COVID symptoms rebound after Paxlovid may be due to immune system response

A rebound of COVID-19 signs in some sufferers after taking Pfizer’s antiviral Paxlovid could also be associated to a sturdy immune response reasonably than a weak one, U.S. authorities researchers reported on Thursday.

They concluded that taking an extended course of the drug – past the beneficial 5 days – was not required to cut back the chance of a recurrence of signs as some have recommended, based mostly on an intensive investigation of rebound in eight sufferers on the Nationwide Institutes of Well being’s Scientific Middle.

All sufferers within the research had developed sturdy immune responses, however researchers discovered greater ranges of antibodies within the sufferers who skilled a rebound.

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The crew stated their knowledge argues towards the speculation that impaired immune responses are the explanation signs return in some sufferers.

“Our findings counsel {that a} extra sturdy immune response reasonably than uncontrolled viral replication characterizes these medical rebounds,” the crew wrote.

The research, printed within the journal Scientific Infectious Illnesses, adopted quite a few reviews of people who took Paxlovid as beneficial inside 5 days of an infection and noticed a return of signs after they accomplished the five-day course of remedy.

President Joe Biden and Nationwide Institute of Allergy and Infectious Illnesses Director Dr. Anthony Fauci each skilled a COVID rebound after taking the drugs.

The instances raised considerations that Pfizer’s two-drug antiviral remedy may intervene with improvement of a long-lasting immune response.

The research concerned six individuals whose COVID signs returned after taking Paxlovid, and two with rebound signs after obvious restoration who didn’t take the tablets. Their responses had been in comparison with a bunch of six individuals who had COVID however didn’t expertise a rebound. All volunteers had been vaccinated and boosted and all had been contaminated with some model of the Omicron variant of the virus.

Blood from research volunteers underwent intensive investigation to evaluate their immune response throughout the acute an infection section and the rebound section.

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All the rebound sufferers had skilled important enchancment of their signs earlier than their rebound. Of those that had a rebound after Paxlovid, 4 had milder signs than throughout their preliminary an infection, one had the identical stage of severity and one reported worse signs.

Not one of the rebound sufferers required further remedy or hospitalization.

Rebound signs could also be partially pushed by a sturdy immune response to residual virus within the respiratory tract, the research authors recommended. They concluded that the drug doesn’t impede the immune response in some people, as some had feared.

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Bigger and extra detailed research are wanted to additional perceive COVID symptom rebound, the analysis crew stated, including that the present knowledge helps the necessity for isolation of such sufferers.

The researchers additionally recommended that there’s nonetheless a necessity to guage longer programs of Paxlovid in immunocompromised people the place the immune response could also be ineffective.