Swine flu now becomes a pandemic, meaning what?

The swine flu (H1N1) viral infection initially emerged in Mexico in April 2009. In early June, the rising figures indicated ~30,000 cases and ~141 related-deaths in 74 countries worldwide. World Health Organization (WHO) director Dr. Margaret Chan declared it as level 6 "pandemic". So should we be worried? According WHO's definition in 2005, a pandemic has to meet three general conditions:

A. The virus infects and causes serious illness in humans.
B. Humans do not have immunity against the virus.
C. The virus spreads easily from person-to-person and survives within humans.

Furthermore, the specific scaling of pandemic is as follows:

Phase 1: Viruses are circulating naturally among domestic and/or wild animals, but it does not have the capacity to infect humans.
Phase 2: During this pandemic phase, viruses are circulating naturally among domestic and/or wild animals AND a few humans are infected from contact with sick animals. No evidence of person to person transmission.
Phase 3: A pandemic alert. the recombination or re-assortment of genes has caused sporadic human cases or infection in small clusters. There is some but limited transmission from person to person.
Phase 4: At this pandemic phase, there is definitely transmission from person to person. Localized communities are affected. A country experiencing this level of activity is supposed to contact the WHO for collaborative investigation and management. This is certainly a large step toward a pandemic. At this point, there is an effort to contain the disease. It does not necessarily mean that a pandemic is imminent.
Phase 5: A phase one step away from a full scale pandemic. This is characterized with rapid transmission of the virus among humans and at least 2 countries in a region are affected. This indicates a pandemic is imminent. All kinds of government programs go into action at this point. Hospitals begin to mobilize. Institutions implement their pandemic plans.
Phase 6: A full scale pandemic. This occurs when the criteria in Phase 5 are met and at least one other country is now affected. There is sustained human to human transmission. In previous pandemics, like the Spanish Flu of 1918, millions lost their lives during this pandemic stage.

It is clear that the criteria address only the geographic spread and the rapidness of between human transmission. Nothing on disease severity. Fortunately, the current swine flu seems to be moderate and causing only mild illness in most patients. "Moving to pandemic Phase 6 does not imply we will see increased deaths or serious cases," said Dr Chan. She also noted that a right balance between complacency and vigilance was essential as pandemic strategies would vary between countries depending on many specific factors. One major concern is that now the swine flu is migrating from northern to southern hemisphere, there may be a chance for the virus to mutate and become more virulent. A take home message? No need to be excessively concerned and stressed out as of now, but do keep a healthy dose of mental alertness regarding the progression of this virus.