TIME Infectious Disease

Pregnant Women and the Flu: Why Influenza Is More Dangerous for Expectant Moms

Immune responses are enhanced during pregnancy, study finds

Only 50% of pregnant women get the flu vaccine, but they’re among the most vulnerable to influenza. When mothers-to-be catch the virus, they tend to get much sicker than other healthy adults, and it increases their risk for delivering prematurely.

A new Stanford University study published in the Proceedings of the National Academy of Sciences looked at why pregnant women are so susceptible to the flu, and they found the culprit may be over-zealous cells that are key to fighting off infection.

Researchers collected immune cells from about 50 women, half of whom were pregnant and half who weren’t. They then infected the cell samples with influenza virus in a lab. In the samples from the pregnant women, two types of white blood cells, called natural killer and T cells, had enhanced immune responses, causing them to attract even more immune cells to help fight the virus.

While it might seem that such a strong response to the flu is exactly what expectant mothers would want, it can be too much of a good thing, says Dr. Catherine Blish, assistant professor of infectious diseases at Stanford School of Medicine and the study’s senior author. “Having too many immune cells in the lung can cause inflammation that makes it hard to breathe,” she says, which might help explain why pregnant women who get the flu are at greater risk for pneumonia and death. “If these findings are confirmed in bigger studies and then natural infection, they could explain why pregnant women do so poorly.”

“We normally think that these particular cells are suppressed by pregnancy to protect the fetus—it’s what we all learned in medical school,” Blish says. “And we found when we used a generalized stimulation that that was the case. But there’s something specific about flu that leads to this enhanced response.”

Getting the flu vaccine helps protect pregnant women, Blish says, and she and her team “really strongly recommend” that all women who are pregnant or considering getting pregnant get vaccinated.

Blish and her colleagues plan to study whether other viruses have the same effect and whether it’s possible to treat severe influenza by turning down this immune response. But even if these findings eventually lead to new therapies, she says, “the most important thing to remember is that influenza vaccine is really the best tool to prevent infection in the first place.”

TIME Infectious Disease

Health Experts Urge Flu Vaccination

Pregnant women and children are particularly vulnerable

“We can’t predict what this year’s flu season will be like,” said Centers for Disease Control and Prevention (CDC) Director Tom Frieden at a National Foundation for Infectious Diseases press conference Thursday. “But we can predict that the best way to protect yourself against the flu is to get a flu vaccination.”

More than 90 percent of doctors and nurses receive a flu vaccination, experts said. They stressed that pregnant women and children are particularly vulnerable and should prioritize taking the vaccine. Flu-related complications can lead to early labor in pregnant women, said Laura Riley, director of labor and delivery at Massachusetts General Hospital.

A lack of understanding of the risks of the and a belief in “scientifically unfounded views” were the most common reasons people decided against taking the vaccine, according to Children’s Hospital of Philadelphia infectious disease expert Paul A. Offit.

“The riskiest thing about vaccines is driving to the office to get them,” he said.

Last year 10 million people in the United States caught the flu, causing thousands of deaths. More than 100 children died, 90 percent of whom didn’t take a flu shot.

TIME Infectious Disease

Hand Sanitizers Don’t Lower School Absences

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A new study shows hand sanitizer doesn't keep kids in school Paul Velgos—Getty Images

Putting hand sanitizers in schools and encouraging kids to use them doesn’t lower the rate of school absences, according to new research published Tuesday in the journal PLOS Medicine.

“These findings suggest that in high-income countries, where clean water for hand washing is readily available, putting resources into extra hand hygiene by providing hand sanitizer in classrooms may not be an effective way to break the child-to-child transmission of infectious diseases,” the study authors conclude.

The team of New Zealand researchers randomly assigned 68 primary schools to either have alcohol-based hand sanitizers in the classroom or not. All of the students in the participating schools underwent a 30 minute session on hand hygiene. The kids were also told that they should use the hand sanitizer after they coughed or sneezed, as well as when they left the classroom.

Despite the high level of encouraged use of the dispensers, the researchers found that there was no difference in the rates of school absences between the schools with dispensers and the schools without. Still, the study had some limitations. During the study period, there was an flu going around in the region—which means that the population was likely hearing public health messages about flu prevention in other places, making the effectiveness of their specific intervention difficult to parse.

For now, a good bar or soap and water, for those lucky enough to use them liberally, should do the trick.

 

TIME

Nasal Flu Spray Better Than Shot For Young Kids, CDC Panel Says

Kids who use the nasal flu vaccine are half as likely to get sick as those who get the shot

Needle-phobic kids, rejoice!

U.S. health officials say the nasal spray flu vaccine is more effective than a traditional shot for children ages 2 to 8.

The Advisory Committee on Immunization Practices, a group of experts that makes recommendations to the Centers for Disease Control for which vaccines children and adults should get, voted to recommend the spray over the shot late Wednesday. The panel said studies show children who had the spray are half as likely to get the flu as those who had the shot.

So far, there is only one nasal spray flu vaccine available — AstraZeneca’s FluMist, which was approved in 2003 for people ages 2 to 49.

The spray differs from the needle-based vaccine in another important way — it’s made from a live, weakened influenza virus, while the shot drums up an immune response using killed virus. Studies have shown the spray can lead to a stronger immune response in children who have not had the flu before, but the same may not hold true for adults.

Not everyone agrees with the panel’s recommendation, however. The American Academy of Pediatrics, the nation’s largest pediatric group, does not think any one vaccine should be given preference for kids, since both are effective. One concern they cite is the fact that FluMist is typically more expensive than the flu shot, according to the Associated Press. AstraZeneca’s product costs about $23 while shots range from $8 to $22.

Other experts say that the spray isn’t for everyone. “Some kids can’t take the mist, namely those with compromised immune systems and kids with asthma, who could have a respiratory response,” Marc Siegel, an associate professor of medicine at NYU Langone Medical Center in New York City, told HealthDay. “So when in doubt, get the shot.”

The committee’s advice, which government pubic health officials usually follow, also comes too late for the upcoming flu season in the fall. Doctors have already ordered their vaccine doses, so if approved, most pediatricians won’t be able to follow the advice until next year.

Still, according to the AP, AstraZeneca may have anticipated the decision and made more of the spray for the coming flu season. The company will manufacture 18 million doses to distribute globally, up from 13 million made for the U.S. last year, Kathleen Coelingh, the company’s senior director of U.S. medical affairs told the news agency.

While not everyone agrees on the panel’s advice, public health experts do agree on the fact that every child should be immunized. If the nasal spray is not immediately available, children should get the flu shot so that they do not miss or delay an opportunity to get vaccinated.

 

TIME health

The Medieval Black Death Made You Healthier—If You Survived

Plague killed millions in Europe
The Black Death killed as much as half of Europe's population Photo by Science & Society Picture Library/SSPL/Getty Images

The plague was horrific, could hit without warning and killed tens of millions in 14th century Europe. But paradoxically, the population that survived ended up better off, with higher wages, cleaner living conditions and healthier food

Game of Thrones doesn’t tell you the half of it. Life during the medieval ages was nasty, brutish and short. That was especially true during what became known as the Black Death. The widespread outbreak of plague struck between 1347 and 1351, killing tens of millions of people, resulting in the loss of 30 to 50% of the region’s population. The disease itself was horrific. “In men and women alive,” wrote the Italian poet Giovanni Boccaccio, “at the beginning of the malady, certain swellings, either on the groin or under the armpits…waxed to the bigness of a common apple, others to the size of an egg, some more and some less, and these the vulgar named plague-boils.” And it seemed to strike indiscriminately and without warning. People could be healthy in the morning and dead by evening.

The upside, if you can call it that, is that the plaque left in its wake populations that were healthier and more robust than people who existed before the plague struck, according to a new study published today in PLOS ONE. “The Black Death was a selective killer,” says Sharon DeWitte, a biological anthropologist at the University of South Carolina and the author of the paper. “And after the Black Death ended, there was actually an improvement in the standard of living.” The plague was natural selection in action.

In a way, that’s a marker of how brutal the medieval era was. It took a serial killer of a plague to actually bring about an improvement in living conditions. If that sounds counterintuitive, think about how life might have changed after half of Europe’s population died off. Suddenly there was a dramatic drop in the number of able-bodied adults available to do work, which meant survivors could charge more for their labor. At the same time, fewer people meant a decreased demand for foods, goods and housing—and as a result, the prices for all three dropped. By the late 15th century, real wages were three times higher than they were at the beginning of the 14th century, before the plague struck. Diets improved as employers were forced to raise wages and offer extra food and clothing to attract workers. As a result, the money spent per capita on food in the wake of the Black Death actually increased. “People were able to eat more meat and high-quality bread, which in turn would have improved health,” says DeWitte.

But the clearest evidence that people were healthier after the Black Death than they were before it comes in the bodies themselves. DeWitte looked at skeletal samples taken from medieval cemeteries in London both before the plague and after it. She found that post-Black Death samples had a higher proportion of older adults, and that morality risks were generally lower in the post-Black Death population than before the epidemic. In other words, if you were strong and lucky enough to survive one of the deadliest epidemics in human history, you were probably strong enough to live to a relatively ripe old age. And since the Black Death was so widespread, that was true for the surviving population as a whole.

Earlier studies looking at historical documents like diaries, letters and wills from the time period had shown conflicting results, but that kind of data only covers the very small part of the population that was literate, male and relatively well off. The advantage of DeWitte’s grave-combing bioarchaeological research methods is that they encompass a much more representative swath of the medieval population. “This provides information about the people who are missing from historical documents, including women and children,” says DeWitte. Not everyone in medieval London left a will behind—but everyone left a corpse.

So for survivors, life after the Black Death would have been at least a little less nasty, brutish and short than life before it. But that doesn’t mean the survivors were really the lucky ones. The Black Death was a period of unremitting horror and terror, the likes of which we can’t imagine. No one knew how the disease spread, or how to treat it. Popular but gruesome methods like blood-letting or boil-lancing would have been counterproductive at best, assuming victims could find anyone to treat them. Doctors abandoned their patients for fear of infection, and priests even refused to give last rites to the dying—an appalling dereliction given medieval fears of eternal damnation. Even animals like sheep, cows and pigs fell victim to the disease. “The people who survived the Black Death would have lost everyone they knew,” says DeWitte. “They’re the people I feel sorry for.” If the Black Death really was natural selection at work, it was the cruelest form imaginable.

TIME health

Solving the Mystery Flu That Killed 50 Million People

The deadly 1918 flu pandemic
The 1918 flu pandemic killed an estimated 50 million people Photo Researchers via Getty Images

Researchers have wondered for decades why the 1918 flu disproportionately killed so many young people, but a new study in the Proceedings of the National Academy of Sciences suggests the answers are in the pattern of past flu infections

Years ago the environmental historian Alfred Crosby was at Washington State University, where he was teaching at the time, when on a whim he decided to pick up an old almanac from 1917. (This is apparently the kind of thing historians like to do in their spare time.) He looked up the U.S. life expectancy in that year—it was about 51 years. He turned to the 1919 almanac, and found about the same figure. Then Crosby picked up the almanac from 1918. The U.S. life expectancy in 1918 had fallen to 39 years. “What the hell happened?” Crosby told the New York Times writer Gina Kolata in her book Flu: The Story of the Great Influenza Pandemic of 1918. “ The life expectancy had dropped to what it had been fifty years before.”

What happened was the 1918 influenza pandemic. A virus that usually does little more than make people feel awful for a few days killed an estimated 50 million people worldwide, if not far more, with 650,000 people dying in the U.S. alone. The flu killed more people in a year than the bubonic plague killed in a century in the Middle Ages. Worst of all, this flu disproportionately took the lives of men and women in their 20s and 30s, while often sparing the very old and the very young—two population groups that are especially vulnerable to the flu in most years.

This has confounded scientists for almost a century, but a new study in the Proceedings of the National Academy of Sciences (PNAS) puts forward a fresh answer to one of the enduring mysteries of medical science. Researchers led by Michael Worobey of the University of Arizona reconstructed the origins of the 1918 pandemic, concluding that the pathogen arose when an existing human H1 flu virus acquired genetic material from a bird flu virus. That new H1N1 flu virus was able to evade immune systems, which helps explain why it infected more than a quarter of the U.S. population at the time. But it was young adults between the ages of 20 and 40 that died in the greatest number—and Worobey’s study suggests that the unusual death pattern was due as much to flus of the past as it was to the flu of 1918. “Prior immunity, or lack of it, seems to be the decisive factor,” says Worobey.

Flu viruses are constantly changing and mutating, which is why we can’t develop a lifelong vaccine for it the way we can for more stable viruses, like the ones that cause smallpox or the measles. A flu virus has two parts: hemagglutinin and neuraminidase proteins, shortened to HA and NA (and just H and N when naming a virus). It’s the HA protein that seems to drive our immune system response, as Worobey put it in a statement:

Imagine a soccer ball studded with lollipops. The candy part of the lollipop is the globular part of the HA protein, and that is by far the most potent part of the flu virus against which our immune system can make antibodies. If antibodies cover all the lollipop heads, the virus can’t even infect you.

Worobey and his colleagues looked back at the kinds of flu viruses that were in circulation in the decades preceding the 1918 pandemic by examining antibodies found in old blood samples. (Your immune system will produce customized antibodies in response to a flu infection, and those antibodies will remain in your body, which allows scientists to identify the genetic makeup of the virus that led to their creation.) It turns out people born between 1880 and 1900—the generation hit hardest by the 1918 flu—were mostly exposed during childhood to a H3N8 flu virus that began circulating during an earlier pandemic in 1889, but not to an H1 virus, which meant that generation had virtually no antibodies to fight it off.

By reconstructing the genetic origins of the 1918 flu, Worobey found that a version of that H1N1 flu virus was circulating for years before the pandemic began. Because flu strikes most commonly in childhood, those born after 1900 were more likely to have had previous exposure to an H1N1-like flu virus, which would have offered them some protection. Meanwhile those born before 1880 were more likely to have been exposed to the H1N8 flu strain that was prevalent when they were children. In both the very young and the old, having earlier exposure to an H1 flu—even one different from the strain that caused the 1918 pandemic—offered a level of protection not present in those who had never been infected by an H1 strain. That could explain the unusual mortality curve in the 1918 pandemic.

1918 flu mortality curve
The researchers found a remarkable overlap between death rates in various age groups in 1918 and childhood exposure to an H3 flu virus that was mismatched with H1N1 pandemic virus. Credit: Michael Worobey

Thankfully, no flu pandemic since 1918 has been anywhere near as deadly. The 2009 swine flu pandemic killed an estimated 284,000 people worldwide, comparable to flu deaths in a non-pandemic year. But two avian flu viruses — H5N1 and H7N9 — have for years been periodically jumping the species barrier and infecting human beings. And like the 1918 flu, H5N1 and H7N9 are unusually deadly, particularly for the young and elderly, respectively. “Lots of different age groups might be exposed to these viruses, but the virus that kills them is the one that’s mismatched to the virus they encountered as a child,” says Worobey.

The PNAS paper suggests that this might be due to past flu patterns as well, with both groups having been exposed to flu viruses in their youth that offered them little protection against the new pathogens. If either virus were to mutate to the point where it could spread easily in the human population, the results could be catastrophic.

But the PNAS paper offers hope that doctors could begin to design flu vaccination strategies that compensate for the strains that different age groups never experienced as children. Down the line, scientists may even be able to develop a universal flu vaccine that targets parts of the virus that almost never change from strain to strain. “This work is encouraging that possibility,” says Worobey. If we’re smart, the global catastrophe that was the 1918 pandemic will remain confined to the history books.

TIME Exercise

The Workouts That Can Prevent The Flu

Study: Workouts Prevent Flu
Keith Bishop—Getty Images

Vigorous exercise is better than moderate exercise at boosting the immune system.

You know that vigorous exercise burns fat and builds muscle (and it may even help fight cravings)—and now you might be able to add “fight the flu” to its list of accomplishments, according to research recently released at National Science and Engineering Week.

Through an online survey, researchers at the London School of Hygiene and Tropical Medicine polled more than 4,800 people on their health habits and found that those who exercised vigorously for at least two and a half hours a week were about 10 percent less likely to come down with a flu-like illness. Meanwhile, moderate exercise didn’t seem to have any effect on the flu.

While all exercise is known to increase immunity, previous research in the European Journal of Preventative Cardiology shows that high-intensity exercise is better than moderate exercise at improving the body’s aerobic capacity, a marker of overall health and fitness. And the fitter you are, the more likely your immune system will be able to wipe out nasty cells like the flu bug.

Cold or Flu: Can you Tell

However, it’s important to remember that overdoing it on high-intensity exercise can actually wear down the immune system, per a 2014 study in the Journal of Strength & Conditioning Research. Luckily, two and a half hours of high-intensity exercise a week is all your need to reap the flu-fighting benefits of hardcore exercise.

Think you’ve already beaten this year’s flu? Not so fast. While we are nearing the end of the season, the nasty bug can strike any time of year, note the researchers.

So for good measure, we’ve rounded up 10 of our favorite high intensity workouts. Try them out, and fight the flu and weight gain at the same time!

30-Minute Workout: Get Total-Body Toned with this No-Equipment Circuit Workout

This article was written by K. Aleisha Fetters and originally appeared on Womenshealthmag.com.

 

TIME Research

Study Finds Tamiflu Not as Effective as Thought

The antiviral drug isn’t any better than other treatments for the flu, leading experts to question why countries stockpile the medication

Researchers say the popular antiviral flu drugs Tamiflu and Relenza are not as effective as doctors and public health experts were led to believe, in the most comprehensive review of data on the effectiveness of the two drugs.

There isn’t strong evidence to support stockpiling the products in national emergency drug depots in case of a pandemic, the researchers say. Both drugs—Tamiflu is the brand name for oseltamivir and Relenza is the brand name zanamivir—are designed to stop the influenza virus from spreading in an infected person, and claim to reduce the severity of flu symptoms and how long people are sick. The Centers for Disease Control and Prevention keeps the drugs in its stockpile for use in both seasonal and pandemic flu situations, and the European Medicines Agency (EMA) and the World Health Organization also recommend the medications for treating flu.

MORE: Scientists Can Now Predict the Flu

The authors of the current review found, however, that in the case of the European approvals in particular, regulatory agencies relied on summaries of studies rather than an exhaustive analysis of raw data, known as clinical study reports, which can run to more than 1,000 pages and detail methods, protocols and statistical analyses.

After a four-year effort to obtain this data from both the manufacturers and the EMA, the authors report in the journal BMJ that those trials do not support claims that the drugs lower the risk of complications from flu, such as pneumonia, or that the benefits of the drugs outweigh their risks, which include nausea, vomiting, headaches and kidney disorders.

The authors point to not just one failure in the process of approving these medications, but a weak regulatory system in which the studies are all conducted by manufacturers, and in which the trials compared the medications against placebo rather than to existing flu treatments.

Given that the more comprehensive review found little support for recommending oseltamivir to reduce flu symptoms or hospitalization due to complications from flu, the authors write: “We believe these findings provide reason to question the stockpiling of oseltamivir, its inclusion on the WHO list of essential drugs, and its use in clinical practice as an anti-influenza drug.” On zanamivir, they said “Our findings do not support the mode of action of zanamivir proposed by the manufacturer.”

TIME big data

Google’s Flu Project Shows the Failings of Big Data

Google flu trends
GEORGES GOBET/AFP/Getty Images

A new study shows that using big data to predict the future isn't as easy as it looks—and that raises questions about how Internet companies gather and use information

Big data: as buzzwords go, it’s inescapable. Gigantic corporations like SAS and IBM tout their big data analytics, while experts promise that big data—our exponentially growing ability to collect and analyze information about anything at all—will transform everything from business to sports to cooking. Big data was—no surprise—one of the major themes coming out of this month’s SXSW Interactive conference. It’s inescapable.

One of the most conspicuous examples of big data in action is Google’s data-aggregating tool Google Flu Trends (GFT). The program is designed to provide real-time monitoring of flu cases around the world based on Google searches that match terms for flu-related activity. Here’s how Google explains it:

We have found a close relationship between how many people search for flu-related topics and how many people actually have flu symptoms. Of course, not every person who searches for “flu” is actually sick, but a pattern emerges when all the flu-related search queries are added together. We compared our query counts with traditional flu surveillance systems and found that many search queries tend to be popular exactly when flu season is happening. By counting how often we see these search queries, we can estimate how much flu is circulating in different countries and regions around the world.

Seems like a perfect use of the 500 million plus Google searches made each day. There’s a reason GFT became the symbol of big data in action, in books like Kenneth Cukier and Viktor Mayer-Schonberger’s Big Data: A Revolution That Will Transform How We Live, Work and Think. But there’s just one problem: as a new article in Science shows, when you compare its results to the real world, GFT doesn’t really work.

GFT overestimated the prevalence of flu in the 2012-2013 and 2011-2012 seasons by more than 50%. From August 2011 to September 2013, GFT over-predicted the prevalence of the flu in 100 out 108 weeks. During the peak flu season last winter, GFT would have had us believe that 11% of the U.S. had influenza, nearly double the CDC numbers of 6%. If you wanted to project current flu prevalence, you would have done much better basing your models off of 3-week-old data on cases from the CDC than you would have been using GFT’s sophisticated big data methods. “It’s a Dewey beats Truman moment for big data,” says David Lazer, a professor of computer science and politics at Northeastern University and one of the authors of the Science article.

Just as the editors of the Chicago Tribune believed it could predict the winner of the close 1948 Presidential election—they were wrong—Google believed that its big data methods alone were capable of producing a more accurate picture of real-time flu trends than old methods of prediction from past data. That’s a form of “automated arrogance,” or big data hubris, and it can be seen in a lot of the hype around big data today. Just because companies like Google can amass an astounding amount of information about the world doesn’t mean they’re always capable of processing that information to produce an accurate picture of what’s going on—especially if turns out they’re gathering the wrong information. Not only did the search terms picked by GFT often not reflect incidences of actual illness—thus repeatedly overestimating just how sick the American public was—it also completely missed unexpected events like the nonseasonal 2009 H1N1-A flu pandemic. “A number of associations in the model were really problematic,” says Lazer. “It was doomed to fail.”

Nor did help that GFT was dependent on Google’s top-secret and always changing search algorithm. Google modifies its search algorithm to provide more accurate results, but also to increase advertising revenue. Recommended searches, based on what other users have searched, can throw off the results for flu trends. While GFT assumes that the relative search volume for different flu terms is based in reality—the more of us are sick, the more of us will search for info about flu as we sniffle above our keyboards—in fact Google itself alters search behavior through that ever-shifting algorithim. If the data isn’t reflecting the world, how can it predict what will happen?

GFT and other big data methods can be useful, but only if they’re paired with what the Science researchers call “small data”—traditional forms of information collection. Put the two together, and you can get an excellent model of the world as it actually is. Of course, if big data is really just one tool of many, not an all-purpose path to omniscience, that would puncture the hype just a bit. You won’t get a SXSW panel with that kind of modesty.

A bigger concern, though, is that much of the data being gathered in “big data”—and the formulas used to analyze it—is controlled by private companies that can be positively opaque. Google has never made the search terms used in GFT public, and there’s no way for researchers to replicate how GFT works. There’s Google Correlate, which allows anyone to find search patterns that purport to map real-life trends, but as the Science researchers wryly note: “Clicking the link titled ‘match the pattern of actual flu actvity (this is how we built Google Flu Trends!)’ will not, ironically, produce a replication of the GFT search terms.” Even in the academic papers on GFT written by Google researchers, there’s no clear contact information, other than a generic Google email address. (Academic papers almost always contain direct contact information for lead authors.)

At its best, science is an open, cooperative and cumulative effort. If companies like Google keep their big data to themselves, they’ll miss out on the chance to improve their models, and make big data worthy of the hype. “To harness the research community, they need to be more transparent,” says Lazer. “The models for collaboration around big data haven’t been built.” It’s scary enough to think that private companies are gathering endless amounts of data on us. It’d be even worse if the conclusions they reach from that data aren’t even right.

TIME flu

Scientists Can Now Predict the Flu

Girl in bed with thermometer in mouth
Girl in bed with thermometer in mouth Getty Images

A mathematical model could make future seasons' vaccines more accurate

Researchers have figured out a formula that can predict the evolution of the seasonal flu for the next year.

In a study published in the journal Nature, researchers from Columbia University and the University of Cologne looked at the way the common H3N2 flu virus mutated and changed throughout the years since 1968. Based off that data, they created a mathematical model that accurately predicts how the virus will change in the future.

The seasonal H3N2 influenza accounts for about half a million deaths every year. To determine what flu strains should be included in the vaccine each year, health experts study the virus, how it changes, and its frequency. The prediction model that researchers have now come up with is significant because it could make the shot you get every season even more accurate, and thus flu-resistant.

To create their model, the researchers looked at the viruses circulating in a given season and its genomes, as well as how many people those viruses infected. Some of the viruses’ adaptive mutations, which occur in what is called the haemagglutinin protein of a virus, were shown to increase the virus’ life and growth, whereas others crippled it.

By examining every strain of the virus through the decades, the study’s authors formulated an equation. More weight was given to mutations that were likely to boost the virus, and the strain’s strength was determined by factoring in its growth rate. When researchers went back and compared their estimates to various years, they found their formula to be highly accurate.

The results of the study have to be replicated before they can begin to be applied to our real-world seasonal vaccines, but the study’s authors say they hope that a more precise prediction method could lead to a highly protective vaccine. And, likely, so does anyone crippled by the flu this season.

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