No, they haven't yet
I listened to gardeners question time on the bbc I player yesterday, it was from FERA the Defra research lab, they are working on it and are asking for gardeners help, it appears some strains of the downy mildew are resistant to any treatment.
(the programme is still on if you wish to listen or go to the GQT website)

Even before the recent problems I never rated Impatiens.

Pelargoniums flower for longer are much tougher and are much more drought resistant.

I like Impatiens because they flower so well in shade but after losing them all a few years ago I now use bedding begonias which don't have any problems and love shade. Wish I could grow Pelargoniums but they don't flower well in shade.

If you really want impatiens go for the New Guinea hybrids. Jaykaty, I love the begonias too - completely reliable whtever the weather!

With all the cold and rain last year the new guinea ones were poor here. I did have success with osteospermum and have just bought some small plants from a local nursery ....£1.85 instead of £5.99......
Last years two survived the winter in a cold gh and are doing so well I pruned them back and fed them.

Thanks for all your answers