WASHINGTON, July 2 (Reuters) - The new H1N1 influenza strain may be just a little less catching than seasonal flu, but seems a little better able to cause stomach upsets, researchers reported on Thursday.

Researchers in the Netherlands, meanwhile, found it lives very well in the nose and their findings suggest it has the ability to stay around for a long time -- and get worse.

Although flu season usually ends in April in the Northern Hemisphere, the new virus is still causing widespread illness and it is actively in the mix of seasonal flu viruses now circulating during the Southern Hemisphere's winter.

He said health officials should keep an eye out for it, as the change may signal the virus is gaining the ability to spread more quickly and easily than it already does. Researchers are also watching for signs the virus has developed mutations that allow it to resist antiviral drugs -- and have found two instances so far, one in Japan and one in Denmark.