The recent spread to mammals of H5N1 influenza - commonly known as bird flu - needs to be monitored, but the risk to humans remains low, the World Health Organization said on Wednesday. H5N1 has spread among poultry and wild birds for 25 years, Director-general Tedros Adhanom Ghebreyesus told reporters in a virtual briefing, but the recent reports of infections in mink, otters and sealions "need to be monitored closely". He said the risk to humans remains low, noting that human cases have been rare since the flu strain emerged in 1996. "But we cannot assume that will remain the case and we must prepare for any change in the status quo," Tedros said.