Four patients hospitalized in North Carolina with severely compromised immune systems had H1N1 flu viruses resistant to the antiviral drug oseltamivir, the World Health Organization reported this week. The cases occurred between mid-October and early November in a single hospital unit. Around the same time, oseltamivir-resistant H1N1 flu was detected in eight patients with severely compromised immune systems in a hospital unit in Wales, UK. The number of oseltamivir-resistant H1N1 cases rose by 68% in the past two weeks, to 96, but do not appear to suggest a public health threat, WHO said. About one-third of the patients have had severely suppressed immune systems due to cancer, chemotherapy or post-transplant treatment. In other flu-related news, the CDC today reported 82 adverse event reports per 1 million H1N1 vaccine doses distributed, compared with 47 reports for seasonal flu vaccine. No substantial differences were noted in the serious adverse events reported for the two vaccine types.