Why WHO declared swine flu a pandemic

swine-flu-pandemicWe have been getting updates on swine flu for last two months that it was originated from Mexico and infected people across the globe.  Swine flu virus is contagious, spreading from one person to another and from one country to another. As of today, nearly 30,000 cases and 145 deaths have been reported in 74 countries including USA, Europe, South America and Australia. This is the prime reason that swine flu has been bucketed into the influenza pandemic category.  Newspapers are stacked up with the pandemic flu announcement that WHO (World Health Organization) chief Dr. Margaret Chan finally raised the level of influenza pandemic alert from phase 5 to phase 6 and declared first global influenza pandemic in 41 years. Do you know what these phases mean? Let us take a closer look at the terminologies used by the media and health organizations.


What do you mean by pandemic?

As per WHO, pandemic is a global disease outbreak. A flu pandemic occurs when a new influenza virus emerges for which people have little or no immunity and for which there is no vaccine. The disease spreads from person-to-person, causes serious illness, and can sweep across the country and around the world in relatively short time. An influenza pandemic may be caused by either swine (pig) or avian (bird) flu viruses.


How many phases are there to declare pandemic alert and what does that mean?





Estimated probability

of pandemic


Phase 1


No animal influenza viruses circulating among animals have been reported to cause infections in humans.

Phase 2

An animal influenza virus circulating among domesticated or wild animals is known to have caused infection in humans, and is therefore considered a potential pandemic threat

Phase 3

An animal or human-animal influenza reassortant virus has caused sporadic cases or small clusters of disease in people, but has not resulted in human-to-human transmission sufficient to sustain community-level outbreaks.

Phase 4

Medium to high

Human-to-human transmission (H2H) of an animal or human-animal influenza reassortant virus able to sustain “community-level outbreaks has been verified

Phase 5

High to certain

The same identified virus has caused sustained community level outbreaks in two or more countries in one WHO region.

Phase 6


In addition to the criteria defined in phase 5, the same virus has caused sustained community level outbreaks in at least one other country in another WHO region.  Designation of this phase will indicate that a global pandemic is under way.


Post-peak period

Levels of pandemic influenza in most countries with adequate surveillance have dropped below peak levels.

Possible New wave

Level of pandemic influenza activity in most countries with adequate surveillance rising again.

Post-pandemic period

Levels of influenza activity have returned to the levels seen for seasonal influenza in most countries with adequate surveillance.


Why Swine flu outbreak is considered as pandemic?

Swine flu virus could become a pandemic for the following reasons:

  • It is a never-before seen combination of human, swine, and avian influenza viruses.
  • It is being spread from human to human.
  • The age group most affected is healthy, young adults (unlike seasonal flu)
  • Like other influenza viruses, it continues to evolve. 

What are the treatments options for H1N1 flu virus?

Vaccines: WHO says that currently there is no vaccine available to protect humans against the infection of H1N1 virus. The H1N1 flu virus strains are very different from human H1N1 viruses and, therefore, vaccines for this past human seasonal flu would not provide protection from these H1N1 flu viruses.


class="MsoNormal" style="margin: 0in 0in 0pt; line-height: 150%; text-align: justify;">Antiviral Drugs: CDC recommends the use of oseltamivir (Tamiflu ®) or zanamivir (Relenza ®) for the treatment or prevention of infection with H1N1 influenza viruses.


Antiviral drugs have important roles in treatment and prevention. However, existing stocks of antiviral drug are unlikely to meet the demand. WHO is working closely with manufacturers to expedite the development of a safe and effective vaccine but it will be some months before it is available.


Masks: Wearing facemasks help you to protect from getting infected with droplets being spread by the person suffering with flu.


How many people have been infected by H1N1 flu virus?

Click the following picture to get latest information on number of cases reported for swine flu.



How many pandemic flu have been reported in 20th century?

Three major ones, Spanish Flue (1918), Asian Flu (1957) and Hong Kong Flu (1968).  Read more about these through: Pandemic Flu of 20th century.


How many death cases were reported during earlier pandemics?

Characteristics of the three Pandemics of the 20th century:



Area of


Influenza-A virus subtype

Estimated case fatality rate


mortality worldwide

Most affected age groups


Spanish Flu




20-50 Million




Asian Flu





1-4 Million



Hong Kong Flu





1-4 Million

All age



I think swift spread of H1N1 flu virus is another example of the quotation “It’s a small world”.  Globalization and World Wide Web (WWW) has made life easier in many respects.  On one hand the information is available worldwide in femto-seconds; either it is regarding an outbreak or treatments being developed against it.  On the other hand, travel has become easier and you can fly around the globe within 24 hrs.  Due to this fast travel across the globe, it is extremely difficult to cage spread of virus like H1N1 to one location.  Last year, we had bird flu that started in China and spread in many countries and now we have swine flu that emerged in Mexico and has spread to 74 countries.


I may not be able to provide the world with a solution to fight against H1N1 virus, but I can make people aware of the virus, its causes and precautions that can be taken against it.  It is highly essential to have general awareness about the virus and you can read: fact about swine flu.  I hope that we are able to contain the pandemic flu before it is fatal to the level seen in previous pandemics.  Stay safe and healthy reading.

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