July 30, 2026

RSV

Impact of Nirsevimab in Its Second Season on Respiratory Syncytial Virus and Non-RSV Admissions in Children Under 5
These are the results of a retrospective study conducted at a tertiary center in Tarragona, Spain. They included children under 5 hospitalized with acute lower respiratory tract infections (ALRTI) during the RSV seasons between 2018 and 2025 (excluding the 2020-2021 season due to the coronavirus disease pandemic). Among 1,384 ALRTI hospitalizations, 661were RSV-confirmed and 375 required PICU admission. After nirsevimab rollout, hospital admissions due to RSV decreased from 5.04 to 2.5 per 1000 ( P < 0.001), hospitalizations due to non-RSV decreased from 5.1 to 3.54 per 1000 children <5 years ( P = 0.004) and PICU admissions due to ALRTI (RSV and non-RSV) declined from 2.9 to 1.3 per 1,000 children ( P < 0.001). Universal nirsevimab immunization was associated with sustained reductions in RSV-related hospitalizations and critical illness, but also in hospitalizations due to other respiratory viruses.

COVID: Early Viral Phase

Remdesivir and All-Cause Graft Loss Among Kidney Transplant Recipients With Symptomatic COVID-19
Retrospective cohort study emulated a target trial using observational data from five hospitals within the Johns Hopkins Health System. Adult KT recipients (aged ≥18 years) with a functioning allograft and symptomatic COVID-19 from March 2020 through January 2024 were eligible. Patients who received anti–SARS-CoV-2 monoclonal antibodies, nirmatrelvir-ritonavir, and/or molnupiravir were excluded. Among 432 KT recipients with symptomatic COVID-19 (median age, 57 years [IQR, 46-66 years]; 248 [57.4%] were male), 177 (41.0%) initiated early remdesivir and 255 (59.0%) received no remdesivir. Over one year of follow-up, early remdesivir initiation vs no remdesivir was associated with a lower risk of ACGL (HR, 0.53; 95% CI, 0.31-0.92) and CVEs (HR, 0.58; 95% CI, 0.35-0.98) after CCW adjustment. The association between early initiation of remdesivir and lower risk of all-cause mortality did not reach statistical significance (HR, 0.51; 95% CI, 0.24-1.06) or Long COVID (HR, 0.65; 95% CI, 0.21-2.05) in the weighted analysis.

COVID: The Late Phase/PASC/Long COVID

Skeletal Muscle Properties in Long COVID and ME/CFS Differ From Those Induced by Bed Rest
This study compared whole-body exercise responses and skeletal muscle adaptations after strict 60-day bed rest in healthy people with those in Long COVID and ME/CFS patients, and healthy age- and sex-matched controls. Patients with Long COVID and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) suffer from post-exertional malaise. The accompanying physical inactivity may contribute to a lower aerobic capacity and may explain skeletal muscle adaptations in these patients. Bed rest alters respiratory and cardiovascular responses to maximal exercise, which are dissimilar in patients. Bed rest causes muscle atrophy without altering fiber type. Both patient groups have more glycolytic fibers, and ME/CFS patients display type I-specific atrophy. Only after bed rest is oxidative phosphorylation capacity associated with maximal oxygen uptake. As skeletal muscle characteristics differ between patients and healthy individuals after bed rest, physical inactivity cannot solely explain the lower exercise capacity and skeletal muscle adaptations in long COVID and ME/CFS patients.

Loss of Vesicular Monoamine Transporter 2 in Striatum of Long COVID and Relationship to Neuropsychiatric Symptoms
This case–control study included 24 adults with Long COVID and 24 age-matched healthy controls, and the healthy control sample was extended to 43 for exploratory analyses. Primary outcome was comparison of (+)[11C]DTBZ binding potential (BPND), PET measure of VMAT2 binding, between Long COVID and control groups across ventral striatum, dorsal putamen, and dorsal caudate. Secondary outcomes were associations of regional (+)[11C]DTBZ BPND with neuropsychiatric measures (apathy, anhedonia, motor retardation) in Long COVID. (+)[11C]DTBZ BPND was significantly lower in 24 individuals with Long COVID vs 24 age-matched healthy controls (linear mixed effects model, P = 4 × 10−5; vs 43 controls, P = 6 × 10−4). Apathy, motor slowing (secondary outcomes) and memory decline (exploratory outcome) correlated with lower (+)[11C]DTBZ BPND in ventral striatum, dorsal putamen and caudate, respectively (|r| = 0.48–0.58, P = 0.0029–0.018). Findings of reduced VMAT2 binding may reflect reduced dopaminergic terminal integrity in Long COVID. Loss of dopamine nerve terminals may be contributing to symptom correlates of apathy, motor slowing and memory decline suggesting improved function of dopaminergic synapses as a new therapeutic direction to treat Long COVID.