The flu vaccine has evolved alongside discoveries of new virus strains

Flu vaccines are reformulated each year based on global predictions

Twice a year, health agencies analyze circulating influenza strains and select those most likely to spread in the coming season. Because vaccines must be produced months ahead, they represent the best available forecast.

Small genetic changes force flu vaccines to be updated regularly

Through a process called antigenic drift, influenza viruses accumulate tiny copying mistakes in their genes. These gradual changes alter the virus enough that immunity fades, making updated vaccines necessary each flu season.

COVID-19 vaccine breakthroughs are driving efforts toward a universal flu shot

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.

Most flu vaccines are still produced using chicken eggs

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.

What are universal vaccines?

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.

In 1933, the influenza virus was first identified through “ferret flu” experiments

In 1933, British researchers dripped filtered nasal fluids from a sick colleague into ferrets, which quickly developed “ferret flu.” This experiment proved influenza was viral, not bacterial, and established the basis for modern flu vaccines.

Annual flu shots remain the best defense against influenza

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.

How the 1918 pandemic spurred developments in virology and vaccines

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...

The flu is a contagious respiratory illness caused by influenza viruses

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.

Flu viruses use special proteins to invade and spread in the body

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

See the evolution of Ebola vaccine and treatment development.

Live virus vaccines predated polio—that's how we vaccinate against smallpox

Since 1796, smallpox vaccines have used a live poxvirus related to smallpox. Yellow fever vaccines have used a live weakened form of the virus responsible for yellow fever since 1937.

Two Lyme disease vaccines were in development in 2026

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.

The 1957 and 1968 influenza pandemics caused millions of deaths worldwide

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.

Explore 3D models of some of the most dangerous viruses

Everyone has come in contact with common viruses—typically something like influenza (the common flu)—but sometimes they encounter more dangerous strains. While we're familiar with the symptoms that manifest, it wasn't until the advent of advanced microscopy that scientists could pin down the exact structure and behavior of various viruses.

Learn the history and science of influenza in 'This Podcast Will Kill You'

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.

See the evolution of Ebola vaccine and treatment development

The recently approved vaccine and treatments against Ebola are the result of many years of investments and have reshaped how the world addresses Ebola outbreaks. Four drugs were tested in the midst of the 2014 outbreak. Two proved to be so effective the clinical trial ended early. The vaccine proved effective during the 2018-2020 outbreak in the DRC.

Only one strain of wild poliovirus continues to infect humans

Three strains of polio used to regularly infect humans, but two of the strains were declared eradicated in 2015 and 2019, respectively. In 2019, world health leaders estimated complete polio eradication—if achieved—would save $14B by 2050.

Why we don't have an answer for the common cold

Since a landmark study of the common cold in 1925, researchers have learned much more about the seasonal ailment. Despite continuous study, people still contract colds for similar periods of time at the same rate with the same symptoms, and there's no vaccine. This article explains how the many viral strains make it hard to control.

Environmental conditions, shifting immunity, and viral strain could help explain 2025 spike

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.

Experimental hantavirus vaccines and therapies, still under development, have long been funded by the US military.

There are two recommended malaria vaccines

Two vaccines are currently recommended by world health experts for children living in areas where malaria transmission is common. The first, RTS,S/ASO1, formally became recommended for use by the World Health Organization in October 2021, and the second was approved by the WHO two years later. Both have faced logistical, financial, and uptake challenges.

The measles vaccine has saved an estimated 94 million lives since its introduction

Measles killed an estimated 2.6 million people globally in 1980, after the development of a vaccine but before its widespread dissemination. By 2014, that figure had dropped to an estimated 73,000.

Wolbachia is a naturally occurring bacterium being employed to fight dengue

Scientists are fighting dengue spread in a roundabout way: injecting bacteria into Aedes aegypti mosquito eggs, which blocks the dengue virus from replicating in the tissue of mosquitoes. Researchers hope the bacterium will be passed to future generations, inoculating them against dengue. Wolbachia is also being investigated to combat other mosquito-borne diseases.

A history of vaccine rollouts

History tells us the public will tolerate risk of harm from a vaccine if their fear of the disease exceeds their fear of the vaccine.

Two-thirds of antibiotic classes were made between the 1940s and 1960s

The vast majority of bacterial treatments were developed during the "Golden Age of Antibiotics," an era of rapid innovation and drug discovery that led to the reduction of millions of deaths worldwide. Since 1970, only eight new antibiotic classes have been discovered.

Shingles vaccine may slow biological aging in older adults

Research published in 2025 that analyzed data from thousands of older adults found that those who had received the shingles vaccine exhibited signs of slower biological aging, such as lower levels of inflammation and slower epigenetic aging, than those who had not been vaccinated.

Budweiser stores yeast derived from the original 1800s strain in a secret bunker, which only the Head of Yeast Management can access—not even the CEO

This real-time tracking of the hantavirus cruise ship outbreak in May 2026 offers a unique glimpse into the global reach of the outbreak and whether the virus sickened passengers and their communities around the world.

At the beginning of the 20th century, a group of young men ate standard American food—replete with food additives like borax and formaldehyde—as part of government research to better understand food safety.

Visualize how CRISPR-Cas9—a type of immune system used by single-celled organisms to attack invasive viruses—targets and makes precise changes to a gene's DNA.

Indefinite cloning of some endangered species may not sustain their longevity because cloning success rates decrease as genetic mutations accumulate.

Hookworm infection, though risky, may help fight certain autoimmune conditions by tamping down the immune system's inflammatory response.

After 25 people used virtual reality headsets to practice flying with virtual wings—flapping their arms—their visual cortex responded to the wings almost as if they were real arms, treating them as body parts.

Fireworks-related ER visits are on the rise—in 2024, they increased by 52% as compared to the prior year.

As of 2025, the most cited papers in science include a review of graphene, methods to improve image recognition, streamlining electron density calculations, and optimizing protein studies.

Volcanic activity may have triggered the Black Death by spewing gases that led to crop failures in Europe, thus forcing the import of grain ships with plague-infested fleas.

Chaos theory—informally known as the butterfly effect—is the reason why weather forecasts are presented with probabilities rather than certainties.

Elk Cloner, the first computer virus to spread in public, was written as a practical joke by Richard Skrenta, a Pittsburgh high school student.

While the first exchange-traded fund (a 'basket' of different assets that can be bought and sold on a stock exchange) in the US only launched in 1993, the global ETF market has grown to more than $10T in the short time since.

A century of Billboard issues documenting the evolution of popular music.

Bone marrow (soft tissue found inside certain bones) generates roughly 500 billion new blood cells each day

Some Pokémon have been named after real and fictional organisms, while some real-world species have been named after Pokémon, such as Chilicola charizard and Binburrum zapdos.

How fusion—which releases energy when two lighter atoms combine to form a heavier atom—differs from fission

In 2026, Finland was named the world's happiest country for the ninth consecutive year based on its wealth, social safety network, and high life expectancy, among other factors.

Some researchers have labeled nomophobia, the fear of being without your phone, as 'the phobia of the 21st century.'

In 1945, Surrealist artist Salvador Dalí and legendary animator Walt Disney began collaborating on a short film that was not completed until 2003, years after both men had died.

The animatronic shark from Steven Spielberg's 'Jaws,' the first modern blockbuster, was a complex underwater apparatus called 'Bruce.'

During the French Revolution, a botanist's letter asking about "dear Rhus" (poison ivy) was intercepted, leading authorities to suspect he was conspiring with the Russians.