This paper, published in the New England Journal of Medicine, examines how the Internet can help monitor, prevent and control emerging diseases. The authors argue that the emergence of influenza A(H1N1), or 'swine flu', in April 2009 shows the value web-based information holds for early disease monitoring.

Informal internet channels such as blogs, chat rooms and search engine request analyses can help identify outbreaks more quickly, prevent governments suppressing information and facilitate public health responses. Google and Yahoo data searches can be used to generate epidemic curves that show the number of new infections plotted against time, and are comparable to those derived from traditional influenza surveillance methods.

The Internet also connects experts — through wikis and social networks — to quickly disseminate reports and responses. There is also great potential from public information.

The authors give examples of approaches being taken to monitor infectious diseases, including swine flu, and highlight some of the online resources available, including Google Flu Trends, HealthMap and ProMED.

This article, written by the WHO Rapid Pandemic Assessment Collaboration and published in the journal Science, examines the spread of A(H1N1) influenza, or 'swine flu', and assesses its potential to cause a pandemic.

Analysing surveillance data from Mexico, the authors suggest the geographical spread of swine flu will likely be comparable to other twentieth century pandemics, although the associated impact on human health is difficult to predict.

The authors suggest that the outbreak originated in mid-February 2009 in the village of La Gloria, Veracruz, where over half the population suffered acute respiratory illness. They calculate that the virus transmissibility — the number of cases that one case generates on average — is between 1.4 and 1.6, similar to the transmissibility of previous flu viruses including those that led to the 1918, 1957 and 1968 pandemics. The authors estimate that by 30 April 2009, 6,000–32,000 people will have been infected, with 0.4–1.4 per cent of cases being fatal.

This article, published by the WHO, answers frequently asked questions about the A(H1N1) influenza virus, or 'swine flu'. It provides information on the availability, production and effectiveness of A(H1N1) vaccines.

The WHO says that no effective A(H1N1) vaccines are currently available (May 2009) but adds that work is underway to develop one. The Centers for Disease Control and Prevention in the United States, for example, has identified and prepared candidate vaccine strains and is distributing them to all interested parties on request.

A vaccine could be available in five to six months after a pandemic strain has been identified but the WHO notes that more than 90 per cent of the global capacity for vaccine production lies in Europe or the United States — which may have implications for vaccinating people in developing countries. While these countries are well-versed in distributing vaccines through mass campaigns, they may face difficulties in ensuring timely access to enough supplies of vaccine.

This article, published by the WHO, assesses the potential for a global pandemic of A(H1N1) influenza, or 'swine flu'. The authors outline the properties of influenza viruses that are needed to create a pandemic and discuss population vulnerability and pandemic severity. They highlight the populations at most risk, for example people with underlying conditions such as cardiovascular disease, and the role that nutritional status and the quality of health services can play in influencing a pandemic's severity.

In assessing the 2009 swine flu outbreak, they draw attention to the fact that mutations often occur in influenza viruses, which means that while the emerging virus may be mild, it could return in several months in a much more lethal form.

The authors say that A(H1N1) is a new influenza virus not previously seen in humans or animals. They suggest that it is more contagious than seasonal flu, but note that outside Mexico where the outbreak began, the virus is causing very mild illness in otherwise healthy people. They emphasise the risk to people suffering from other chronic diseases and note that the WHO estimates that 85 per cent of these people are in developing countries.

This timeline, published by Nature, lists key dates and events in the 2009 outbreak of A(H1N1) influenza, or 'swine flu'. Drawing on information from the WHO, the US Centers for Disease Control and Prevention and others, it details confirmed and reported cases of A(H1N1), highlights the geographical spread of the virus and links to official documentation and key research findings as they are released.

This feature, published by The Lancet, discusses the world's capacity to cope with a A(H1N1) influenza, or 'swine flu', pandemic. The author outlines some of the progress made in pandemic preparedness since severe acute respiratory syndrome (SARS) and H5N1 influenza (bird flu) hit the world a few years ago, but points out that many countries' plans are flawed.

Many countries in the Asia–Pacific focus on early containment of disease and "social distancing", a strategy particularly important for developing countries as many lack access to antiviral drugs and vaccines. But, on the other hand, countries that focus on surveillance end up with problems if the virus becomes pandemic.

Scientists are struggling to predict what the likely health impact of a pandemic will be because influenza viruses can become more dangerous as they mutate. And epidemiologists are trying to assess which groups of people are most vulnerable and why some people have more severe symptoms than others.

This fact sheet from the WHO outlines the basics about swine influenza, or "swine flu", including what it is, what its implications are for human health and how people become infected.

To protect yourself from swine flu, the WHO recommends avoiding contact with sick pigs or people, washing your hands regularly, practicing good health habits and following advice from local health authorities.