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What interventions might reduce the impact of a pandemic?
Overview
Researchers from the Los Alamos National Laboratory evaluated the effectiveness
of different intervention strategies for a flu pandemic by developing a model
that represents the US population and tests different properties of a potential
pandemic flu virus. They found that, depending on the contagiousness of the
virus, a variety of approaches could reduce the number of flu cases to fewer
than that of an annual flu season.
Mathematical modeling has significant limitations and these approaches cannot provide substantial evidence for effectivness claims.
Method
The scientists simulated a virtual outbreak on computers at the Los Alamos
National Laboratory. The researchers tested different interventions: distributing
antiviral treatments to infected individuals and others near them
to reduce symptoms and susceptibility; vaccinating people, possibly children
first, with either 1 or 2 shots of a vaccine not well matched to the strain
that may emerge; social distancing, such as restricting travel and
quarantining households; and closing schools.
No Interventions
The results showed that, with no intervention, a pandemic flu with low
contagiousness could peak after 117 days and infect about 33% of the US
population. A highly contagious virus could peak after 64 days and infect
about 54% of the population.
Using Interventions
The researchers then compared what might happen in scenarios involving the use
of different interventions.
When the simulated virus was less contagious, the 3 most effective single
measures included: distributing several million courses of antiviral treatment
to targeted groups 7 days after a pandemic alert; school
closures; and vaccinating 10 million people per week with 1 dose of a
poorly matched vaccine.
The results also showed that vaccinating school children first is more effective
than random vaccination when the vaccine supply is limited. Regardless of
contagiousness, social distancing measures, alone, had little effect.
But when the virus was highly contagious, all single-intervention strategies
left nearly half the population infected. In this instance, the only measures
that reduced the number of cases to below the annual flu rate involved a
combination of at least three different interventions, including a minimum of
182 million courses of antiviral treatment.
Learn about the role vaccines will play in the event of a pandemic.
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