Influence of Population Immunosuppression and Past Vaccination on Smallpox Reemergence

• DOI: 10.3201/eid2404.171233
• Publication Date: 2018-02-26T14:22:56Z
• Authors: C. Raina MacIntyre; Valentina Costantino; Xin Chen; Eva Segelov; Abrar Ahmad Chughtai; Anthony Kelleher; Mohana Kunasekaran; John Michael Lane
• Keywords: Immunosuppression; Smallpox vaccine

We built a SEIR (susceptible, exposed, infected, recovered) model of smallpox transmission for New York, USA, and Sydney, South Wales, Australia, that accounted age-specific population immunosuppression residual vaccine immunity conducted sensitivity analyses to estimate the effect these parameters might have on reemergence. At least 19% York's 17% Sydney's are immunosuppressed. The highest infection rates were in persons 0-19 years age, but death those >45 age. Because low level immunity, was more influential than vaccination our model. Despite widespread until 1980 outbreak severity appeared worse York Sydney. Immunosuppression is highly prevalent should be considered future models because excluding this factor probably underestimates rates.