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Q In household contacts (HHCs) (after index influenza [flu] patients received oseltamivir), is postexposure prophylaxis (PEP) more effective than oseltamivir treatment at the time of illness (expectant treatment) for preventing flu transmission?
Clinical impact ratings GP/FP/Primary care ★★★★★☆☆ Infectious diseases ★★★★★★☆
METHODS
Design:
cluster (household level) randomised controlled trial.
Allocation:
Blinding:
unblinded.*
Follow up period:
30 days.
Setting:
households in Europe and North America.
Participants:
812 HHCs (age range 1–83 y, 55% girls/women) of index patients with a flu like illness during a community flu outbreak. Eligible households had 3–8 members, including ⩾1 index patient and ⩾2 eligible contacts ⩾1 year of age. Exclusion criteria included pregnancy, breastfeeding, and cancer.
Intervention:
households were allocated to PEP (n = 138 households with 410 HHCs) or expectant treatment (n = 139 households with 402 HHCs). All index patients and HHCs developing illness in the expectant treatment group received oseltamivir treatment (adults and adolescents 75 mg capsules; and children 30–60 mg suspension twice/day) for 5 days. HHCs in the PEP group received the same dosage as for treatment but given once/day.
Outcome:
number of households with ⩾1 secondary patient who had laboratory confirmed flu during the 10 day period after the start of treatment in the index patient.
Patient follow-up:
97% (intention to treat analysis).
MAIN RESULTS
Fewer households in the PEP group than in the expectant treatment group had ⩾1 secondary contact with laboratory confirmed flu (table).
Postexposure prophylaxis v expectant treatment with oseltamivir at the time of developing influenza in household contacts (after treatment of all index influenza patients with oseltamivir)*
CONCLUSION
In household contacts (after treatment of all index influenza [flu] patients with oseltamivir), postexposure prophylaxis was more effective than treatment with oseltamivir at the time of developing illness for reducing flu transmission in households.
Abstract and commentary also appear in ACP Journal Club.
Commentary
The study by Hayden et al showed that oseltamivir is effective for reducing flu transmission from an infected family member to others in the household. The efficacy was greatest in a subgroup of HHCs who were not infected at baseline (relative risk reduction or protective efficacy 79%, 95% CI 41 to 92, number needed to treat 6) compared with that in the overall intention to treat population (table).
A number of other practical considerations are worth noting about the clinical use of oseltamivir or zanamivir (another neuraminidase inhibitor with proven effectiveness). Firstly, the avian flu, which has peppered most countries in southeast Asia and China, should be susceptible to these 2 drugs, and their use could have reduced the corresponding mortality and morbidity that occurred. Secondly, the severe acute respiratory syndrome, caused by a variant of the coronavirus group, may be difficult to distinguish from flu. Both can occur at the same time in a population. It is important to note that flu is treatable whereas the severe acute respiratory syndrome is not.
Neuraminidase inhibitors should be part of a comprehensive flu prevention and treatment program. The drugs are not just for the elderly, but for the whole population. We are all “at risk” of sinusitis, a prolonged illness with loss of time from work and possibly death. However, it is important to remember that as good as these drugs are, they are a supplement to flu vaccination. The flu vaccine has been shown to have a 50–90% protective efficacy depending on the vaccine strain and population group.1 The vaccine also reduces hospitalization for pneumonia as well as reducing the risk of heart failure, stroke, and death from all causes––not insignificant positive side effects.