A Level 5 alert signals that the pandemic has begun.

The World Health Organisation is planning to elevate its pandemic alert status to Level 4, the highest level since the alert system was put into place in 1999. A Level 4 alert is described as “containment of the new virus in a limited area or delay of its spread” but it is also an acknowledgement that the virus is contagious between humans. A Level 5 alert signals that the pandemic has begun.

If the World Health Organization does increase the pandemic alert to Level 4 this will have been implications for people who want to travel and the distribution of anti-viral medicines such as Tamiflu and Relenza from global stockpiles will begin. Scientists will also begin to work on producing a pandemic vaccine to prevent individuals from getting the virus in the first place. The decision whether to raise the pandemic level to Level 4 will be issued by the World Health Organisation Director General after consultation with various experts.

Anne Schuchat at the Centers for Disease Control said that the World Health Organisation was likely to issue travel recommendations and that there was a “strong possibility” that the alert level change would be announced today. Many countries are now screening passengers arriving in their countries for flu symptoms and in the European Union a warning has been issued advising travelers to stay away from areas which have experienced the swine flu virus.

At the moment the reality is that nobody is quite certain what the future holds because the full extent of the spread of the virus and exactly how contagious it is and how dangerous it is to humans has not been properly documented. The next few days will prove to be crucial as scientists and health organisations around the world attempt to gather more information about this outbreak.

According to the latest reports one case has even been confirmed closer to home in the European Union in Spain.

UPDATE: LEVEL 4 ALERT ANNOUNCED BY THE WORLD HEALTH ORGANISATION. BIRD FLU IN UK.