Pandemic Influenza (H1N1)

Influenza A(H1N1) is caused by a new influenza virus, first identified in March 2009. The virus, technically termed "2009 H1N1" had never before been found in humans. Initially, it was referred to as "swine flu virus" because studies showed that it was a combination of genes present in the influenza viruses that infect pigs (swine), as well as birds and humans. In the current influenza pandemic, the virus spreads from person to person. It is in no way related to any previously identified virus or to the human virus responsible for the seasonal influenza most prevalent in winter(1).


Signs and symptoms of Influenza A(H1N1)

Influenza A(H1N1) causes much the same symptoms as seasonal influenza. The onset of A(H1N1) infection is marked by the typical flu syndrome, consisting of fever, cough, headache, muscle and joint pain, malaise, sore throat, runny or stuffy nose, and in some cases vomiting and diarrhea(1).

The new A(H1N1) influenza appears to be as contagious as seasonal flu and spreads rapidly, particularly among people in the 10- to 45-year age group. Like seasonal flu, the severity of the disease ranges from mild to sometimes fatal(1).

On 11 June 2009, the World Health Organization (WHO) raised its pandemic alert level from 5 to 6, the highest alert level triggering the launch of the WHO's global pandemic preparedness and response plan(2).


Epidemiology and prevention of Influenza A(H1N1)

The influenza A(H1N1) virus spreads from person to person as easily as the usual seasonal influenza virus. Transmission occurs via droplets released by an infected person when coughing or sneezing, or through touching contaminated hands or objects(1).

To reduce transmission, infected individuals should cover their noses and mouths when coughing or sneezing, remain at home when feeling ill, wash their hands regularly and stay as far away as possible from healthy people.

Vaccination is one of the most effective means of protection during influenza epidemics or pandemics. Antiviral medicines, the social distancing and complying with the rules of personal hygiene can also help to prevent spread of the infection(3).


1- What is the new influenza A(H1N1)?
(accessed 8 October, 2009)

2- World now at the start of 2009 influenza pandemic, Dr Margaret Chan Director-General of the World Health Organization
(accessed 8 October, 2009)

3- Vaccines for pandemic influenza A (H1N1)
(accessed 8 October, 2009)