Tools for Practice Outils pour la pratique


#176 Stockpile, use during outbreaks, re-stock and repeat


CLINICAL QUESTION
QUESTION CLINIQUE
How effective are oseltamivir and zanamivir at decreasing post-exposure transmission of influenza?


BOTTOM LINE
RÉSULTAT FINAL
For institutionalized seniors, six weeks of oseltamivir or 14 days of zanamivir or will prevent one additional influenza case in every 25-27 treated. For every 7-8 householdgiven post-exposure prophylaxis (PEP)one household will avoid anyone developing influenza.  



CFPCLearn Logo

Reading Tools for Practice Article can earn you MainPro+ Credits

La lecture d'articles d'outils de pratique peut vous permettre de gagner des crédits MainPro+

Join Now S’inscrire maintenant

Already a CFPCLearn Member? Log in

Déjà abonné à CMFCApprendre? Ouvrir une session



EVIDENCE
DONNÉES PROBANTES
Mostly unpublished, industry-sponsored, Randomized Controlled Trials (RCTs)1 (from 1990s) and two systematic reviews.2,3 Results all lab confirmed, symptomatic influenza. 
  • Institutionalized seniors: 
    • ZanamivirPEP during influenza outbreak (ten cases or 10% with influenza): 
      • Two RCTs of 14 days of zanamivir 10 mg/day versus rimantadine (was standard of care) or placebo in 385 (98% vaccinated) and 489 (9% vaccinated) residents, respectively. 
        • Influenza at 15 days:  
          • 2.9% versus 7.4% (rimantidine); statistically significant. 
          • 6.3% versus 9.2% (placebo); not statistically different. 
            • Pooled (by authors): 4.6% versus 8.3%, Number Needed to Treat (NNT)=27.  
    • Oseltamivir: Six weeks of oseltamivir 75 mg/day or placebo in 548 (69% vaccinated) patients when influenza “noted in the community.”  
      • Influenza at eight weeks0.3% versus 4.4% (placebo), NNT=25. 
  • Households 
    • Three clustered (by household) placebo-controlled RCTs when household member diagnosed with influenza-like illnessContacts mean ages 24-33 years (children excluded)<15% vaccinated:   
      • Zanamivir: Ten days of zanamivir or placebo; households with ≥1 new influenza case at 11 days (pooled): 1,4 
        • 4.6% versus 20.5% (placebo), NNT=7. 
      • Oseltamivir: Seven days of oseltamivir 75 mg/day or placebo; households with ≥1 new influenza case at 21 days: 1,5    
        • 2.1% versu14.6% (placebo), NNT=8. 
  • Other outcomes:  
    • Hospitalizations: No difference.2,3  
    • Adverse effects: Multiple analyses performed.3 
      • Oseltamivir: Psychiatric events Number Needed to Harm (NNH)=95; headache NNH=32; nausea NNH=25.2,3 
      • Zanamivir: No difference in treatment trials3 
  • Limitations: Inconsistent outcome definitionsselective reporting.2 
CONTEXT:  
  • Canada stockpiles ~60 million doses of primarily oseltamivir, ~50% expire before use.6 
  • Guidelines recommend:  
    • Closed facility outbreaks:  
      • Treating index case and vaccinating the unvaccinated7  
      • PEP for 14 days or seven days after the onset of symptoms in the last infected person, whichever is longer.8 
    • Household contact: PEP only if vaccination contra-indicated.7 


Latest Tools for Practice
Derniers outils pour la pratique

#367 Oral Calcitonin Gene-related Peptide Antagonists: A painfully long name for the acute treatment of migraines

What are the risks and benefits of ubrogepant for the acute treatment of episodic migraines?
Read Lire 0.25 credits available Crédits disponibles

#366 Looking for Closure: Managing simple excisions or wounds efficiently

What are some options for efficiency in wound closure?
Read Lire 0.25 credits available Crédits disponibles

#365 Shrooms for Glooms: Evidence for psilocybin for depression

What are the benefits and harms of psilocybin for treatment-resistant/recurrent depression?
Read Lire 0.25 credits available Crédits disponibles

This content is certified for MainPro+ Credits, log in to access

Ce contenu est certifié pour les crédits MainPro+, Ouvrir une session


Author(s)
Auteur(s)
  • Michael R Kolber BSc MD CCFP MSc
  • Christina Korownyk MD CCFP

1. Neuraminidase inhibitors for preventing and treating influenza in healthy adults and children. Available at: http://dx.doi.org/10.5061/dryad.77471. Last Accessed: October 14, 2016. RCTs referenced: NAIA3003, NAIA3004, WV15825. NAI30031, NAI30010, WV15799.

2. Jefferson T, Jones MA, Doshi P, et al. Cochrane Database Syst Rev. 2014; 4:CD008965.

3. Heneghan CJ, Onakpoya I, Jones MA, et al. Health Technol Assess. 2016; 20(42):1-242.

4. Hayden FG, Gubareva LV, Monto AS, et al. N Engl J Med. 2000; 343:1282-9.

5. Welliver R, Monto AS, Carewicz O, et al. JAMA. 2001; 285:748-54.

6. Public Health Agency of Canada. Available at: http://www.phac-aspc.gc.ca/cpip-pclcpi/assets/pdf/annex_e-eng.pdf. Last Accessed: October 20, 2016.

7. Aoki FY, Allen UD, Stiver HG, et al. Can J Infect Dis Med Microbiol. 2013; 24:Suppl C:1C-15C.

8. Harper SA, Bradley JS, Englund JA, et al. Clin Infect Dis. 2009; 48:1003-32.

Authors have no conflicts of interest to declare. We wish to thank Dr. T. Jefferson for advising us of the location of the unpublished reports.