In opening the World Health Organization's executive board meeting this week, the head of the body cited anti-vaccine sentiments as a worrisome trend that may be very difficult to change. Noting that some countries are continuing to see severe cases of 2009 H1N1 infection in relatively young people, WHO Director-General Margaret Chan said, "In some cases, persuading the public to seek vaccination has become even more problematic than during the pandemic. As documented in the report on immunization, the problem of public mistrust extends well beyond influenza vaccines." News