When was the last global pandemic and how long did it last?

Swine flu (H1N1 flu), in 2009, was the virus responsible for the last global pandemic before Covid-19. 

The virus was first identified in Mexico and became known as swine flu because it’s similar to flu viruses that affect pigs.

The World Health Organisation (WHO) declared the H1N1 flu a pandemic after it caused respiratory infection in humans. 

It was the third virus to be declared a pandemic after the 1918 “Spanish flu” and the 1977 “Russian flu”.

“After early reports of influenza outbreaks in North America in April 2009, H1N1 flu spread rapidly around the world. By the time WHO declared a pandemic in June that year, 74 countries and territories had reported laboratory-confirmed infections,” said WHO. 

“Unlike typical seasonal flu patterns, the virus caused high levels of summer infections in the northern hemisphere, and then even higher levels of activity during cooler months. The virus also led to patterns of death and illness not normally seen in influenza infections.”

How many people died of H1N1 flu?

According to the US Centers for Disease Control and Prevention (CDC), about 151,700 to 575,400 people worldwide died from H1N1 flu during the first year it circulated.

Globally, 80% of H1N1-related deaths were estimated to have occurred in people younger than 65. 

The number of “Spanish flu” related deaths was estimated to be at least 50-million globally and for the “Russian flu” about 1-million. 

How long did the H1N1 flu pandemic last?

In August 2010, WHO declared the pandemic over, saying it had “largely run its course”.

It’s now described as seasonal flu and is included in the annual flu vaccine.

“Based on experience with past pandemics, we expect the H1N1 virus to take on the behaviour of a seasonal influenza virus and continue to circulate for some years to come,” WHO said at the time. 

“In the post-pandemic period, localised outbreaks of different magnitude may show significant levels of H1N1 transmission.

“The virus did not mutate during the pandemic to a more lethal form. Widespread resistance to oseltamivir did not develop. The vaccine proved to be a good match with circulating viruses and showed an excellent safety profile.”

“Spanish flu” lasted for two years while “Russian flu” lasted for a year. 

The “Spanish flu” pandemic occurred in three waves, spring, autumn and winter, and was the most severe pandemic in history.

What are the symptoms of H1N1 flu?

The signs and symptoms of flu caused by the H1N1 virus are similar to those of infections caused by other flu strains and include:

• Fever
• Chills
• Cough
• Sore throat
• Runny or stuffy nose
• Watery, red eyes
• Body aches
• Headache
• Fatigue
• Diarrhoea
• Nausea and vomiting

Flu symptoms developed about one to three days after exposure to the virus.