Influenza, or the flu, is a well-known viral disease that affects the respiratory system — the nose, the throat, and sometimes the lungs as well.
These flu statistics are here to remind us that this infection is highly contagious, spreads mostly from person to person, and can lead to severe complications, including death.
Every year there is a seasonal flu epidemic costing billions in medical visits, medications, and economic losses.
However, since the symptoms may vary from season to season, it is useful to know the essential stats and facts about the flu.
Read the latest, science-based factual update on this breath-taking topic.
Top 10 Flu Stats and Facts
- The Spanish flu pandemic from 1918–1919 was considered the single deadliest in human history.
- Each year, between three and five million people get a severe form of flu globally.
- Up to half a million people worldwide succumb to flu symptoms every year.
- Between 3–11% of all Americans get sick from the flu each year.
- Flu incidence varies due to the severity of the flu season, statistics show.
- The severe course in younger, healthy people may be due to the immune system.
- Pneumonia is the most frequent complication of the flu.
- People 65 years and older, with certain chronic medical conditions, are at higher risk of complications during flu season.
- An average of 200,000 US citizens is hospitalized each year due to flu-related complications.
- The best way to protect oneself from a flu infection is to get vaccinated each year.
Historical Influenza Facts
1. The word “influenza” has Italian roots, whereas “la grippe” comes from French.
The Italian people linked the sudden and widespread sickness with the influence (the alignment) of the planets, the stars, and the Moon. As a result, the English adopted the term “influenza” in the mid-eighteenth century. However, the French had an entirely different word for the condition — “la grippe,” namely, “to grasp or hook.”
One of the most exciting flu facts is that a similar-sounding word was also used in Arabic — “anf-al-anza.” The word was used to describe the “nose of the goat,” whether due to the redness of the flu-affected swollen nose or because they thought that goats were the carriers of the disease.
2. Four major global flu pandemics were recorded since 1900.
The first one was called the Spanish flu pandemic (1918–1919), which was estimated to have killed between 50 and 100 million people worldwide. Flu death statistics were supplemented by the Asian flu pandemic (1957–1958), which started in China and killed between one and four million people.
The third flu pandemic that originated in Hong Kong (1968–1969) was responsible for killing approximately one million people. The most recent pandemic was the swine flu (2009) that killed around half a million people worldwide.
3. The Spanish flu pandemic from 1918–1919 is considered the single deadliest flu pandemic in history.
These gloomy influenza statistics state that the Spanish flu killed more people in just a few weeks than AIDS did in more than twenty years. In addition, more Americans died from the Spanish flu than in both World Wars, as well as the Korean and Vietnam Wars combined. Furthermore, scientists predict that in each century we have to anticipate two or three pandemics of such magnitude.
4. During the Spanish flu pandemic, alternative medicine prospered like never before.
Exotic treatments such as “grippura,” drinking whiskey, smoking cigarettes, icy water, and bleeding were among the most common practices. However, some flu trends such as open surgical procedures, i.e., evacuating pus and blood from the pleural cavity, were rarely successful.
5. Approximately 40 million Americans were vaccinated when a variation of the swine flu started circulating in the US in 1976.
The vaccine to A/Victoria/75 H3N2 eventually caused around 500 cases of Guillain-Barre syndrome leading to the cessation of vaccination and intensive litigation.
6. The cause of the swine flu (H1N1) was specified as a descendant of the sophisticated Spanish flu strain.
Spanish flu facts also include the common ancestry of the swine flu and the deadliest flu that caused the 1918 pandemic. Moreover, the whole structure of the virus is of the sort that affects pigs — hence the name.
7. The first flu vaccine was developed by Thomas Francis and Jonas Salk in 1944.
The early flu vaccines often caused fever, headaches, and other side effects due to the impurities found inside. Nevertheless, the flu vaccine has been in use for more than 60 years now.
Epidemiological Influenza Statistics Worldwide
8. Each year, between three and five million people around the world get a severe form of flu.
It was also estimated that tens of millions of people get milder or even subclinical forms of the disease.
9. Worldwide up to half a million people die of the flu every year.
The death cases caused by flu each year fluctuate between 250,000 and 500,000 globally, depending on the influenza subtype (i.e., type A flu).
10. Flu (2020) outbreak statistics showed increased influenza activity in North America with all seasonal influenza subtypes in circulation.
However, it’s not just North America that’s affected by a possible influenza epidemic; influenza activity in other parts of the world, including Europe, Western Asia, East Asia, and Central Asia, is also on the rise. Still, some good news, the epidemiological situation in Northern Africa is currently under control.
Epidemiological Flu Statistics in the USA
11. Between 3–11% of all Americans get sick from the flu each year.
The symptomatic flu illness is observed in about 8% of the US population, depending on the season. Although the predicted rates are between 5% and 20%, the actual prevalence is much lower. It was estimated that this average 8% translates roughly into 26.18 million Americans getting the flu, 31.4 million visiting the doctor, and some 200,000 ending up hospitalized.
12. Flu incidence varies according to the severity of the flu season.
According to the CDC, flu statistics of people who get sick change depending on the severity of the flu form. For example, in the 2011–2012 season, H1N1 was the predominant virus associated with a 3% incidence rate. On the other hand, during the 2012–2013 season, H3N2 was the predominant virus, leading to 11% of the US population getting sick.
13. The peak of flu season in the US is between December and February, as flu statistics from 2017 reveal.
Although flu activity varies from season to season (in addition to influenza viruses circulating year-round), the flu season starts around fall and winter and rarely lasts as late as spring. CDC’s Flu Peak Activity Chart showed that February is, in fact, the peak month — the rate of infections, hospitalizations, and deaths are highest during this period in particular.
Medical Facts About the Flu
14. Flu viruses can survive between 24–48 hours on hard surfaces and about 15 minutes on tissues.
The flu virus is contagious for around 24–48 hours on hard, nonporous surfaces, but can endure only minutes on clothes, human tissues, and hands. Therefore, hand washing and disinfecting remain one of the most effective measures against the flu. What’s more, at human body temperature, the virus can live up to a week; at freezing temperatures, it can live well over 30 days.
15. Flu is an RNA virus belonging to the Orthomyxoviridae family.
One of the interesting facts about influenza is that the nucleic acid of the flu virus is encased in a shell (capsid) and further covered by a fatty membrane called an envelope. Also, the name Orthomyxoviridae comes from the Greek word “orthos” meaning “straight” and “myxa” — “mucous.”
16. The severe flu-cases in younger, healthy people develop immunologically.
Flu deaths statistics for the 2009 H1N1 influenza showed that the unexpectedly high death-rates in younger people, without a previous medical condition and in good physical shape, might be associated with the overreacted immune system.
The hyperactive immune cells cause the so-called “cytokine storm,” which leads to the damage of many organs and systems in the body, and eventually death. The same phenomenon might be responsible for the highest death rates recorded during the Spanish flu pandemic of 1918–1919.
17. The most frequent flu complication is pneumonia.
Flu deaths per year chart demonstrates that bacterial pneumonia is the most common flu-related complication and the leading cause of death in patients with flu, regardless of the powerful antibiotics we have today.
18. Children between 0–17 years are most likely to develop symptomatic flu infection.
(Clinical Infectious Diseases)
Children younger than 18 years are more than twice as likely to get sick from the flu than adults 65 years of age and older (9.3% vs. 3.9%, respectively). Median incidence values for adults are estimated at 8.8% according to flu prevalence statistics.
19. The infected person can spread the flu virus for about one day before the appearance of symptoms.
This is a serious issue as one can infect others before even realizing that they too are infected. The most contagious days are the first 3–4 days of the infection. Usually, people stop being contagious 5–7 days after the onset; however, children and people with a compromised immune system can spread the flu viruses for longer.
20. People aged 65 years and older, and/or with certain chronic medical conditions, are at higher risk of complications during flu infection.
Statistics on the flu demonstrated that older people — and people of any age but with chronic diseases such as diabetes, lung, heart, renal, metabolic, liver or hematologic diseases, cancer, etc. — are at high risk of developing severe flu-associated complications.
Pregnant women and children under the age of 5 are also at a higher risk, as well as the immunocompromised, such as HIV patients, people with primary immune deficiencies, or those receiving chemotherapy and steroids.
Healthcare workers are also at high risk of getting infected due to the increased exposure to sick patients in health centers where influenza prevalence is also high.
21. The average time for symptoms to start occurring is around two days.
Typically, the symptoms are observed in about two days after exposure. However, the period can be anywhere between one and four days.
22. The other name for the Spanish flu is “the purple death.”
One of the most interesting flu trivia is that its worst symptom — called “heliotrope cyanosis” — is often referred to as a messenger of death. The purple, black, or blue colors of the face which appear in terminal phases of the disease are due to lower levels of oxygen caused by lung dysfunction.
Flu Statistics on Complications and Death
23. One-third of all hospitalized children had a non-respiratory clinical diagnosis.
In 2019, 33% of all hospitalized children were admitted with non-respiratory viral symptoms, such as sepsis, febrile seizures, dehydration, etc. In these cases, the laboratory confirmation of the diagnosis by rRT-PCR and serology was crucial.
Between 140,000 and 960,000 infected people get hospitalized, leading to 3,000 to 79,000 deaths per year, as shown by CDC flu trends.
Comparing cold vs. flu stats: the common cold is not a life-threatening infection and is rarely associated with hospital admissions.
25. Influenza-associated mortality depends on the age.
People younger than 65 years have lower flu-related mortality rates (0.1–6.4/100,000 individuals), whereas people between 65 and 74 years of age have an estimated mortality rate of 2.9–44.0/100,000; the most frightening of all, however, is the mortality rate of those older than 75 — a whopping 17.9–223.5/100,000!
26. The seasonal influenza-associated respiratory deaths depend on the location.
The flu activity map verified that the highest mortality rates were recorded in Sub-Saharan Africa (4.0–8.8/100,000 individuals) and Southeast Asia (3.5–9.2/100,000). Nevertheless, people older than 75 years of age still hold the “record” for the highest influenza mortality rate regardless of the flu map.
27. The 2017–2018 influenza season was considered one of the deadliest in decades.
Flu statistics from 2018 depicted the 2017–2018 flu season as one of the most dangerous in recent times, with high levels of visits recorded for flu-like illnesses (both at outpatient clinics and emergency departments). The flu-associated hospitalizations were more than 900,000; over 80,000 people died because of it.
Around 200 children died during the 2017–2018 flu season, according to official reports at the end of 2018. Among them, 80% have not been vaccinated. As for older people, up to 65% of them develop a fatal bacterial infection. Therefore, 70–85% of all seasonal flu-related deaths have occurred among the elderly.
Flu Shot Facts that Are Good to Know
29. The best way to protect oneself from possible flu infection is to get vaccinated each year.
Although available as both a nasal spray and an injection, it takes approximately two weeks for the flu vaccine to develop antibodies, regardless of the method of administration. A flu vaccine protects against 3–4 flu strains, which are determined each year.
The CDC insists on an annual flu shot for everyone, including babies older than six months because the vaccine reduces the chance of being infected by 40–60% according to flu vaccine effectiveness statistics.
Flu shot side effects may include local symptoms on the skin and are closely associated with headaches, fever, nausea, and muscle aches but generally, the vaccine has an excellent safety profile.
30. Three million doses of flu vaccines were produced for the 2017–2018 season.
The production process of the flu vaccine includes an egg-based manufacturing procedure used for over 70 years. The latest version of the flu vaccine, approved for use in the US in 2013, was made with the help of gene-recombination technology.
31. Flu vaccine statistics estimated that more than 5.3 million illnesses were prevented during the 2016–2017 influenza season.
As the chance of contracting the disease gets lower, the number of medical visits and hospitalizations also decreases — around 2.6 million visits and more than 85,000 hospitalizations related to the influenza virus were prevented. Flu shots also alleviate the severity of influenza symptoms.
Nevertheless, the overall risk of flu-associated deaths was cut by half among children with chronic medical conditions, as well as by two-thirds among healthy children according to a 2017 study.
33. The overall effectiveness of the flu vaccine in the 2017–2018 season was estimated at 40%.
The flu vaccine had a 40% effectiveness against both influenza A and influenza B which counts as a 40% reduction in overall flu contraction, seeking medical help, and being hospitalized, influenza statistics from 2017 indicate.
34. The coverage of flu vaccination does not yet reach the national public health goals of 80%.
(National Foundation for Infectious Disease)
Flu coverage has still not reached the desired 80%. For 2016, the coverage dropped from 59% to 57.9% in the adult population, whereas it remained steady among children aged 6 months to 17 years.
35. Up to 169 million influenza vaccine-doses were projected for the US market for the current season.
The supply of flu vaccines depends on private manufacturers. For the flu season of 2019–2020, the expected doses of flu vaccines are anywhere between 162 and 169 million. These 2019–2020 flu shot doses are not only intended for the American market but also for abroad use.
36. Each year more than 90 million Americans get a flu shot.
Even though the incidence of flu and flu-related complications is higher, about 90 million US citizens get their flu shots. It is safe to say that if the flu coverage was higher, there would have been fewer deaths in 2019.
Flu Stats: the Economic Burden of Influenza
37. In the US, 17 million workdays are missed per year due to flu infections.
The estimated cost of sick days is $7 billion in total, whereas the annual direct costs (for medical visits and medications) are approximately $4.6 billion.
These expenses have since increased; $21 billion is projected for the 2017–2018 season with direct medical costs of around $10 billion (spent on flu-related medical visits and hospitalizations). The total economic burden of seasonal influenza to American society was about $11.2 billion, also confirmed in the CDC flu-stats report.
38. Children who get the flu, miss an average of 3–5 school days.
(S.C. Department of Health and Environmental Control)
Apart from the educational difficulties due to illness, teachers and caregivers have to be aware of the early symptoms of the flu as well as the urgent warning signs that require immediate medical attention. Children under two years of age are especially vulnerable as the chances of them developing flu-associated complications are also higher, according to CDC flu facts.
(National Center for Health Research)
It was medically proven that taking Tamiflu in the first 24–48 hours after the onset of the first flu symptoms can greatly help in the recovery process — one day faster, to be exact — compared to those that do not take any anti-flu medications whatsoever.
According to the CDC, one of the most interesting facts about the flu is that it caused approximately 350,000 hospitalizations and 20,000 deaths during the 2019/20 season, with an estimated 34 million illnesses.
Until the 19th of March, the coronavirus outbreak caused a total of 9,464 hospitalized cases and 155 deaths in the US.
When compared, according to the number of total cases, hospitalization rates in coronavirus are almost ten times higher.
41. Both seasonal flu viruses and CoVid-19 cause respiratory illness, but progress with slightly different symptoms.
Typical flu symptoms come on suddenly and include sore throat, muscle aches, fever, cough, and headache. However, they also cause stuffy and runny nose and vomiting and diarrhea, according to the official flu statistics from 2019.
According to the epidemiologists, about 80% of coronavirus patients develop a dry cough and more than 90% develop fever. However, only 11% to 44% develop fatigue or muscle aches. However, other flu-like nasal and digestive symptoms have seldom been recorded.
(Journal of Travel Medicine)
The average number of people who can catch the virus from a single people-based reservoir is 1.3.
On the other hand, one person infected with CoVid-19 can spread the virus to between 2 to 3 persons, which makes it twice as transmittable.
43. According to flu statistics, CoVid-19 is more deadly than influenza.
As of March 19th, 2020, the disease caused by coronavirus proved deadly in 3.5% of the cases, in contrast to the influenza mortality rate which remains 0.1%.
In contrast to 1-4 days needed for a flu incubation, the CoVid-19 studies suggest that 97.5% of people develop symptoms within 11.5 days of the exposure. According to these insights, it is estimated that only 1% of the infected people could still be contagious after a 14-day quarantine.
What is the incubation period for the flu?
The incubation period of the virus is one to seven days. Sick people may remain contagious for another five days after the first symptoms of flu have been manifested. Since some of the patients have mild forms of flu infection, they may infect several people around them without knowing.
What are the symptoms of the flu?
The symptoms of the patients and the overall clinical picture are quite typical for the seasonal flu. These include headaches, fever, shivering, coughing, sore throat, runny nose, tiredness, and fatigue. The peculiarity of this year’s flu is that it mainly targets young people.
How does the flu kill?
Аbout a third of the people who experience flu-related complications die due to the virus overloading the immune system (e.g., the so-called cytokine storm); others die from secondary bacterial infections, usually in the lungs (i.e., pneumonia); and the remaining patients die due to the damage done to one or more organs (i.e., myocarditis, etc.). The same complications characterize the 2019–2020 flu.
How to treat the flu?
The flu is treated with traditional remedies, and in the case of severe illness — with antiviral drugs that are available only with a prescription. There are currently a few drugs that are most effective against influenza A, such as oseltamivir and zanamivir.
The sooner the medications are administered, the more effective the treatment. Therapy with them usually lasts for five days. Antiviral drugs can be given to children as well, but at lower doses, the same goes for pregnant women.
When to get a flu shot?
October and November are the most appropriate months for getting vaccinated if you want to be well-protected in January when the most severe flu wave hits. Furthermore, two to three weeks are needed in order for the immune response to develop after vaccination.
Anyone that follows today’s flu report knows very well that the infection can knock you down at any time. If we want to keep an eye on the 2020 flu season, it is crucial to track all the key indicators such as flu activity and severity (estimated by hospitalizations and deaths).
The more we know about the flu, the more educated and prepared we will be, especially on topics such as when the flu season starts, what the effectiveness of flu vaccine is, and how to treat the infection to avoid further unpleasant complications.
The essential flu statistics provide us with vital knowledge and help us recognize the early symptoms, allowing us to take immediate preventive measures.
- Clinical Infectious Diseases
- JAMA Network
- Journal of Travel Medicine
- Malaysia today
- Mayo Clinic
- National Center for Health Research
- National Foundation for Infectious Disease
- S.C. Department of Health and Environmental Control
- Science Alert
- Science Daily
- Science Daily
- Science direct
- The Lancet