If ever you needed evidence of the importance of celebrity in health awareness campaigning then look no further.

A paper in the Journal of the American Medical Association Internal Medicine reports that the actor, Charlie Sheen’s, disclosure last November that he is HIV positive resulted in a 265% increase in news reports mentioning HIV and 6500 news stories on Google alone.

The so called ‘Charlie Sheen effect’ received a further buff-up yesterday when the paper was published.  When I looked this afternoon Google was already listing over 500 news stories including this one from the BBC.

I suspect the impressive figures quoted above (and more) are being copied and pasted into health PR consultancy presentations as we speak.  To be sprung upon the prospective client as a presage to persuading them to part with their money for that well-known health awareness game of ‘Find a Celebrity.’

The aim in mind? That most intoxicating thing in PR circles – celebrity endorsement.

What they won’t tell you of course is that: just as not all celebrities are to our liking, so their association with a health issue is as likely to be a lead balloon as have a halo effect.  And it’s not always the celebrity’s fault.  Often their lack of impact is simply because the overall health campaign is not good enough whether in terms of message, timing or promotion.

On the other hand some celebrities may simply be not worth the trouble.

I remember working on one health campaign many moons ago when I was assigned to go and pick up a well-known model and take her to a photo-shoot.  Me and the taxi driver duly turned up at her house.  After several knocks on the door she appeared on the doorstep in her dressing gown.  We were promptly sent away for an hour while she got ready.  The tax driver went to get another fare. I went to the pub.

Eventually,  the model, her young son (who couldn’t be left at home), the taxi driver (the same one who came back, thank goodness) and me, made our way across London in the back of a cab in the afternoon sun in complete silence.  Naturally, once at the studio and as soon as the camera was upon her, she came alive.

But somehow her mood towards me didn’t seem to change much whatever I tried.  I remained that rather unattractive sweaty flunky that had been following her around.  The feeling was mutual I can assure you.  In fact, I can’t quite convey the relief I felt when I dropped her and her son back home early that evening – a £100 lighter in taxi fares I might add.

What sets Charlie Sheen’s public statement apart from the sort of celebrity endorsement I have described above – and the same can be said for that matter about Jade Goody’s incredibly moving and ultimately tragic public story of living with cancer or Terry Pratchett’s outspoken campaigning for people with dementia until his dying da- – can be summed up in one word: authenticity.  It is the sense of unprompted, unvarnished truth being told for good reasons and without ulterior motives which resonates with the public and gets them on side.

This is the sort of celebrity involvement that can change behaviours rather than simply adding to column inches is what we want to see.  We saw it with Jade Goody and women presenting themselves for cervical screening.  Also with cricketer Shane Warne and smoking cessation in Australia (which proved the ‘no publicity is bad publicity’ adage).

But what we often forget is that the ‘high maintenance’ feature of this sort of work doesn’t come in the form of massaging celebrity egos.  It actually manifests itself in the nitty gritty work needed to make sure those who hear these celebrity stories have somewhere to go to for advice and help.  And for months and years afterwards.

As the authors of the JAMA said yesterday, it is perhaps too early to assess the full ‘Sheen effect’ yet.  But when such media events do happen we should all stand ready to capitalise on them and ensure they do.