An mRNA flu vaccine can be manufactured more quickly than traditional egg-based flu vaccines, making it more responsive to changing flu threats.

mRNA and other technologies used for COVID-19 vaccines are being applied to influenza research. Scientists hope these advances will lead to a universal flu vaccine that protects against multiple strains and reduces the need for yearly shots.

After influenza B was identified in 1940, researchers created a two-strain vaccine by 1942. The WHO later built a global surveillance system to track mutations, enabling vaccines to be updated annually to target the strains most likely to circulate.

For decades, influenza vaccines have been made by growing viruses inside fertilized chicken eggs. Though newer methods using cell cultures or recombinant technology exist, egg-based production remains the primary global manufacturing process.

Flu vaccination typically reduces the risk of medical visits by 30 to 60% and lowers hospitalization rates by around 40%. Between 2023 and 2024, in the US alone, vaccines prevented an estimated 120,000 hospitalizations and nearly 7,900 deaths.

The body needs a few weeks after the vaccine to build up a sufficient antibody response, which eventually wanes. Scheduling the vaccine accordingly can maximize its effectiveness when flu season ramps up.

In this video, Yale experts Saad Omer, MBBS, MPH, PhD; Onyema Ogbuagu, MBBCh; and Akiko Iwasaki, PhD, explain the science behind COVID-19 mRNA vaccines.

Antigenic shift happens when two different influenza viruses infect the same host and swap genetic material. The result is a brand-new subtype of influenza which, if easily spread among people, can trigger a worldwide pandemic.

As viruses mutate and develop, vaccines have to adapt, leading to regular recommended injections like flu shots. Researchers are working to develop universal vaccines that aim to protect against multiple virus variants if not entire virus families. These vaccines work by creating broadly neutralizing antibodies (bnAbs) that target aspects of viruses that don't typically mutate and are integral to the virus' survival.

As of early 2026, there was no vaccine for Lyme disease available. One candidate vaccine, VLA15, was in later-stage clinical trials. Another designed to provide seasonal protection was licensed to a pharmaceutical company in 2025, and was planned for human clinical trials.

Unlike the common cold, influenza attacks suddenly with fever, body aches, and fatigue. Seasonal strains circulate worldwide, infecting up to a billion people each year and causing hundreds of thousands of deaths despite vaccines and treatments.

The surge in HFMD in the summer and early fall of 2025 in the mid-Atlantic could be the result of a confluence of factors, including a more virulent strain of disease-causing virus, good environmental conditions for the virus to spread—hot, humd—and a potential immunity gap among kids due to milder HFMD outbreaks the previous year.

Collaborations between the military, biotech, and academic researchers led to an experimental antibody treatment for the Andes hantavirus strain—the one that more readily passes between humans. As of spring 2026, it had only been tested in animals. The US Army has also tested a potential hantavirus vaccine in people. It published early findings in 2023 that seemed promising, eliciting some immune system response.

First detected in Mexico, the 2009 “swine flu” pandemic infected up to 1.4B people worldwide. While mortality rates were lower than earlier pandemics, the outbreak still caused more than 150,000 deaths.

Influenza viruses carry two key surface proteins: hemagglutinin (H), which lets them enter cells, and neuraminidase (N), which helps them escape and spread. These proteins are the basis for the names of flu subtypes like H1N1 and H3N2

The 1957 H2N2 pandemic spread from East Asia, killing more than 1M globally, while the 1968 H3N2 pandemic began in Hong Kong and caused a similar toll, with both strains rapidly moving across continents.

Accounts of flu-like illness appear as early as 412 BCE, when Hippocrates described a sudden wave of cough and fever. Centuries of recurring outbreaks culminated in the first clearly documented pandemic in 1580, spreading from Asia into Europe and Africa.

Accounts of flu-like illness appear as early as 412 BCE, when Hippocrates described a sudden wave of cough and fever. Centuries of recurring outbreaks culminated in the first clearly documented pandemic in 1580, spreading from Asia into Europe and Africa.

Some vaccines, like those for measles, rely on weakened versions of a virus. These weakened pathogens are introduced into the body, triggering an immune response and helping the immune system learn to protect itself against stronger versions of the virus. (This also explains why some vaccines make you feel under the weather.)

The live virus vaccine, delivered via oral drops, induces the best protection in the body. Because it includes a live, weakened form of the virus there's an extremely small risk it can sicken recipients and potentially cause paralysis. Recipients also shed the virus in their stool, which can rarely lead to vaccine-derived cases of the virus if the virus mutates.

Watch experts weigh in on the prevailing business models of vaccine production, including how the Covid-19 pandemic has disrupted the industry for good in this 20-minute video from Financial Times.

This interactive 3D model reveals the influenza virus’s structure—its outer coat and spike proteins—and compares it with other well-known viruses, offering a clear view of how flu differs from pathogens like HIV or coronaviruses.

The World Health Organization estimates that seasonal influenza causes about 1B cases annually, including 3 to 5M severe illnesses and between 290,000 to 650,000 deaths.

The rapid global spread of H5N1 bird flu—from remote Antarctic islands to US farms—shows how animal spillover, driven by human activity and ecological disruption, is accelerating pandemic risk across species long before sustained human transmission begins.

In their flu episode, cohosts Erin Welsh and Erin Allmann Updyke unpack influenza's biology, history, and impact—explaining everything from past pandemics to modern vaccines, all with their trademark mix of science and storytelling.

This article provides an in-depth historical account of the 1918 Spanish Flu pandemic, including its impact on the global population and how its occurrence spurred significant advancements in the study of viruses—laying the groundwork for the...

Rest, fluids and common medicines usually ease influenza symptoms. For people at higher risk of complications, doctors may prescribe antiviral drugs, which work best when started soon after symptoms begin.

Federal guidance currently recommends a two-shot schedule of the MMR vaccine for children in most cases, once at 12 to 15 months and once at 4 to 6 years. (A September 2025 update only called for the elimination of a combined vaccine that included protection against varicella, the MMRV shot.)

Sampling of wastewater in London in 2022 detected fragments of polio virus, suggesting a vaccine-derived version of polio may be circulating. No one became ill, but the finding did trigger calls for a renewed booster inoculation campaign.

As many as a quarter of MS patients have antibodies in their blood that bind to both a central protein in Epstein-Barr virus and a protein made in the brain and spinal cord that—when attacked—leads to a breakdown of protective nerve fiber insulation. This suggests the immune system's primed to attack the nervous system after mounting a defense against Epstein-Barr.

Modern pandemics have been defined by the race between globalization (which increases risk) and the development of new medicines. The Great Influenza epidemic claimed some 50 million lives, and the COVID-19 pandemic killed more than 7 million. In between, diseases like Ebola, cholera, AIDS, and more have devastated communities.

The 1580 influenza pandemic, traced from Asia to Africa and into Europe, became the first flu outbreak clearly documented across the continent—killing tens of thousands and highlighting influenza’s potential for rapid global spread.

There are three recommended cholera vaccines on the market. The number of required shots and the period of protection they provide vary, but each of them can be life-saving.

The 1918–1920 flu pandemic (once called, incorrectly, the Spanish flu) killed quickly and in huge numbers, with estimates of the global death toll ranging from 50 to 100 million people. Several factors contributed to the high mortality rate: lack of antibiotics, the global disruption of World War I, and more.

A major hurdle for West Nile vaccine development is the lack of a market for it since so many people are symptomatic for the infections. Still, a growing number of infections, including a 40% spike in 2025, may change that calculation.