COVID rebound can happen whether or not you take Paxlovid

What initially was known as “Paxlovid rebound”—a return of COVID signs or take a look at positivity after beginning a course of the antiviral—is now extra precisely known as “COVID rebound,” as a result of rebound can occur no matter whether or not somebody takes antivirals.

What’s extra, it is doubtless not a phenomenon distinctive to COVID, says virologist Andy Pekosz, Ph.D., a professor in molecular microbiology and immunology. What is exclusive to COVID is the know-how—particularly speedy antigen assessments—that permits us to trace the progress of an an infection so intently.

Researchers are persevering with to analyze why some folks expertise COVID rebound, whether or not individuals are contagious throughout this era, and the position antivirals like Paxlovid would possibly play. However one factor is definite, says Amesh Adalja, MD, a senior scholar on the Johns Hopkins Middle for Well being Safety who makes a speciality of infectious diseases and pandemic preparedness: The chance that somebody would possibly expertise delicate rebound signs shouldn’t deter them from taking Paxlovid if they’re at the next danger for severe illness.

What’s COVID rebound?

COVID rebound is “usually described as a recurrence of indicators or signs or a brand new constructive viral take a look at outcome after preliminary restoration from COVID-19,” according to the CDC. The order of occasions usually appears like this: An individual is contaminated with and has signs of COVID; their signs subside over the course of the an infection, and so they take a look at adverse for COVID on a house antigen take a look at; their signs return, and so they might take a look at constructive once more on a house antigen take a look at.

Rebound signs are usually delicate, and no hospitalizations or deaths have occurred because of rebound, according to a December 2023 CDC report.

Why do some folks expertise COVID rebound?

Researchers are nonetheless working to know why rebound occurs and the way it varies from individual to individual—with some experiencing a return of signs and others solely seeing proof via antigen testing. However at a molecular level, the truth that rebound happens is no surprise, says Andy Pekosz.

“We take into consideration an an infection as beginning as nothing, going as much as a peak, after which going away, however in actuality, your physique is far more sophisticated than that,” he says. Utilizing extra delicate instruments, virologists have seen that the quantity of virus current in somebody with COVID goes up and down over the course of an an infection, inflicting completely different levels of signs.

Does Paxlovid trigger rebound signs?

A CDC review of COVID rebound research discovered “no constant affiliation between remedy and rebound.” Paxlovid doesn’t instantly trigger signs to return; in reality, solely about 1 in 5 people who take Paxlovid expertise rebound, and lots of of these are asymptomatic.

“Paxlovid is taken day by day for 5 days, and it is doable that the immune response is considerably blunted throughout that interval. The speculation is that after these 5 days, the drug stress from Paxlovid is gone and no matter remnants of the virus are nonetheless current are capable of trigger signs once more,” Adalja says. “We do not fairly perceive why it occurs in some folks and never others, however it doubtless has to do with the nuance of the immune response and the way that is impacted by antivirals.”

The danger of rebound shouldn’t preclude somebody who’s at excessive danger or extreme illness from taking Paxlovid, and it positively should not preclude docs from prescribing it. “Taking Paxlovid clearly reduces the probability of a person creating extreme COVID, regardless of COVID rebound,” Pekosz emphasizes.

Can COVID rebound occur to individuals who do not take Paxlovid?

Sure. In fall 2020 and spring 2021—earlier than Paxlovid turned out there—Pekosz and different virologists studied how infectiousness and viral load diversified amongst people over the course of a COVID an infection. Their outcomes confirmed quite a few cases of what we now describe as COVID rebound: a return of signs or constructive antigen take a look at.

These outcomes weren’t surprising, based on Pekosz. “Many people virologists assumed [rebound] was occurring as a result of we perceive that these viruses come and go, they are not clean curves by way of your responses,” he says.

Is an individual contagious whereas they’ve rebound signs?

Probably—however Adalja explains that contagiousness is best decided by take a look at positivity than signs. “If an individual experiences rebound signs however does not take a look at constructive on a house antigen take a look at, they doubtless aren’t shedding sufficient virus to be infectious,” he says. “Nonetheless, in the event that they take a look at constructive on a house antigen take a look at, that does doubtless correlate with contagiousness.”

When somebody assessments constructive on a house antigen take a look at, does the darkness of the take a look at line correlate to contagiousness?

A faint line on a house antigen take a look at continues to be a constructive take a look at outcome. “The assessments are validated to inform you sure or no” as to whether it detects viral materials, Pekosz explains, not how contagious you’re. “A darkish line does imply extra viral load,” he says, however there isn’t any system that correlates completely different shades of crimson with degree of contagiousness.

“In the event you’re testing constructive following a earlier adverse take a look at or following a full course of Paxlovid, that is the place masking and distancing turns into essential,” Pekosz says. “However once more, solely on the tail finish of an an infection, if you’re feeling higher and signs aren’t extreme.”

Does rebound occur with different viruses, like flu and RSV?

It is doubtless that rebound happens with different viral infections, Pekosz explains. “It most likely occurs with influenza, however we do not have the at-home assessments to seize that,” Pekosz says, including that he hopes future availability of at-home flu assessments will enable virologists to research flu instances like they’ve with COVID.

“What we are able to do by way of diagnosing ourselves with COVID and following the course of the illness is light-years forward of what we are able to do for influenza,” Pekosz says. “It is a testomony to the truth that we have executed good science and gotten these instruments in place to see these sorts of variations that we have by no means been capable of see with different viruses or infections.”