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Grand RoundsWeekly Evidence Brief

Infectious Diseases

Edition

30-Second Takeaway

  • Prioritize **rapid, high-coverage oseltamivir prophylaxis** in nursing home influenza outbreaks to cut near-term hospitalizations.
  • Expect **moderate influenza VE** in chronic respiratory disease and invest in raising vaccination coverage.
  • Use **modern molecular and genomic tools** to detect and track MDR-TB and multidrug-resistant malaria early.

Week ending April 4, 2026

Targeted antiviral use, resistance surveillance, and diagnostic advances across high-risk infections

Rapid, high-coverage oseltamivir chemoprophylaxis lowers hospitalization in nursing home influenza outbreaks

JAMA INTERNAL MEDICINEMar 30, 2026

This retrospective target trial emulation analyzed 35,086 resident-trial observations across 404 US nursing home influenza outbreaks. Intensive chemoprophylaxis meant oseltamivir for ≥70% of eligible residents within 2 days of outbreak detection. Compared with less-intensive prophylaxis, intensive use reduced 14-day hospitalization risk (RD −0.96%; RR 0.79; 95% CI 0.64–0.96). There was no significant effect on all-cause mortality at 14 or 30 days.

Rapidly expanding MDR Ural 4.2.1 TB clade spreads from Russia and Moldova across Europe and Asia

NATURE COMMUNICATIONSApr 1, 2026

Interrogation of ~200,000 global M. tuberculosis genomes identified a 1,604-strain multidrug-resistant lineage 4.2.1/Ural clade. This clade carries conserved resistance-conferring mutations and is expanding faster than other lineage 4.2.1/Ural clades. Phylogeographic reconstruction points to the Russian Federation as the most likely origin, with multiple exports to European and Asian countries. Its broad dispersal and apparent fitness make it a high-priority MDR-TB threat for regional programs and global TB strategies.

MDRmDx GeneXpert-compatible cartridge broadens rifampicin and isoniazid resistance detection from sputum

JOURNAL OF CLINICAL MICROBIOLOGYMar 30, 2026

MDRmDx is a low-complexity nucleic acid amplification assay for 10-color GeneXpert instruments that detects M. tuberculosis plus rifampicin and isoniazid resistance. Analytical limits of detection for M. tuberculosis and rifampicin susceptibility were similar to Xpert MTB/RIF Ultra. MDRmDx identified all rpoB mutations with ≥0.5% global prevalence, including I491F and several not detected by Ultra. In frozen sputum enriched for smear-negative and drug-resistant samples, sensitivity exceeded 90% for M. tuberculosis and was near-perfect for rifampicin and isoniazid resistance.

Broad-lineage Lassa virus lateral flow RDT shows markedly improved analytical sensitivity

JOURNAL OF CLINICAL MICROBIOLOGYMar 30, 2026

Investigators developed a lateral flow rapid diagnostic test targeting Lassa virus nucleoprotein using new monoclonal antibody pairs. In 60 human serum and plasma specimens, the final assay demonstrated 100% specificity. It detected multiple genetically diverse Lassa virus strains, though with lineage-dependent sensitivity differences. Compared with the ReLASV Pan-Lassa Antigen Rapid Test, recombinant antigen testing showed ~64-fold higher analytical sensitivity.

References

Numbered in order of appearance. Click any reference to view details.

Additional Reads

Optional additional studies from this edition.

Edition context

Clinical signal

  • Intensive oseltamivir chemoprophylaxis in nursing homes reduces influenza-related hospitalizations but not short-term mortality, informing LTC outbreak algorithms.
  • Genomic and cartridge-based innovations improve MDR-TB detection while a rapidly expanding MDR Ural 4.2 clade underscores the need for global surveillance.
  • New Lassa RDTs and mpox IgA/IgG profiles support earlier and covert infection detection in resource-limited and HIV-affected communities.