this might help:
<b><u>I have already lodged my Australian visa application</u></b>
You will be advised by email or by your case officer what health examinations you need to do (if any). You will then be requested to complete these examinations within a certain time period. Please wait until your visa case officer contacts you, do not use the My Health Declarations service if you have already lodged a visa application. It will delay processing of your visa application.
Note: To minimise processing delays, you should complete your required health examinations as soon as possible after your case officer has advised you to do so.