Economic analysis of the use of facemasks during pandemic (H1N1) 2009

Abstract

A large-scale pandemic could cause severe health, social, and economic impacts. The recent 2009 H1N1 pandemic confirmed the need for mitigation strategies that are cost-effective and easy to implement. Typically, in the early stages of a pandemic, as seen with pandemic (H1N1) 2009, vaccines and antivirals may be limited or non-existent, resulting in the need for non-pharmaceutical strategies to reduce the spread of disease and the economic impact. We construct and analyze a mathematical model for a population comprised of three different age groups and assume that some individuals wear facemasks. We then quantify the impact facemasks could have had on the spread of pandemic (H1N1) 2009 and examine their cost effectiveness. Our analyses show that an unmitigated pandemic could result in losses of nearly $832 billion in the United States during the length of the pandemic. Based on present value of future earnings, hospital costs, and lost income estimates due to illness, this study estimates that the use of facemasks by 10%, 25%, and 50% of the population could reduce economic losses by $478 billion, $570 billion, and $573 billion, respectively. The results show that facemasks can significantly reduce the number of influenza cases as well as the economic losses due to a pandemic.

Introduction

On June 11, 2009, the World Health Organization (WHO) declared the outbreak of novel influenza A (H1N1) (referred to as pandemic (H1N1) 2009 per WHO nomenclature) a pandemic. The emergence of an unexpected or novel strain of influenza poses problems in combating the spread of infection. Vaccines are typically the first line of defense against influenza viruses (Germann et al., 2006), however, in the case of novel viruses vaccines may not be readily available. In addition to vaccines, public health campaigns encouraging good hygiene have been used to reduce the spread of influenza.

During the pandemic (H1N1) 2009 outbreak several non-pharmaceutical mitigation strategies were used including school closures, social distancing, and facemasks (Condon and Sinha, 2009). Influenza spreads through person-to-person contact via airborne particles as well as by direct and indirect (e.g., via fomites) contacts. Several studies have shown that facemasks can be an effective mitigation strategy. A recent study on facemasks and hand hygiene showed a 10–50% transmission reduction for influenza-like illnesses (Aiello et al., 2010). Other studies have also shown that facemasks cannot only act as a barrier (Del Valle et al., 2010) but they can redirect and decelerate exhaled air flows to prevent them from entering the breathing zones of others (Tang and Settles, 2009). Several laboratory studies on mask effectiveness have shown that N95 respirators are 21.5% effective in protecting against the inhalation of nanoparticles, while surgical masks were only 2.4% effective (an Lee et al., 2008). However, a study by Loeb et al. (2009) found that surgical masks and N95 respirators offered about the same percentage of protection for nurses in hospitals. Although several studies have shown that both surgical masks and N95 provide similar protection against influenza, a recent editorial by Killingley (2011) discusses two studies and argues that the results are still inconclusive and that more research is needed. For our model we will focus on N95 respirators since we are interested in analyzing optimal interventions, however, our analyses may be applicable to surgical masks based on Loeb et al. (2009) results.

Using a mathematical model, Tracht et al. (2010) analyzed the effectiveness of facemasks in reducing the spread of pandemic (H1N1) 2009. They compared the impact that surgical and N95 masks could have on reducing the spread of influenza. Their results showed that facemasks can be an effective intervention strategy for mitigating an airborne disease. We expand upon that model by dividing the population into three age groups and quantifying the impact of facemasks (also referred to as N95 respirators) have on the spread of the disease as well as their cost effectiveness.