Hotel blocks and invitations

If it is in your budget, I would order info cards and mail them out to each of your guests. You can get them rather inexpensively on Zazzle, or similar sites. That’s probably going to be the easiest method for you, especially since you already have everybody’s mailing address. If that’s not within your budget, you are probably going to have to reach out to each guest/household individually; either by phone, email, or social media message.

I'd just do a separate mailing or email. You can supplement by giving a heads up when talking to people individually or by texting them. Not everyone does STDs. I've received this kind of communication evenly split between email and regular. You don't even have to order special cards unless you want to, you can just print the info on paper and mail it.

Spread the information by word of mouth. Tell parents and wedding party and they relax the information to the rest of your guests.