The current swine flu epidemic is affecting younger people and is more unusual than past seasonal flues, public health professors said. School of Public Health professors Davidson Hamer, Jean van Seventer and David Ozonoff discussed the epidemiology of the current H1N1 pandemic as well as its unique biology to an audience of about 50 at a Public Health Forum at the Boston University School of Medicine on Wednesday.’ ‘In contrast to most seasonal epidemics, this is hitting a younger age group overall,’ Hamer said. ‘The elderly are much less affected and less likely to be hospitalized.’ There have been relatively few cases of swine flu at nursing homes, where there are usually major influenza outbreaks, Hamer said. In addition, Ozonoff said, the patterns show that many cases of the current swine flu were reported prior to the official start of the season on Oct. 4. ‘There is a left age shift of the pandemic strain because only about two percent have been above 60 years old,’ he said. ‘The influenza is amazingly unpredictable and patchy in space and time.’ Van Seventer said H1N1 has a very rapid mutation rate.’ ‘ ‘The current swine flu is a quadruple re-assortment of an influenza virus that includes two swine, one avian, and one human, making it highly contagious,’ she said. Ozonoff emphasized the number of aspects about swine flu that scientists and the public still do not know about. ‘ ‘We don’t know why flu is seasonal, what makes flu virulent, what the dynamics of transmission are or what determines host susceptibility and specificity,’ he said. Ozonoff said it is important for health care practitioners to get the most recent vaccinations available. ‘If you can avoid contracting the disease by receiving the vaccine, you won’t be able to risk affecting other people,’ he said. Hamer agreed but said the availability of the vaccine should be limited to people who are more likely to catch the virus. ‘One of the issues is if there is going to be enough vaccine,’ he said. ‘I would suggest limiting it to younger and high risk patients.’ Although scientists do not know exactly how the virus is transmitted from person to person, there are three possible ways it can happen, Ozonoff said. ‘We don’t know the main mode of transmission from person to person,’ he said. ‘But it can either be by droplet, airborne, or fomites [materials that are likely to carry infection].’ ‘Some ways to avoid illness are good personal hygiene, respiratory etiquette, and routine cleaning of surfaces,’ Hamer said. Van Seventer said swine flu is classified as a pandemic because it has reached global levels. ‘For pandemic to exist, a new virus needs to emerge, it needs to be able to replicate and cause disease, and be readily transmissible between humans,’ she said. Kristen Smith, an environmental health graduate student pursuing a doctorate, said she was surprised to hear some of the information at the forum. ‘Although I knew most of the information discussed, it was helpful to hear Ozonoff discuss epidemiology,’ she said. ‘It is surprising that younger people are being affected.’