In the past, new strains have generated pandemics causing high death rates and major disruptions to society. Although healthcare has improved in recent decades, epidemiological models project that today a pandemic is likely to result in 2 to 7.4 million deaths globally. In developed countries alone, accounting for 15% of the world’s population, models project […]

Origin of H1N1 (‘Mexican’ or ‘Swine’ flu)

The accompanying graph reveals the origin of the ‘Swine flu virus’ as deduced from sequence analysis of the respective genome segments, that through a process of so-called “re-assortment” shaped the new virus. All the eight segments originate from avian influenza A viruses that were introduced into pigs directly from birds or through a human intermediate […]


Classical vaccines against different highly pathogenic avian influenza viruses for use in domestic poultry and other birds have been developed successfully. These are adjuvanted vaccines that provide adequate and broad protection against disease caused by HPAI virus strains. Vaccination of poultry and other domestic or zoo birds may also prevent or reduce human exposure to […]


Continuous global surveillance of influenza is key. The World Health Organization (WHO) has a network of 112 National Influenza Centres that monitor influenza activity and isolate avian influenza viruses across all continents. National Influenza Centres report the emergence of an unusual influenza virus immediately to the WHO Global Influenza Programme or to one of the […]

How to prevent avian influenza

Travellers, especially those going to high-risk zones such as Southeast Asia, should follow the guidelines below in order to avoid contracting avian influenza: Avoid any close contact with domesticated birds. Prevent bird flu contact by avoiding rural areas, small farms or open-air markets. Avoid any close contact with domesticated birds. Prevent bird flu contact by […]

What can healthcare workers do?

Get vaccinated! Influenza vaccination is the best way to reduce chances of getting ill from influenza and from giving influenza to patients, co-workers and family. Indications are that vaccination against seasonal influenza at least partially protects against possible pandemic influenza strains. Also consider this: if one third of the population receives its annual shot with […]

Pandemic alert phases

The World Health Organization (WHO) has developed an alert system to help inform the world about the development of the different stages towards a pandemic. The alert system is comprised of six phases. The current situation with the HPAI-H5N1 virus in animals and humans places the world in pandemic alert phase 3. This means that […]

Pandemic preparedness planning

Detailed planning is essential to ensure a coordinated response to an influenza pandemic, both at the national and international levels. Should schools be closed to prevent influenza from spreading? What about hospital capacity in case of a severe pandemic? How can we track the pandemic virus as it spreads? How and to whom will the […]

Vaccination during a pandemic

Since it is impossible to vaccinate the entire world population against a pandemic influenza virus when a pandemic emerges, it is necessary to determine which groups must be immunized with priority. After all, effective allocation of vaccines will play a critical role in slowing down the spread of the influenza pandemic and reducing its effects […]

Pandemics in the 20th century

When a new influenza virus appears, against which the human population has no immunity, a pandemic may occur. This happened in 1918 (the “Spanish flu”, caused by an H1N1 subtype), in 1957 (the “Asian flu” caused by an H2N2 subtype) and in 1968 (the “Hong Kong flu”, caused by an H3N2 subtype). Of all pandemics, […]