Detailed analysis of eight patients published.

Colorized scanning electron micrograph of a cell infected with the Omicron strain of SARS-CoV-2 virus particles (purple), isolated from a patient sample. NIAID

Participants were selected from adults enrolled in an ongoing COVID-19 study at the NIH Clinical Center in Bethesda, Maryland, and other local hospitals. The study aims to better understand how SARS-CoV-2 affects white blood cells. Participants provide blood and other samples as well as access to their COVID-19 medical records as part of the study. The study to evaluate COVID-19 rebound included six participants (three men and three women with a median age of 42 years) who took Paxlovid within four days of initial symptom onset and then experienced recurrent symptoms; two participants (a 54-year-old man and 35-year-old woman) who experienced recurrent symptoms who did not take Paxlovid; and a control group of six people who had COVID-19 but did not experience symptom rebound. All participants were previously vaccinated and boosted against COVID-19, and none developed severe disease requiring hospitalization during acute infection or rebound. Investigators collected data on each participant’s clinical course and performed laboratory tests on blood and nasal swab samples.

Investigators found no evidence of genetic mutations that would suggest participants who experienced COVID-19 rebound were infected with a strain of SARS-CoV-2 that was resistant to Paxlovid. They also found no evidence of delayed development of antibodies in participants experiencing rebound after taking Paxlovid. Investigators detected robust SARS-CoV-2 T-cell responses in rebound patients. Overall, the level of T-cell responses was greater in rebound patients than in patients with early acute COVID-19 who did not experience rebound. Infectious SARS-CoV-2 was detected by viral culture in one out of eight rebound participants.

The findings suggest that rebound symptoms could be partially driven by the robust cellular immune response to residual viral RNA throughout the respiratory tract, rather than an impaired immune response allowing viral replication, according to the authors. Larger, more detailed epidemiologic studies are needed to further understand the clinical importance and epidemiologic consequences of COVID-19 rebound, the authors write. The authors note that the current data support the need for isolation in symptomatic rebound persons and the need to evaluate, in a clinical trial, longer courses of Paxlovid in immunocompromised individuals where the immune response may be ineffective.

More Articles

• Articles from Stanford's Science Department You and Others Might Find of Interest
• A New Study: Sex Differences in Pharmacokinetics Predict Adverse Drug Reactions in Women
• Five Articles From British Vogue Concerning Stay-At-Home Grooming - Including for Grey Hair
• Skydivers Don’t Need Parachutes, Scientists Don’t Actually Find: Be wary of parachute journalism. And also parachute research.
• Journalists Trying To Help Readers Cope May Mislead on Holiday-Suicide Myth
• Finally? NIH to Evaluate Effectiveness of Male Contraceptive Skin Gel; Researchers Plan to Enroll 420 Couples in Clinical Trial
• Treating Blood Pressure to a Lower Goal Particularly For Those Over the Age of 50
• National Institutes of Health & The Genetics of the 2014 Ebola Outbreak, WHO and Clinical Trials
• Isn’t There Any Mystery Left to Being Apart? The Obsession to Keeping in Touch With Those Out of Sight
• Rancho Bernardo Heart and Disease Study Observes 40th Year