Is this a Pandemic or not?

The short answer is yes.

The long answer requires an understanding of what a pandemic is.

From the Wikipedia article:

Definition

According to the World Health Organization (WHO), a pandemic can start when three conditions have been met:[1]

* Emergence of a disease new to a population.
* Agents infect humans, causing serious illness.
* Agents spread easily and sustainably among humans.

A disease or condition is not a pandemic merely because it is widespread or kills many people; it must also be infectious. For instance, cancer is responsible for many deaths but is not considered a pandemic, because the disease is not infectious or contagious.

This is a generic pandemic definition, and not specific to influenza.

For the case of an influenza pandemic we will add the following:

Influenza pandemics occur when a new strain of the influenza virus is transmitted to humans from another animal species. Species that are thought to be important in the emergence of new human strains are pigs, chickens and ducks. These novel strains are unaffected by any immunity people may have to older strains of human influenza and can therefore spread extremely rapidly and infect very large numbers of people. Influenza A viruses can occasionally be transmitted from wild birds to other species causing outbreaks in domestic poultry and may give rise to human influenza pandemics.

So, what are we dealing with? The novel influenzavirus A(H1N1) that is currently circulating is, by definition, a new virus in humans (though containing genetic material from previous human strains of influenzavirus type A), it definitely infects humans and can cause serious illness, and is capable of sustained spread between humans. Furthermore, it is a new virus from a different species (pigs). Therefore, despite the WHO's attempts at not declaring a full pandemic, the "classical" conditions are met.

It bears repeating, a pandemic does not have to be highly lethal, it has to infect humans in large portions of the world. The "Swine Flu" is doing just that, and the virus doesn't care what people say about it.

Why the concern

The novel strain of A/H1N1 influenza (swine flu) represents a potential threat to the health and lives of a large segment of the population worldwide. Although many are choosing now to discount this threat, it still remains despite the "mild" nature of the illnesses produced thusfar.

For those who want to look at the number of people officially listed as having become infected and those who died, here is what the World Health Organization says as of 5/11:

Influenza A(H1N1) - update 25

That translates out to around 1.13%. Seasonal influenza kills about 0.001% worldwide (citation needed). Granted, there are real problems with the numbers but out by the WHO, but for those who would point to that as evidence this is nothing bad, you have to look at what else the numbers say.

There is also the concern that the H1N1 and H5N1 (bird flu) viruses could meet in, perhaps, a pig or human, and the resulting virus could be highly transmissable like the novel H1N1 and with the high fatality rate of H5N1 (50-60% of persons infected with H5N1 die) (citation needed).

To be continued....

Diary of a Flu Year

This blog is meant to be a chronicle of what, in May 2009, looks to be the start of the first flu pandemic in 40 years.