COVID symptoms can rebound in up to one-third of untreated people
New research suggests that around one-third of people suffering from COVID-19 could experience a rebound in symptoms several days after initially recovering. The research, looking at untreated COVID patients, follows growing reports of disease recurrence after antiviral treatment with Paxlovid.
Relatively soon after the COVID-specific antiviral drug Paxlovid was approved in late 2021, anecdotal reports started to reveal significant numbers of patients were seeing disease symptoms return days after completing the five-day treatment. Earlier this year, researchers at the University of California San Diego School of Medicine published a study indicating insufficient exposure to the drug was the most likely cause of these "Paxlovid rebounds."
But underpinning that conclusion was the question of whether these kinds of COVID symptom rebounds occur in the normal course of the disease.
“COVID rebound is a real phenomenon," explained Davey Smith, lead researcher on both COVID rebound studies. "It is complex, involving multiple factors, and its biological underpinnings remain unclear. More research is required. In this latest study, however, we wanted to see if symptom rebound also occurred during the natural history of COVID-19.”
To explore this phenomenon in untreated COVID patients, the researchers reviewed data from a clinical trial conducted in 2020 testing a potential new drug. The researchers looked at data from 158 trial participants who were in the placebo group and had documented symptoms of a COVID infection.
Of that cohort, 48 participants (30%) reported at least one defined symptom of COVID returning after two consecutive days being symptom-free. The most common symptoms to recur were cough, headache or fatigue, and 85% of those with recurrent symptoms reported them as mild.
Another study from the same research team, still unpublished and in pre-print, looked at the dataset but also tracked viral load in those participants experiencing COVID rebound symptoms. That research found only a small minority of those experiencing recurrent symptoms showed high levels of infectious virus.
"In an analysis of participants with both high-level SARS-CoV-2 RNA rebound (≥5.0 log10 copies/mL) and symptom rebound, only 1-2% had evidence of symptom rebound after initial symptom improvement," the preprint study stated. "Together, these results show that while waxing and waning symptom course may be commonly reported, symptom relapse with high-level viral load rebound is rare."
Speaking to NBC news, Smith said he was surprised to find one-third of participants reported a rebound in symptoms. And it implies the natural course of the disease may wax and wane over the course of several weeks, regardless of whether one has taken Paxlovid.
“Symptoms fluctuate, and viral antigen in the nose fluctuates, and they fluctuate with and without Paxlovid," Smith said.
The new study was published in JAMA Network Open.
Source: UC San Diego