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Mathematical modeling of the effectiveness of facemasks in reducing the spread of novel influenza A (H1N1).

Tracht SM, Del Valle SY, Hyman JM - PLoS ONE (2010)

Bottom Line: To estimate the parameter values used for the effectiveness of facemasks, we used available data from studies on N95 respirators and surgical facemasks.The results show that if N95 respirators are only 20% effective in reducing susceptibility and infectivity, only 10% of the population would have to wear them to reduce the number of influenza A (H1N1) cases by 20%.We can conclude from our model that, if worn properly, facemasks are an effective intervention strategy in reducing the spread of pandemic (H1N1) 2009.

View Article: PubMed Central - PubMed

Affiliation: Energy and Infrastructure Analysis Group, Decisions Applications Division, Los Alamos National Laboratory, Los Alamos, New Mexico, United States of America. samantha.tracht@gmail.com

ABSTRACT
On June 11, 2009, the World Health Organization declared the outbreak of novel influenza A (H1N1) a pandemic. With limited supplies of antivirals and vaccines, countries and individuals are looking at other ways to reduce the spread of pandemic (H1N1) 2009, particularly options that are cost effective and relatively easy to implement. Recent experiences with the 2003 SARS and 2009 H1N1 epidemics have shown that people are willing to wear facemasks to protect themselves against infection; however, little research has been done to quantify the impact of using facemasks in reducing the spread of disease. We construct and analyze a mathematical model for a population in which some people wear facemasks during the pandemic and quantify impact of these masks on the spread of influenza. To estimate the parameter values used for the effectiveness of facemasks, we used available data from studies on N95 respirators and surgical facemasks. The results show that if N95 respirators are only 20% effective in reducing susceptibility and infectivity, only 10% of the population would have to wear them to reduce the number of influenza A (H1N1) cases by 20%. We can conclude from our model that, if worn properly, facemasks are an effective intervention strategy in reducing the spread of pandemic (H1N1) 2009.

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Related in: MedlinePlus

Schematic relationship between mask wearing individuals and non-mask wearing individuals for pandemic (H1N1) 2009.The arrows that connect the boxed groups represent the movement of individuals from one group to an adjacent one. Non-mask wearing susceptible individuals (S) can either become exposed (E) or susceptible wearing a mask . Non-mask wearing exposed individuals (E) can either become infectious non-mask wearing (I) or mask wearing exposed (). Non-mask wearing infectious individuals (I) can either recover (R), die (D), or become infectious wearing a mask (). Mask wearing susceptible individual () can either become an exposed mask wearer () or a non-mask wearing susceptible (S). Mask wearing exposed individuals () can either become an infectious mask wearer () or a non-mask wearing exposed individual (E). A mask wearing infectious individual () can either recover (R), die (D), or stop wearing the mask while they are still infectious (I).
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pone-0009018-g001: Schematic relationship between mask wearing individuals and non-mask wearing individuals for pandemic (H1N1) 2009.The arrows that connect the boxed groups represent the movement of individuals from one group to an adjacent one. Non-mask wearing susceptible individuals (S) can either become exposed (E) or susceptible wearing a mask . Non-mask wearing exposed individuals (E) can either become infectious non-mask wearing (I) or mask wearing exposed (). Non-mask wearing infectious individuals (I) can either recover (R), die (D), or become infectious wearing a mask (). Mask wearing susceptible individual () can either become an exposed mask wearer () or a non-mask wearing susceptible (S). Mask wearing exposed individuals () can either become an infectious mask wearer () or a non-mask wearing exposed individual (E). A mask wearing infectious individual () can either recover (R), die (D), or stop wearing the mask while they are still infectious (I).

Mentions: Following the approached developed in [15], the population is divided into two subgroups: a mask wearing group (subscript m) and a non-mask wearing group. People move back and forth between the mask and non-mask groups based on the number of individuals infected with pandemic (H1N1) 2009. Individuals in each activity group are characterized by their epidemiological status: susceptible, denoted by S and , exposed, denoted by E and (i.e., people who are infected but not yet fully contagious), and infectious individuals, I and . Definitions of the eight epidemiological classes are summarized in Table 1 and the transfers are shown diagrammatically in Figure 1. Because we are evaluating the effectiveness of masks in a single influenza period, we use a closed system with no migration in or out, and births and natural deaths are not included in the model.


Mathematical modeling of the effectiveness of facemasks in reducing the spread of novel influenza A (H1N1).

Tracht SM, Del Valle SY, Hyman JM - PLoS ONE (2010)

Schematic relationship between mask wearing individuals and non-mask wearing individuals for pandemic (H1N1) 2009.The arrows that connect the boxed groups represent the movement of individuals from one group to an adjacent one. Non-mask wearing susceptible individuals (S) can either become exposed (E) or susceptible wearing a mask . Non-mask wearing exposed individuals (E) can either become infectious non-mask wearing (I) or mask wearing exposed (). Non-mask wearing infectious individuals (I) can either recover (R), die (D), or become infectious wearing a mask (). Mask wearing susceptible individual () can either become an exposed mask wearer () or a non-mask wearing susceptible (S). Mask wearing exposed individuals () can either become an infectious mask wearer () or a non-mask wearing exposed individual (E). A mask wearing infectious individual () can either recover (R), die (D), or stop wearing the mask while they are still infectious (I).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2818714&req=5

pone-0009018-g001: Schematic relationship between mask wearing individuals and non-mask wearing individuals for pandemic (H1N1) 2009.The arrows that connect the boxed groups represent the movement of individuals from one group to an adjacent one. Non-mask wearing susceptible individuals (S) can either become exposed (E) or susceptible wearing a mask . Non-mask wearing exposed individuals (E) can either become infectious non-mask wearing (I) or mask wearing exposed (). Non-mask wearing infectious individuals (I) can either recover (R), die (D), or become infectious wearing a mask (). Mask wearing susceptible individual () can either become an exposed mask wearer () or a non-mask wearing susceptible (S). Mask wearing exposed individuals () can either become an infectious mask wearer () or a non-mask wearing exposed individual (E). A mask wearing infectious individual () can either recover (R), die (D), or stop wearing the mask while they are still infectious (I).
Mentions: Following the approached developed in [15], the population is divided into two subgroups: a mask wearing group (subscript m) and a non-mask wearing group. People move back and forth between the mask and non-mask groups based on the number of individuals infected with pandemic (H1N1) 2009. Individuals in each activity group are characterized by their epidemiological status: susceptible, denoted by S and , exposed, denoted by E and (i.e., people who are infected but not yet fully contagious), and infectious individuals, I and . Definitions of the eight epidemiological classes are summarized in Table 1 and the transfers are shown diagrammatically in Figure 1. Because we are evaluating the effectiveness of masks in a single influenza period, we use a closed system with no migration in or out, and births and natural deaths are not included in the model.

Bottom Line: To estimate the parameter values used for the effectiveness of facemasks, we used available data from studies on N95 respirators and surgical facemasks.The results show that if N95 respirators are only 20% effective in reducing susceptibility and infectivity, only 10% of the population would have to wear them to reduce the number of influenza A (H1N1) cases by 20%.We can conclude from our model that, if worn properly, facemasks are an effective intervention strategy in reducing the spread of pandemic (H1N1) 2009.

View Article: PubMed Central - PubMed

Affiliation: Energy and Infrastructure Analysis Group, Decisions Applications Division, Los Alamos National Laboratory, Los Alamos, New Mexico, United States of America. samantha.tracht@gmail.com

ABSTRACT
On June 11, 2009, the World Health Organization declared the outbreak of novel influenza A (H1N1) a pandemic. With limited supplies of antivirals and vaccines, countries and individuals are looking at other ways to reduce the spread of pandemic (H1N1) 2009, particularly options that are cost effective and relatively easy to implement. Recent experiences with the 2003 SARS and 2009 H1N1 epidemics have shown that people are willing to wear facemasks to protect themselves against infection; however, little research has been done to quantify the impact of using facemasks in reducing the spread of disease. We construct and analyze a mathematical model for a population in which some people wear facemasks during the pandemic and quantify impact of these masks on the spread of influenza. To estimate the parameter values used for the effectiveness of facemasks, we used available data from studies on N95 respirators and surgical facemasks. The results show that if N95 respirators are only 20% effective in reducing susceptibility and infectivity, only 10% of the population would have to wear them to reduce the number of influenza A (H1N1) cases by 20%. We can conclude from our model that, if worn properly, facemasks are an effective intervention strategy in reducing the spread of pandemic (H1N1) 2009.

Show MeSH
Related in: MedlinePlus