You must minimise the risk of infection from the outset when dealing with any incident. This applies to you, the casualty, and any bystanders. Similarly, when the casualty has been treated it is vital that all soiled dressings etc, are disposed of correctly.
Rescuers should take appropriate safety precautions where feasible, especially if the casualty is known to have a serious infection such as tuberculosis (TB), severe acute respiratory distress syndrome (SARS) or coronavirus (COVID-19).