Paxlovid tied to 34% lower risk of hospitalization in adolescent COVID patients

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White Paxlovid pills — *Ruben Ramos / iStock*

Treatment with the antiviral drug nirmatrelvir-ritonavir (Paxlovid) was linked to a 34% lower risk of all-cause hospitalization among COVID-19 patients aged 12 to 17 years, University of Hong Kong researchers report in Nature Communications.

The investigators conducted an observational study that incorporated design characteristics from a hypothetical, randomized controlled trial among 49,378 non-hospitalized pediatric COVID-19 patients infected with the SARS-CoV-2 Omicron variant. Patients received Paxlovid within 5 days of symptom onset or diagnosis from March 2022 to February 2023.

Paxlovid user outcomes were compared with those of an equal number of control patients. Most participants in both groups had limited underlying medical conditions, and about 75% were fully vaccinated and/or boosted against COVID-19.

In the United States, everyone aged 12 and older who weighs at least 88 pounds, has mild to moderate COVID-19, and is at high risk for severe illness is eligible for Paxlovid treatment.

No safety concerns reported

Cumulative all-cause hospitalization rates were 0.45% in the Paxlovid group and 0.68% among controls. COVID-19 accounted for 200 of 211 hospitalizations (94.8%) among Paxlovid recipients and 215 of 332 hospitalizations (64.8%) among controls.

This target trial emulation study confirmed the effectiveness of nirmatrelvir/ritonavir in reducing all-cause hospitalization risk among non-hospitalized paediatric patients with SARS-CoV-2 Omicron variant infection.

Paxlovid therapy was tied to lower all-cause hospitalization by 28 days (absolute risk reduction, 0.23%; relative risk, 0.66). No participants died, experienced poor outcomes, or became sicker in the hospital.

"This target trial emulation study confirmed the effectiveness of nirmatrelvir/ritonavir in reducing all-cause hospitalization risk among non-hospitalized paediatric patients with SARS-CoV-2 Omicron variant infection," the study authors concluded. "No safety signals were reported following outpatient nirmatrelvir/ritonavir use among paediatric patients aged 12–17 years."

Household study suggests infants may spread C difficile

News brief

Chris Dall, MA

Parent changing diaper — Anastasiia Stiahailo / iStock

A small longitudinal household study suggests sharing of Clostridioides difficile strains is a common event in families caring for an infant, US researchers reported today in Open Forum Infectious Diseases.

For the study, a team led by researchers from Rainbow Babies and Children's Hospital in Cleveland, Ohio, recruited 30 families of healthy infants at their child's 4-month well child visit, collected stool samples or rectal swabs from the infants and their parents every 2 weeks, and followed up on the families longitudinally until the infants were 9 months old.

With infants known to asymptomatically excrete C difficile throughout the first 2 years of life, the researchers wanted to measure the frequency in which C difficile excreted by infants can be identified in a parent, which could help determine the role infants might play in the spread of the disease in the community.

Shared strains found in 61% of households

Samples were collected from 33 infants (three sets of twins), 30 mothers, and 19 fathers. C difficile was isolated in at least one member in 28 of 30 families, though no parent or infant was diagnosed as having C difficile infection (CDI). A total of 225 organisms were cultivated from the samples, and 191 were recovered and strain-typed.

C difficile strains were shared in 17 of the 28 families harboring C difficile, with three families found to share two separate strains. The infant and at least one adult family member were implicated in 17 of 20 instances of strain sharing, and, in at least 13 of these, the strain was detected in the infant first. Excretion of shared strains was persistent.

Although they were unable to demonstrate the directionality of C difficile transmission with certainty, the study authors say the data from the study support adding asymptomatically excreting infants and their families to the list of potential sources of community-associated CDI.

"It is likely that community reservoirs of C. difficile are multiple; controlling intra-familial sharing of the organism in households caring for an infant may prove to be one of several interventions necessary to control this threat to the public health," they wrote.

FDA expands RSV vaccine use to adults aged 50 to 59

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Stephanie Soucheray, MA

The Food and Drug Administration (FDA) has expanded the age indication for GSK’s Arexvy respiratory syncytial virus (RSV) vaccine to include adults aged 50 to 59 years at increased risk for complications from the virus.

In a press release, GSK said more than 13 million Americans fall into this category. The vaccine was initially approved last fall for use in all adults aged 60 and older.

"When it comes to the risks associated with RSV, age is just a number, an important number, but not the only factor to consider," said Ann R. Falsey, MD, of the University of Rochester School of Medicine in the press release. "Many adults in this age group have underlying health conditions that place them at increased risk for serious illness with RSV infection compared with those without these conditions."

When it comes to the risks associated with RSV, age is just a number, an important number, but not the only factor to consider

GSK said recent studies have shown RSV causes approximately 42,000 annual hospitalizations in adults aged 50 to 59, especially in those with chronic obstructive pulmonary disease, asthma, heart failure, and diabetes.

"Today's approval reflects the importance of broadening the benefits of RSV immunization to adults aged 50-59 who are at increased risk," said Tony Wood, PhD, GSK’s chief scientific officer. "For those with underlying medical conditions, RSV can have serious consequences."

The drugmaker said trials evaluating the immunogenicity and safety of the vaccine in adults aged 18 to 49 at increased risk for severe illness and adults aged 18 and older with weakened immune systems are expected in the coming months.