Hello, thanks for your question today! I am Dr. Drew, and I am a licensed veterinarian. I'll be happy to help you in any way I can.
Much like flu vaccine for people,
the kennel cough vaccine for dogs doesn't always provide 100% immunity,
so the fact that Molly had been vaccinated, doesn't mean she can't develop kennel cough, or other upper respiratory infections.
As you've suspected, puppy school is a place where many puppies come in contact with various viral or bacterial infections,
fortunately, however, as long as Molly is active, and eating and drinking well, there is probably not much need for worry,
but if she begins to become lethargic, or loses interest in food / water, or has nasal discharge or runny eyes, then medication may be necessary,
so I'd have to suggest a veterinary examination at that point.
If this is a viral infection, supportive care is the treatment - antibiotics are not effective against viruses.
Therefore, in many cases it's just a matter of letting the immune system do its job.
Thank you for your answer regarding Molly. Will the symtoms subside? she is still eating and drinking does eat alot of rubbish in the garden. Also is it ok to walk her? Should i inform the puppy school before going back next week?
Yes, the puppy school needs to be informed,
so that they can decide whether or not they wish to permit Molly to return prior to being cleared by a veterinarian.
As long as she continues to eat and drink well, and is active, it is likely that she'll get better without veterinary attention,
but if more than 7 days passes with no improvement, or if she stops eating, you'll need to seek veterinary care.