Earlier this month the World Health Organization announced that the H1N1 flu (swine flu) worldwide epidemic is over. The H1N1 pandemic was surprisingly mild compared to previous pandemics. Although it killed approximately 18,000 people worldwide, the flu’s fatality rate was only comparable to that of seasonal flu. Part of the reason for H1N1’s relative mildness was attributed to swift action by world governments and a very effective influenza vaccine.

H1N1 originally broke out in Veracruz, Mexico, in spring 2009. By June it was declared a pandemic by the Centers for Disease Control and Prevention. Spread by droplets expelled by the infected subject, the influenza virus followed typical transmission routes for seasonal flu. The flu’s symptoms include fever, cough, headache, and fatigue.

What made H1N1 unusual were its victims. While the elderly and adults with compromised immune systems were at higher risk to catch the disease, the influenza was particularly fatal to children with chronic health problems. In fact, it was far more lethal to that segment than seasonal flu.

Though the flu vaccine recommended for the 2010 flu season contains the H1N1 vaccine, WHO’s recent announcement should allay fears of an H1N1 influenza pandemic like that of last season.