(SYDNEY, Saturday 15 June 2019) A deliberate release of smallpox in a big city is a nightmare public health scenario, but new research by the Kirby Institute at UNSW Sydney published today in PLOS One suggests that the worst can be avoided through comprehensive health system planning.
According to the research, a smallpox attack in Sydney could require up to 100% of hospital beds with an epidemic lasting up to 300 days, if the health system response is not planned, rapid and coordinated.
The researchers used mathematical modelling to predict the impact of a smallpox attack on Sydney’s health system. This is the first study globally to estimate health system requirements for smallpox deliberate release. Smallpox was eradicated in 1980 but has become a renewed security concern since a close relative of smallpox was created in a lab in 2017.
“It is essential to plan for health system surge capacity, both human resources and physical space requirements, in order to minimise the impact of potential bioterrorism attacks,” says Professor Raina MacIntyre, who is head of the Biosecurity Program at the Kirby Institute at UNSW Sydney. “Whilst we already do this very well, our research pinpoints specific bottlenecks which can result in severe epidemic. These include lack of physical space and staffing to isolate cases of smallpox, staff to track and vaccinate their contacts, resources to protect healthcare workers and the ability to act very quickly.”
Sydney has a robust health system in place, with the authors estimating a workforce of over 100,000 clinical health care workers and almost 15,000 hospital beds. However, the study found that with each day of delay in a coordinated response, the ability to isolate infected patients and to track and vaccinate their contacts becomes more difficult and can significantly influence the size of the epidemic. While a small attack could require 4% of all hospital beds (more than the requirements for seasonal flu) for smallpox patients, a large attack will require more hospital beds than are available, within just 40 days, with corresponding surge requirements for clinical health care workers. This will impact the ability to treat other, urgent conditions such as heart attacks, if no overflow beds are planned. Surge will also be required for the public health workforce and nurse immunisers to track and vaccinate contacts of infectious cases, which is essential for stopping ongoing transmission.
“While infectious disease outbreaks are inherently unpredictable, there are many factors we can control and mitigate, to ensure epidemics are stopped rapidly,” says Professor MacIntyre. “Ideally, we would want to see a high-level public health response kick in within a week of the first smallpox diagnosis. Our model shows that if 95% of patients are isolated as soon as they become symptomatic, outbreak control could be achieved within 100 days and severe impacts on the health system can be avoided.”
The research was funded through the NHMRC Centre for Research Excellence for Integrated Systems for Epidemic Responses, and builds on work conducted for the Office of Health Protection, Department of Health, Australia.