In case of a medical emergency you can call 991 for an ambulance or +260 977 770302 for an SES ambulance. In extreme cases where you may need to be evacuated to South Africa you should liaise with your medical insurance provider and SES so that they can discuss the logistics with each other. SES manage the ground handling such as liasing with the airport, the medivac aircraft and ambulance transfers. Whilst SES will charge for their services if you are not insured with them, your own insurance provider should pick up the bill provided you are covered.
SES provide emergency evacuation handling on the ground as well as a general practitioners service and paramedic service. They also provide medical insurance, mainly to residents and operators in the region. If you have any bangs and scrapes or are feeling under the weather, SES can help. If it is something more serious then you should give them a call and ask for their advice.