DES MOINES, Iowa — The virus struck. Cyndee Davis, a retired health care worker, took a prescription. Symptoms improved. The prescription ended. Symptoms got worse.

That’s been the struggle for Davis. “I’d say every bit as nasty as it first hit,” Davis said Tuesday from her home in Des Moines.

Davis said that she first tested positive for COVID-19 two weeks ago. Her doctor prescribed Lagevrio. (She couldn’t take the more commonly prescribed drug, Paxlovid, because she already takes a blood thinner for a pre-existing health condition, she said).

But patients can only take the prescription for about five days. Davis said that a few days after her prescription ended, her symptoms worsened again. “It came back on me with the same amount of fierceness as the first time through,” she said, “…kind of sucks.”

Fever, pounding headache, body aches. “Rebound COVID.”

That’s the term doctors are using for what’s happening to Davis. A person gets infected with COVID-19 (especially the new BA.5 subvariant that’s spreading across the country), starts a prescription, symptoms lessen, the prescription ends, symptoms worsen. Rebound COVID.

“I don’t know that any of them (prescriptions) are perfect enough to say it’s going to shrink it down to a five-day course,” said Dr. AJ Stefani, a hospitalist at UnityPoint Health Des Moines.

Stefani doesn’t believe the virus disappears and then reappears after the patient’s prescription ends. He thinks the virus is still active but the medicine was working to reduce the symptoms.

But Stefani believes that the prescriptions make a difference and can lessen the impact of the virus, even if patients can only take them for several days. And his experience with rebound COVID is that it is fairly rare.

Anecdotally, he says that about one in ten virus patients who took a prescription experienced rebound COVID. “So I do think it’s worth it (taking the prescription), especially for those that are high risk of potentially more devastation side effects.”