- The cost of HAI patients using beds for several additional days is likely to have an opportunity cost greater than the cost of the bed. Indeed, when patients need to be isolated due to AMR, there may be several unoccupied beds in a ward, thus preventing other patients from receiving the care they need.

- It is possible that HAIs are contracted during outpatient care, which are presumed to be community acquired infections upon hospital admission, underestimating incidence of HAI.

- Adherence to HAI treatment protocols that assume all HAIs are AMR, which could result in lower cost due to more effective treatment or higher cost due to use of more costly second- and third-line drugs in all HAI cases.

- HAI rates and related costs of treating healthcare workers and the costs associated with the loss of capacity while they recover. Furthermore, there is a loss in job satisfaction for healthcare workers working in difficult, dirty conditions, and a risk of absenteeism. In the longer-term, they may decide to change job or even change career.

- Health systems operating at or above their current capacity, with bed occupancy at or above 100%, may be required to turn away prospective inpatients. Hospital admissions would presumably be higher if the health system had higher capacity, which could lead to higher rates of HAIs, or lower in case of less overcrowding.

- Patients (and their social circle) not returning to a healthcare facility due to a previous experience– resulting either in delayed treatment seeking and future worse health outcome, and/or seeking care at a more distant or higher-level health facility, resulting in higher costs.

- The likelihood that future health emergencies or pandemics will be more difficult to prevent and control without adequate investment in WASH, HCWM and environmental cleaning.

- Psychological impacts of being infected with an HAI, especially one that is AMR, and patient dissatisfaction associated with poor quality care and lack of WASH facilities.<sup>18</sup>

- Dissatisfaction of healthcare workers affecting their motivation to work, their treatment of patients, and career choices, which subsequently could affect health outcomes (see Annex 3 for a brief review of quality of care as it pertains to WASH).

This study relied on secondary data sources, including national statistics and published literature. Due to lack of data on costs and HAI rates for some countries, these were extrapolated from countries where data were available, and therefore may not reflect that country’s situation. In general, the HAI rates used were reflective of national contexts across SSA, and some countries had sufficient studies presenting HAI rates to make tailored estimates for those countries.

The study assumes that 50% of HAIs are AMR, which likely varies significantly within and across countries, and simplifies the many complexities associated with AMR. However, for the purposes of this analysis an AMR rate of 50% (based on Murray et al (2022)) may be quite conservative, and a more fine-tuned value would need to be used in future national studies based on localized rates and types of infection and resistance levels.

Only a few studies were available from SSA which estimated the direct medical costs of treating HAIs. Hence, estimates drawn from the more representative and better quality studies were extrapolated to other countries. The evidence shows that the costs associated with treating HAIs are highly dependent on the level of the healthcare facility, due to the better availability of diagnostics and more common use of third-line or patented drugs, more 18