See 'About Health sharing' section in:
Share and view health data in the Health app - Apple Support
If a friend or family member chooses to share their health data with you, you can also receive notifications when there are changes to their health data.
Also see:
Health app data Share with Provider FAQ - Apple Support
which may also apply.
Q: How frequently is the data updated?
A: After a user elects to share portions of their Health app data with a participating organization, any new data collected in the Health app is automatically uploaded to Apple’s Health Sharing Cloud approximately once every 24 hours, depending on factors such as whether the user’s iPhone is connected to the internet.