Flu (seasonal, swine, avian and Spanish) and SARS compared

Do you notice any marked similarities or differences?

  Seasonal flu 2009 swine flu H5N1 avian flu 1918 Spanish flu SARS (severe acute respiratory syndrome)
Virus type Influenza A and B Influenza A Influenza A Influenza A Coronavirus
Influenza subtype H1N1/H3N2 H1N1 H5N1 H1N1 n/a
Route to humans Humans Pigs Wild birds via domesticated birds Birds, possibly via pigs or directly Bats via small mammals
Transmissibility Moderate High Human-to-human transmission rare High Moderate
Symptoms Fever, cough, aching, tiredness, sore throat, runny nose Same as seasonal flu, sometimes with diarrhoea or stomach upset Same as seasonal flu, plus fluid build-up in the lungs, severe breathing problems, chest pains Same as avian flu, plus lung problems and pneumonia Same as avian flu, plus pneumonia
Estimated death rate 0.1% 0.1% or less 60% 2–20% 10%
Deaths (global) 250,000–300,000 (annual) 18,500 (WHO figure); contributed to estimated 120,000–280,000 deaths 393 (as at October 2014) 50–100 million (total) 447 (total)
Deaths (UK) Typically 3,000–4,000; in severe years, up to 30,000 457 (but likely contributed to far more) 0 250,000 0
At-risk groups Elderly, frail, those with heart and lung problems or diabetes Initially, infants, pregnant women, those with underlying health problems; later waves affected older people more All Unusual peak in deaths of young adults Older adults, those with underlying health problems
Summary Underappreciated annual killer Fortunately, only a mild pandemic Extremely nasty, but not yet spreading in people Killed more people than World War I We got lucky: low transmissability and draconian public health measures stamped it out before it could spread widely



About this resource

This resource was first published in ‘Influenza special issue’ in October 2009 and reviewed and updated in January 2015.

Statistics and maths, Microbiology, Ecology and environment, Health, infection and disease
Influenza special issue
Education levels:
16–19, Continuing professional development