CDC: No clear relationship between antivirals and COVID ‘rebound’ infection

There is no consistent association between COVID-19 antiviral treatments and “rebound” infections, according to a new analysis from the Centers for Disease Control and Prevention (CDC). 

Early treatment with an antiviral such as Paxlovid or remdesivir prevents hospitalization and death among patients with mild to moderate COVID-19 who are at risk for severe disease. But although antiviral therapies are widely available, they are underutilized — possibly because of concerns over rebound.

A CDC review of existing studies found COVID-19 rebound can happen in patients whether they received antiviral treatments or not.

There are lingering questions about whether the timing of when a person starts taking an antiviral or whether there are underlying conditions that make a person more susceptible to severe disease also increase the risk of rebound.

“Risk factors for rebound appear to be similar to risk for severe disease, but further studies are needed to understand whether persons with certain characteristics or underlying medical conditions are predisposed to experiencing rebound,” the CDC said.  

Still, no hospitalizations or deaths due to a rebound were reported.

Rebound symptoms typically appeared as a mild illness three to seven days after the initial illness ended, and officials and infectious disease experts agree the substantial benefits of treatment outweigh the risk of COVID-19 rebound.

Rebound does not likely represent reinfection or resistance to treatment, but the CDC said more studies are needed to confirm that.

“The most important message you need to get across is that rebound does not carry the same risk,” said Michael Mina, an epidemiologist and chief science officer at digital health company eMed. “So if your goal in taking a medicine is to not land yourself in the hospital when you get COVID, take the medicine.” 

CDC encourages vaccines in nursing homes

Separately, the CDC reiterated the need for nursing home residents to be vaccinated against COVID-19, flu and RSV.  

This year is the first time vaccines are available to protect older adults against all three fall/winter respiratory illnesses, but the agency said vaccination rates in nursing homes are extremely low.

As of Dec. 10, only 33 percent of nursing home residents were up-to-date with vaccination against COVID-19. Among residents at nursing homes that elected to report, 72 percent had received a flu shot, but only 10 percent had received an RSV vaccination. 

The actual RSV number is likely higher, however, because facilities aren’t required to report RSV vaccinations.

Among the general population, RSV vaccination coverage among adults 60 and older was just 17 percent.  

Vaccine fatigue, inaccurate health information and vaccine hesitancy contribute to lack of vaccine demand, the CDC said.

Lower coverage in certain areas might be related to challenges to vaccine access and cost and payment barriers associated with COVID-19 vaccine commercialization, the agency said.  

The low RSV vaccination coverage relative to the other two vaccines might be driven by the relative recency of the recommendation, vaccine fatigue associated with the introduction of a fourth respiratory vaccine (in addition to flu, COVID-19 and pneumonia), and the recommendation being based on shared clinical decision-making between a patient and a health care provider, rather than a full endorsement.