Direct contact and droplets are the primary ways influenza spreads. Under certain conditions, however, aerosol transmission is possible. In a study published in the current issue of Clinical Infectious Diseases, available online, the authors examined such an outbreak in their own hospital in Hong Kong.

The H1N1 pandemic influenza provided several important lessons that may help in preparing for future influenza outbreaks, write Drs. Donald Low and Allison McGeer in an analysis in CMAJ (Canadian Medical Association Journal).

A US study of flu cases in adults and children living in Wisconsin concluded that the risk of serious complications from 2009 H1N1 swine flu was no higher than the risk of serious complications from recent seasonal flu strains.

You can read about the study in the 8 September issue of the Journal of the American Medical Association, JAMA.

By autumn 2009, almost half of the population of Norway had been vaccinated against the pandemic influenza A (H1N1) virus. Many had also been infected by the virus during the summer and autumn outbreaks. The majority of those who were vaccinated or were infected are expected to have developed immunity to the virus. A study of the Norwegian population's immune status to the pandemic virus in January 2010 was recently published in the journal Eurosurveillance.

The World Health Organization (WHO) announced today that the 2009 H1N1 pandemic has effectively ended, and the world has moved into a "post-pandemic" phase characterized by traditional seasonal patterns of influenza.

"The new H1N1 virus has largely run its course," WHO Director-General Dr. Margaret Chan said in a telephone news conference. "During the pandemic, H1N1 crowded out other influenza viruses to become the dominant circulating virus. This is no longer the case."

Secretary of State Hillary Rodham Clinton arrived in Vietnam on Thursday to participate in the Association of Southeast Asian Nations (ASEAN) regional forum and to mark the 15th anniversary of the normalization of diplomatic relations between the U.S. and Vietnam, VOV News reports. According to the news service, this is Clinton's first visit to the country since she became secretary of state. During her trip, she will have meetings with Deputy Minister and Foreign Minister Pham Gia Khiem (7/22).

Advertising and media coverage about swine flu reduced public concern and improved the uptake of useful, protective behaviours such as hand-washing, according to new research led by Professor Susan Michie at UCL.

The research, funded by the Department of Health's National Institute for Health Research, is published today in the journal Health Technology Assessment.

The data back up the government's policy of prioritising pregnant women, the under 5s, and those with long term respiratory problems for vaccination against swine flu.

A panel at the 2010 Aspen Ideas Festival on Thursday addressed how the world can better prepare for the next global pandemic.

Reggie Van Lee, an executive vice president with Booz Allen Hamilton, who leads the firm's public health and not-for-profit businesses, moderated the discussion with ABC News' senior health and medical editor Richard Besser; Nigel Crisp, an independent crossbench member of the U.K. Parliament's House of Lords and former head of Britain's National Health Service; and Nathan Wolfe, director of the Global Viral Forecasting Initiative and a visiting professor in human biology at Stanford.