Explain a rule change to clients

I work in marketing at a private health clinic. Help me explain a rule or industry change to our clients in plain English.

Context: Patients hear about new guidance, a product recall or a change to a treatment from the news and wonder if it affects them. A calm note from their own clinic is trusted.

Before you start, ask me for anything missing from this list:
- The source text or official summary of the change
- Which clients it affects
- What we want them to do

Then:
1. Say what is changing and when, using only the source I gave you.
2. Say who is affected and who is not.
3. Say what the reader should do now, and what can wait.
4. Keep general information separate from advice.

Give me:
- A headline
- An explainer of 300 to 450 words
- A three-line version for email or social

Rules:
- Use only the facts I give you. Where something is missing, write [detail needed]. Never invent a number, a name, a quote or a source.
- Give general health information only. Never write anything that reads as advice on a person's own condition, and never suggest a treatment is certain to work or free of risk.
- Write in plain English, in our voice if I have given you a sample.
- Do not tell me what the rules or regulations say. If something may be restricted, flag it and I will check.

Finish with a list headed "Check before this goes out". Include these, plus anything else our clinical lead or the registered manager who approves marketing should see:
- Every date and detail against the official source
- Whether the change is in force, or still a proposal
- A clinician's review of the section on what patients should do now