Speaker
Description
Influenza is one of the respiratory diseases, and symptoms can be alleviated by treating with antiviral agents such as baloxavir, oseltamivir, laninamivir, and zanamivir. It is known to have high household transmission risk and the risk differs by age and treatment timing \cite{hirotsu_effect_2019}. Baloxavir is particularly effective at reducing secondary attack rate (SAR), and serial interval (SI)—the time between symptom onset in primary and secondary case—also varies with treatment timing. However, there is a lack of prior research analyzing the relationship between SI and SAR. This study aims to compare household SAR by individual characteristics and explain how SAR varies based on treatment timing by estimating SI distribution.
A household survey was conducted in Japan (October 2018–February 2019), enrolling 915 housholds. Index cases untreated or treated and houehold contacts were stratified by age and treatment timing, and SARs and odds ratios (ORs) were calculated. Assuming the SI distribution of baloxavir-treated cases reflects infectiousness, likelihood-based models were defined to estimate the reduction effect due to baloxavir on SI and SAR by the treatment timing.
SAR was highest in the 0–14 age and treatment initiated within 48 hours of symptom onset was effective in reducing risk. Baloxavir (OR=0.62) showed greater preventive effects than oseltamivir, and earlier treatment produced greater shortening of the SI, which corresponded to lower SAR within households.
Bibliography
@article{hirotsu_effect_2019,
title = {The effect of neuraminidase inhibitors on household transmission in {Japanese} patients with influenza {A} and {B} infection: {A} prospective, observational study},
volume = {13},
issn = {1750-2640, 1750-2659},
shorttitle = {The effect of neuraminidase inhibitors on household transmission in {Japanese} patients with influenza {A} and {B} infection},
url = {https://onlinelibrary.wiley.com/doi/10.1111/irv.12590},
doi = {10.1111/irv.12590},
abstract = {Background
The relative ability of neuraminidase inhibitors (
NAI
s) 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
:
UMIN
000024650) 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 ({\textasciitilde}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
NAI
s for influenza type A, type B, and subtype A/H3; for example, 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
NAI
s.
Conclusions
Neuraminidase inhibitors 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.},
language = {en},
number = {2},
urldate = {2026-03-13},
journal = {Influenza and Other Respiratory Viruses},
author = {Hirotsu, Nobuo and Saisho, Yutaka and Hasegawa, Takahiro},
month = mar,
year = {2019},
pages = {123--132},
}
