Research Summary: Can Antiviral Drugs Contain Pandemic Influenza Transmission?


Antiviral drugs dispensed during the 2009 influenza pandemic generally failed to
contain transmission. This poses the question of whether preparedness for a
future pandemic should include plans to use antiviral drugs to mitigate

Simulations using a standard transmission model that allows for infected arrivals
and delayed vaccination show that attempts to contain transmission require
relatively few antiviral doses. In contrast, persistent use of antiviral drugs
when the reproduction number remains above 1 use very many doses and are
unlikely to reduce the eventual attack rate appreciably unless the stockpile is
very large. A second model, in which the community has a household structure,
shows that the effectiveness of a strategy of dispensing antiviral drugs to
infected households decreases rapidly with time delays in dispensing the
antivirals. Using characteristics of past pandemics it is estimated that at
least 80% of primary household cases must present upon show of symptoms
to have a chance of containing transmission by dispensing antiviral drugs to
households. To determine data needs, household outbreaks were simulated with
50% receiving antiviral drugs early and 50% receiving antiviral
drugs late. A test to compare the size of household outbreaks indicates that at
least 100–200 household outbreaks need to be monitored to find evidence
that antiviral drugs can mitigate transmission of the newly emerged virus.

Use of antiviral drugs in an early attempt to contain transmission should be part
of preparedness plans for a future influenza pandemic. Data on the incidence of
the first 350 cases and the eventual attack rates of the first 200 hundred
household outbreaks should be used to estimate the initial reproduction number
R and the effectiveness of antiviral drugs to mitigate
transmission. Use of antiviral drugs to mitigate general transmission should
cease if these estimates indicate that containment of transmission is


Publisher: Public Library of Science

Date Published: 28-March-2011

Author(s): Becker N., Wang D.


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