Getting your questions ready
Getting your questions ready
Beat the crowd
10 questions No timer
50 free Influenza trivia questions with answers — science & nature quiz, new questions added Aug 2026.
This influenza trivia quiz covers the flu as a disease, a virus and a piece of history. It opens with the basics that most people get roughly right: how long the incubation period is, how many virus types there are, what the H and N in H1N1 stand for, and which animals are the reservoir. From there it goes into the biology that decides each winter: antigenic drift and shift, mixing vessels, why the vaccine has to be remade every year, how the strains are chosen and why most doses are grown in chicken eggs. The second half is history. The first convincing pandemic in 1510, the German bacteriologist who blamed the wrong microbe in 1892, the discovery of the virus in the 1930s, the first vaccine in 1945, and the pandemics of 1918, 1957, 1968, 1977 and 2009 with their subtypes, origins and death tolls. It also visits bird flu in Hong Kong, the antiviral made from star anise, the H5N1 case fatality rate, and the Italian astrological phrase that gave the disease its name. For the deadliest outbreak of all, see our separate Spanish flu quiz. Every answer was checked against Wikipedia's articles on influenza, its vaccines, drugs and pandemics, and each question links to the page that establishes it. Fifty questions, free, with an explanation after every answer.
30 of 50 questions with answers and explanations. Play the quiz
Q 01How long after exposure do influenza symptoms typically begin?
About two days
The incubation period runs one to four days, and symptoms usually last two to eight days.
Q 02How many types of influenza virus are there?
4
Types A and B cause seasonal epidemics, C causes mild illness mainly in children, and D is found in cattle and pigs.
Q 03Which animals are the primary reservoir of influenza A viruses?
Aquatic birds
Ducks, geese, shorebirds and gulls carry them; the virus also circulates in pigs and marine mammals.
Q 04Which type lives mainly in cattle and pigs and is not known to cause human illness?
D
It was only discovered in 2011 and is distantly related to type C.
Q 05In the subtype name H1N1, what does the H stand for?
Haemagglutinin
The N is neuraminidase; both are proteins in the viral envelope.
Q 06Which two influenza A subtypes have circulated together in humans since 1977?
H1N1 and H3N2
Both have been in seasonal circulation together since 1977.
Q 07How many H types have been isolated from wild birds?
16
Neuraminidase types run 1 to 11 in birds; H17, H18, N10 and N11 have been found only in bats.
Q 08Influenza B has no subtypes but two lineages named after which two places?
Victoria and Yamagata
The Yamagata lineage may have gone extinct around 2020-21 thanks to COVID-19 measures.
Q 09Which of the four contributes to seasonal epidemics but has never caused a pandemic?
Influenza B
It contributes to seasonal epidemics but does not reassort with animal strains the way A does.
Q 10What kind of genome do influenza viruses have?
Segmented negative-sense RNA
Types A and B have eight segments; the segmentation is what allows reassortment.
Q 11How many genome segments do influenza A and B viruses have?
8
They encode ten major proteins; C and D have seven segments.
Q 12What is the gradual build-up of mutations that changes a flu virus's antigens called?
Antigenic drift
It is the main reason flu vaccines have to be updated every year.
Q 13What is antigenic shift?
A sudden change when strains swap genome segments
When an animal strain reassorts with a human one, a novel pandemic-capable strain can emerge.
Q 21For how long is a person with flu usually infectious?
From a day before symptoms to 5-7 days after
Healthy adults shed virus for up to three to five days; children and the immunocompromised for weeks.
Q 22Most flu vaccines are manufactured by growing the virus in what?
Embryonated chicken eggs
The process takes six to eight months, which is why strains must be chosen well in advance.
Q 23How often does the WHO meet to choose flu vaccine strains?
Q 14Which animals are potential 'mixing vessels', carrying both bird and human flu receptors?
Pigs, bats and quails
Reassortment in such hosts can produce strains capable of human-to-human spread.
Q 15Which cell-surface molecule do influenza HA proteins bind to?
Sialic acid
Human viruses prefer alpha-2,6-linked sialic acids in the upper airway; bird viruses prefer alpha-2,3 links.
Q 16What is the most common symptom of influenza?
Coughing
Onset is sudden, and the illness is more severe than a cold but less likely to include a runny nose.
Q 17Which two bacteria most often cause secondary pneumonia after flu?
Streptococcus pneumoniae and Staphylococcus aureus
About a third of primary viral pneumonias are followed by a bacterial one.
Q 18Roughly what share of the population catches influenza in a typical year?
5 to 15 percent
That produces 3 to 5 million severe cases and up to 650,000 respiratory deaths worldwide.
Q 19Up to how many respiratory deaths does influenza cause globally each year?
650,000
Deaths fall mostly on young children, the elderly and people with chronic conditions.
Q 20Which age group is considered the most efficient spreader of influenza?
Children aged 2 to 17
Children with fewer past exposures shed more virus for longer.
Twice a year, once per hemisphere
Northern and southern hemisphere flu seasons fall at different times of year.
Q 24How are live attenuated influenza vaccines given?
Sprayed into the nose
Most flu vaccines are inactivated and injected intramuscularly.
Q 25How many strains do trivalent and quadrivalent flu vaccines cover?
Three or four
An H1N1, an H3N2 and one or two influenza B strains.
Q 26Oseltamivir must be taken within how many hours of symptom onset to be recommended?
48
It treats and prevents influenza A and B, and is also used to prevent infection in those at high risk.
Q 27Under what brand name is oseltamivir sold?
Tamiflu
Zanamivir, its inhaled cousin, is Relenza.
Q 28Oseltamivir synthesis starts from shikimic acid, originally extracted from which plant?
Chinese star anise
By 2006 about 30 percent of the supply was being made recombinantly in E. coli.
Q 29What was the first antiviral drug approved against influenza, in 1966?
Amantadine
Newer antivirals came into use from the 1990s.
Q 30Which bacterium was wrongly identified as the cause of influenza in 1892?
Haemophilus influenzae
R. F. J. Pfeiffer's mistake lives on in the bacterium's name.