recent back pain to Omicron. Both of them, like Lynch, had received three COVID-19 shots.
Alaina Bartel, a 29-year old writer and editor in Cleveland, Ohio, described excruciating back pain in January, around the same time as her COVID-19 diagnosis.
"I had a kidney stone two years ago and it was really similar to that," she said, adding, "I couldn't breathe, really, because it hurt so bad."
Bartel considered checking into the emergency room, she said, but the intense pain resolved after about 15 minutes. She continued to have dull pain for another few days, she said.
Katie Ferrari, a 33-year-old teacher in Oakland, California, also developed back pain roughly one day before testing positive for COVID-19 in December. She likened the sensation to period cramps or doing kettlebell swings with poor form, "but a little more intense."
Doctors aren't sure why back pain is more commonly reported with Omicron than with prior variants like Delta.
It may be a numbers game: Omicron causes more infections than other variants, so it's likely to produce a broader range of symptoms. Doctors and patients may also be paying closer attention to milder symptoms than they were at earlier points in the pandemic, when vaccines weren't available and COVID-19 cases tended to be more severe.
But Omicron could also attack the body in unique ways.
Dr. Peter Whang, an associate professor in the Yale Department of Orthopaedics and Rehabilitation, said back pain among COVID-19 patients is more akin to a muscle ache than a compressed nerve. It often appears out of the blue, he said, in tandem with other viral symptoms.
"Certainly there could be something inherent to Omicron that makes it more likely to affect the musculoskeletal system," he said, adding, "But we just don't have that understanding at this point."
Some COVID-19 patients with back pain may be experiencing a flare-up of an existing problem, like arthritis or generalized back pain from sitting too long at the computer. Viral infections produce inflammation, which can exacerbate underlying health problems and generate new symptoms.
"If you're on a tight deadline and you're at your seat typing away for eight hours, you're going to have back pain," Whang said. "I think all of us can agree that, for the most part, our activity level may not have been the same as it was before the pandemic — and obviously Omicron came on later on in the pandemic."
All three people who reported back pain to Insider said the symptom has either improved or completely resolved since their illness started. Bartel said she took pain medication for a few days, but is feeling "100% better" now. Ferrari doesn't have any lingering physical symptoms, either — though she said her depression has gotten worse after having COVID-19.
Lynch said her back pain still persists after several weeks, but she's a lot more mobile now. She credits her improvement to seeing a physical therapist, who is helping stretch out her muscles.
"It was pretty debilitating when it lasted," she said of the spasm-like pain. "Thankfully, it's gone."