BACKGROUND:

The relative ability of neuraminidase inhibitors (NAIs) to reduce household influenza transmission when given to index patients is not established.

OBJECTIVES:

To compare daily secondary infection rates (SIR) of influenza A (A/H1pdm and A/H3) and B in households of index patients treated with oseltamivir, zanamivir, laninamivir, or peramivir.

PATIENTS/METHODS:

This Japanese, single-center, prospective, observational study (UMIN-CTR: UMIN000024650) enrolled index patients with confirmed influenza who were treated with an NAI during 6 influenza seasons (2010-2016). Secondary infection patients were household members diagnosed with the same influenza subtype 1-7 days after onset in the index patient. Daily SIR was calculated using a modified Reed-Frost model. The rate of household members with secondary infection and proportion of households with any secondary infection were also calculated.

RESULTS:

Index patients with influenza A (n=1146) or B (n=661) were enrolled (~3400 total index and secondary patients). Daily SIR for all virus subtypes was highest when oseltamivir was used (eg, unadjusted estimate: type A, 1.47% vs 0.71%-1.13%; type B, 1.30% vs 0.59%-0.88%). Pairwise comparisons revealed significant differences in daily SIR between NAIs for influenza type A, type B, and subtype A/H3; eg, for type A, SIR was significantly higher with oseltamivir than with peramivir or zanamivir. The rate of household members with secondary infection and proportion of households with any secondary infection also varied between NAIs.

CONCLUSIONS:

NAIs differed in their ability to reduce household influenza transmission; transmission was highest with oseltamivir. Physicians may consider effects on household transmission when deciding which NAI to prescribe.