According to the WHO, the following are the “Ten things you need to know about pandemic influenza”

1. Pandemic influenza is different from Influenza A(H5N1).

Avian influenza refers to a large group of different influenza viruses that primarily affect birds. On rare occasions, these bird viruses can infect other species, including pigs and humans. The vast majority of avian influenza viruses do not infect humans. An influenza pandemic happens when a new subtype emerges that has not previously circulated in humans.

For this reason, avian H5N1 is a strain with pandemic potential, since it might ultimately adapt into a strain that is contagious among humans. Once this adaptation occurs, it will no longer be a bird virus--it will be a human influenza virus. Influenza pandemics are caused by new influenza viruses that have adapted to humans.

2. Influenza pandemics are recurring events.

An influenza pandemic is a rare but recurrent event. Three pandemics occurred in the previous century: “Spanish influenza” in 1918, “Asian influenza” in 1957, and “Hong Kong influenza” in 1968. The 1918 pandemic killed an estimated 40–50 million people worldwide. That pandemic, which was exceptional, is considered one of the deadliest disease events in human history. Subsequent pandemics were much milder, with an estimated 2 million deaths in 1957 and 1 million deaths in 1968.

A pandemic occurs when a new influenza virus emerges and starts spreading as easily as normal influenza – by coughing and sneezing. Because the virus is new, the human immune system will have no pre-existing immunity. This makes it likely that people who contract pandemic influenza will experience more serious disease than that caused by normal influenza.

3. The world may be on the brink of another pandemic.

Health experts have been monitoring a new and extremely severe influenza virus – the H5N1 strain – for almost eight years. The H5N1 strain first infected humans in Hong Kong in 1997, causing 18 cases, including six deaths. Since mid-2003, this virus has caused the largest and most severe outbreaks in poultry on record. In December 2003, infections in people exposed to sick birds were identified.

Since then, over 100 human cases have been laboratory confirmed in four Asian countries (Cambodia, Indonesia, Thailand, and Viet Nam), and more than half of these people have died. Most cases have occurred in previously healthy children and young adults. Fortunately, the virus does not jump easily from birds to humans or spread readily and sustainably among humans. Should H5N1 evolve to a form as contagious as normal influenza, a pandemic could begin.

4. All countries will be affected.

Once a fully contagious virus emerges, its global spread is considered inevitable. Countries might, through measures such as border closures and travel restrictions, delay arrival of the virus, but cannot stop it. The pandemics of the previous century encircled the globe in 6 to 9 months, even when most international travel was by ship. Given the speed and volume of international air travel today, the virus could spread more rapidly, possibly reaching all continents in less than 3 months.

5. Widespread illness will occur.

Because most people will have no immunity to the pandemic virus, infection and illness rates are expected to be higher than during seasonal epidemics of normal influenza. Current projections for the next pandemic estimate that a substantial percentage of the world’s population will require some form of medical care. Few countries have the staff, facilities, equipment, and hospital beds needed to cope with large numbers of people who suddenly fall ill.

6. Medical supplies will be inadequate.

Supplies of vaccines and antiviral drugs – the two most important medical interventions for reducing illness and deaths during a pandemic – will be inadequate in all countries at the start of a pandemic and for many months thereafter. Inadequate supplies of vaccines are of particular concern, as vaccines are considered the first line of defence for protecting populations. On present trends, many developing countries will have no access to vaccines throughout the duration of a pandemic.

7. Large numbers of deaths will occur.

Historically, the number of deaths during a pandemic has varied greatly. Death rates are largely determined by four factors: the number of people who become infected, the virulence of the virus, the underlying characteristics and vulnerability of affected populations, and the effectiveness of preventive measures. Accurate predictions of mortality cannot be made before the pandemic virus emerges and begins to spread. All estimates of the number of deaths are purely speculative.

WHO has used a relatively conservative estimate – from 2 million to 7.4 million deaths – because it provides a useful and plausible planning target. This estimate is based on the comparatively mild 1957 pandemic. Estimates based on a more virulent virus, closer to the one seen in 1918, have been made and are much higher. However, the 1918 pandemic was considered exceptional.

8. Economic and social disruption will be great.

High rates of illness and worker absenteeism are expected, and these will contribute to social and economic disruption. Past pandemics have spread globally in two and sometimes three waves. Not all parts of the world or of a single country are expected to be severely affected at the same time. Social and economic disruptions could be temporary, but may be amplified in today’s closely interrelated and interdependent systems of trade and commerce. Social disruption may be greatest when rates of absenteeism impair essential services, such as power, transportation, and communications.

9. Every country must be prepared.

WHO has issued a series of recommended strategic actions for responding to the influenza pandemic threat. The actions are designed to provide different layers of defence that reflect the complexity of the evolving situation. Recommended actions are different for the present phase of pandemic alert, the emergence of a pandemic virus, and the declaration of a pandemic and its subsequent international spread.

10. WHO will alert the world when the pandemic threat increases.

WHO works closely with ministries of health and various public health organizations to support countries' surveillance of circulating influenza strains. A sensitive surveillance system that can detect emerging influenza strains is essential for the rapid detection of a pandemic virus.

Six distinct phases have been defined to facilitate pandemic preparedness planning, with roles defined for governments, industry, and WHO. The present situation is categorized as phase 3: a virus new to humans is causing infections, but does not spread easily from one person to another.

WHO Advice to Travellers to Avoid Infection[3]

The WHO offers the following recommendations to travellers coming from and going to countries experiencing outbreaks of highly pathogenic H5N1 avian influenza [4]

• WHO advises travellers to avoid contact with high-risk environments in affected countries
• Travellers to areas affected by avian influenza in birds are not considered to be at elevated risk of infection unless direct and un-protected exposure to infected birds (including feathers, faeces and under-cooked meat and egg products) occurs.
• WHO continues to recommend that travellers to affected areas should avoid contact with live animal markets and poultry farms, and any free-ranging or caged poultry. Large amounts of the virus are known to be excreted in the droppings from infected birds. Populations in affected countries are advised to avoid contact with dead migratory birds or wild birds showing signs of disease.
• Direct contact with infected poultry, or surfaces and objects contaminated by their droppings, is considered the main route of human infection. Exposure risk is considered highest during slaughter, defeathering, butchering, and preparation of poultry for cooking. There is no evidence that properly cooked poultry or poultry products can be a source of infection.
• Travellers should contact their local health providers or national health authorities for supplementary information.

How to Prepare: Practical Considerations for Travellers[5]

Health professionals are concerned that the continued spread of a highly pathogenic avian influenza virus among animals (mainly poultry) in Asia, Africa, the Middle East and Europe has the potential to significantly threaten human health.  If highly pathogenic avian influenza, such as the H5N1 subtype, mutates and spreads easily from one person to another, influenza could break out globally, and lead to a pandemic.  While there are no reports of sustained human-to-human transmission of such a virus, international health agencies are advising those travelling overseas on how to prepare for a pandemic, should one strike.  

Travellers should be aware that it may not be possible to travel during an outbreak.  Governments may close borders suddenly and without advance warning; commercial air, land and sea carriers could curtail or cancel service; and restricting travel may be the best way to reduce the risk of exposure to the virus. These developments could impede a return to the United States or travel to another country or region.  Therefore, travellers who are overseas during a pandemic may need to remain where they are until conditions improve, a situation which could last several months.  

Short-Term Visitors, Tourists, and Students Abroad

Consult with your doctor before you travel and ask about medications you should take with you.  Research the availability and quality of medical facilities at your destination.  Be aware that hotels may cease to provide housekeeping and food services during a pandemic. Consider changing your travel plans or returning to your country once there is evidence of sustained human-to-human transmission, since commercial air transport may become unavailable at an early point and as health services in the destination might experience a shortfall in capacity.

Plan to Remain in Country

 If the WHO declares a pandemic, travellers who are overseas should be prepared to remain in country for an extended period.  You should avoid non-essential travel beyond your home and workplace and you should limit activities that could expose you to others who may be ill.  Based on varying conditions abroad, you should prepare contingency plans and emergency supplies (non-perishable food, potable water or water-purification supplies, medication, etc.) for the possibility of remaining in country for at least two and up to twelve weeks. 

Visit www.pandemicflu.gov to see examples of comprehensive planning checklists for individuals, businesses, schools, and other groups. 

What Can You Do?

You should wash your hands regularly with soap and warm water for at least 20 seconds to eradicate viruses and bacteria. When soap and water are not available, apply a hand sanitizer with a minimum of 60 percent alcohol content. Cover your coughs and sneezes. Get vaccinated against seasonal flu. Ask your employer, organization or school about pandemic contingency plans. And please review detailed community mitigation guidelines as well as information on the use of masks and anti-viral medications in a pandemic, also available on www.pandemicflu.gov .

What About During a Pandemic? During a pandemic, people should practice social distancing measures such as teleworking, limiting face-to-face meetings, avoiding crowds, and maintaining a distance of six (6) feet or more from other people.

Healthy employees should consult with their employer about reporting to work during a pandemic, taking into account local conditions and the risk of infection. Sick people, or those who reside with a sick person, should consult with their healthcare provider to determine the appropriate course of action which could include home treatment.

Keep Informed

Those living in or travelling to countries with human or animal cases of highly pathogenic avian influenza should consider the potential risks and plan accordingly. Keep current with the latest medical guidance and practical information. Visit the WHO site to review the latest situation updates and additional information on pandemic influenza.