The flu shot looks different this year, thanks to the pandemic.
If you were one of the millions who masked up, washed your hands thoroughly and socially distanced, pat yourself on the back—you may have helped change the course of human history.
Scientists say that thanks to these safety precautions, which were introduced in early 2020 as a way to stop transmission of the novel COVID-19 virus, a strain of influenza has been completely eliminated. This marks the first time in human history that a virus has been wiped out through non-pharmaceutical interventions, such as vaccines.
The flu shot, explained
Influenza viruses type A and B are responsible for the majority of human illnesses and the flu season.
Centers for Disease Control
For more than a decade, flu shots have protected against two types of the influenza virus–type A and type B. While there are four different strains of influenza in existence (A, B, C, and D), only strains A, B, and C are capable of infecting humans, and only A and B cause pandemics. In other words, if you catch the flu during flu season, you’re most likely sick with flu type A or B.
Flu vaccines contain inactivated—or dead—influenza virus. These inactivated viruses can’t cause sickness in humans, but when administered as part of a vaccine, they teach a person’s immune system to recognize and kill those viruses when they’re encountered in the wild.
Each spring, a panel of experts gives a recommendation to the US Food and Drug Administration on which strains of each flu type to include in that year’s flu vaccine, depending on what surveillance data says is circulating and what they believe is likely to cause the most illness during the upcoming flu season. For the past decade, Americans have had access to vaccines that provide protection against two strains of influenza A and two lineages of influenza B, known as the Victoria lineage and the Yamagata lineage. But this year, the seasonal flu shot won’t include the Yamagata strain, because the Yamagata strain is no longer circulating among humans.
How Yamagata Disappeared
Flu surveillance data from the Global Initiative on Sharing All Influenza Data (GISAID) shows that the Yamagata lineage of flu type B has not been sequenced since April 2020.
Nature
Experts believe that the Yamagata lineage had already been in decline before the pandemic hit, likely because the strain was naturally less capable of infecting large numbers of people compared to the other strains. When the COVID-19 pandemic hit, the resulting safety precautions such as social distancing, isolating, hand-washing, and masking were enough to drive the virus into extinction completely.
Because the strain hasn’t been circulating since 2020, the FDA elected to remove the Yamagata strain from the seasonal flu vaccine. This will mark the first time since 2012 that the annual flu shot will be trivalent (three-component) rather than quadrivalent (four-component).
Should I still get the flu shot?
The flu shot will protect against fewer strains this year—but that doesn’t mean we should skip it. Influenza places a substantial health burden on the United States every year, responsible for hundreds of thousands of hospitalizations and tens of thousands of deaths. The flu shot has been shown to prevent millions of illnesses each year (more than six million during the 2022-2023 season). And while it’s still possible to catch the flu after getting the flu shot, studies show that people are far less likely to be hospitalized or die when they’re vaccinated.
Another unexpected benefit of dropping the Yamagata strain from the seasonal vaccine? This will possibly make production of the flu vaccine faster, and enable manufacturers to make more vaccines, helping countries who have a flu vaccine shortage and potentially saving millions more lives.
Living with someone changes your microbiome, new research shows
Some roommate frustration can be expected, whether it’s a sink piled high with crusty dishes or crumbs where a clean tabletop should be. Now, research suggests a less familiar issue: person-to-person transmission of shared bacterial strains in our gut and oral microbiomes. For the first time, the lab of Nicola Segata, a professor of genetics and computational biology at the University of Trento, located in Italy, has shown that bacteria of the microbiome are transmitted between many individuals, not just infants and their mothers, in ways that can’t be explained by their shared diet or geography.
It’s a finding with wide-ranging implications, yet frustratingly few predictable outcomes. Our microbiomes are an ever-growing and changing collection of helpful and harmful bacteria that we begin to accumulate the moment we’re born, but experts are still struggling to unravel why and how bacteria from one person’s gut or mouth become established in another person’s microbiome, as opposed to simply passing through.
“If we are looking at the overall species composition of the microbiome, then there is an effect of age of course, and many other factors,” Segata says. “But if we are looking at where our strains are coming from, 99 percent of them are only present in other people’s guts. They need to come from other guts.”
If we could better understand this process, we might be able to control and use it; perhaps hospital patients could avoid infections from other patients when their microbiome is depleted by antibiotics and their immune system is weakened, for example. But scientists are just beginning to link human microbiomes with various ailments. Growing evidence shows that our microbiomes steer our long-term health, impacting conditions like obesity, irritable bowel syndrome, type 2 diabetes, and cancer.
Previous work from Segata’s lab and others illuminated the ways bacteria are passed from mothers to infants during the first few months of life during vaginal birth, breastfeeding and other close contact. And scientists have long known that people in close proximity tend to share bacteria. But the factors related to that overlap, such as genetics and diet, were unclear, especially outside the mother-baby dyad.
“If we look at strain sharing between a mother and an infant at five years of age, for example, we cannot really tell which was due to transmission at birth and which is due to continued transmission because of contact,” Segata says. Experts hypothesized that they could be caused by bacterial similarities in the environment itself, genetics, or bacteria from shared foods that colonized the guts of people in close contact.
Strain sharing was highest in mother-child pairs, with 96 percent of them sharing strains, and only slightly lower in members of shared households, at 95 percent.
In Italy, researchers led by Mireia Valles-Colomer, including Segata, hoped to unravel this mystery. They compared data from 9,715 stool and saliva samples in 31 genomic datasets with existing metadata. Scientists zoomed in on variations in each bacterial strain down to the individual level. They examined not only mother-child pairs, but people living in the same household, adult twins, and people living in the same village in a level of detail that wasn’t possible before, due to its high cost and difficulties in retrieving data about interactions between individuals, Segata explained.
“This paper is, with high granularity, quantifying the percent sharing that you expect between different types of social interactions, controlling for things like genetics and diet,” Gibbons says. Strain sharing was highest in mother-child pairs, with 96 percent of them sharing strains, and only slightly lower in members of shared households, at 95 percent. And at least half of the mother-infant pairs shared 30 percent of their strains; the median was 12 percent among people in shared households. Yet, there was no sharing among eight percent of adult twins who lived separately, and 16 percent of people within villages who resided in different households. The results were published in Nature.
It’s not a regional phenomenon. Although the types of bacterial strains varied depending on whether people lived in western and eastern nations — datasets were drawn from 20 countries on five continents — the patterns of sharing were much the same. To establish these links, scientists focused on individual variations in shared bacterial strains, differences that create unique bacterial “fingerprints” in each person, while controlling for variables like diet, demonstrating that the bacteria had been transmitted between people and were not the result of environmental similarities.
The impact of this bacterial sharing isn’t clear, but shouldn’t be viewed with trepidation, according to Sean Gibbons, a microbiome scientist at the nonprofit Institute for Systems Biology.
“The vast majority of these bugs are actually either benign or beneficial to our health, and the fact that we're swapping and sharing them and that we can take someone else's strain and supplement or better diversify our own little garden is not necessarily a bad thing,” he says.
"There are hundreds of billions of dollars of investment capital moving into these microbiome therapeutic companies; bugs as drugs, so to speak,” says Sean Gibbons, a microbiome scientist at the Institute for Systems Biology.
Everyday habits like exercising and eating vegetables promote a healthy, balanced gut microbiome, which is linked to better metabolic and immune function, and fewer illnesses. While many people’s microbiomes contain bacteria like C. diff or E. coli, these bacteria don’t cause diseases in most cases because they’re present in low levels. But a microbiome that’s been wiped out by, say, antibiotics, may no longer keep these bacteria in check, allowing them to proliferate and make us sick.
“A big challenge in the microbiome field is being able to rationally predict whether, if you're exposed to a particular bug, it will stick in the context of your specific microbiome,” Gibbons says.
Gibbons predicts that explorations of microbe-based therapeutics will be “exploding” in the coming decades. “There are hundreds of billions of dollars of investment capital moving into these microbiome therapeutic companies; bugs as drugs, so to speak,” he says. Rather than taking a mass-marketed probiotic, a precise understanding of an individual’s microbiome could help target the introduction of just the right bacteria at just the right time to prevent or treat a particular illness.
Because the current study did not differentiate between different types of contact or relationships among household members sharing bacterial strains or determine the direction of transmission, Segata says his current project is examining children in daycare settings and tracking their microbiomes over time to understand the role genetics and everyday interactions play in the level of transmission that occurs.
This relatively newfound ability to trace bacterial variants to minute levels has unlocked the chance for scientists to untangle when and how bacteria leap from one microbiome to another. As researchers come to better understand the factors that permit a strain to establish itself within a microbiome, they could uncover new strategies to control these microbes, harnessing the makeup of each microbiome to help people to resist life-altering medical conditions.
Are the gains from gain-of-function research worth the risks?
Scientists have long argued that gain-of-function research, which can make viruses and other infectious agents more contagious or more deadly, was necessary to develop therapies and vaccines to counter the pathogens in case they were used for biological warfare. As the SARS-CoV-2 origins are being investigated, one prominent theory suggests it had leaked from a biolab that conducted gain-of-function research, causing a global pandemic that claimed nearly 6.9 million lives. Now some question the wisdom of engaging in this type of research, stating that the risks may far outweigh the benefits.
“Gain-of-function research means genetically changing a genome in a way that might enhance the biological function of its genes, such as its transmissibility or the range of hosts it can infect,” says George Church, professor of genetics at Harvard Medical School. This can occur through direct genetic manipulation as well as by encouraging mutations while growing successive generations of micro-organism in culture. “Some of these changes may impact pathogenesis in a way that is hard to anticipate in advance,” Church says.
In the wake of the global pandemic, the pros and cons of gain-of-function research are being fiercely debated. Some scientists say this type of research is vital for preventing future pandemics or for preparing for bioweapon attacks. Others consider it another disaster waiting to happen. The Government Accounting Office issued a report charging that a framework developed by the U.S. Department of Health & Human Services (HHS) provided inadequate oversight of this potentially deadly research. There’s a movement to stop it altogether. In January, the Viral Gain-of-Function Research Moratorium Act (S. 81) was introduced into the Senate to cease awarding federal research funding to institutions doing gain-of-function studies.
While testifying before the House COVID Origins Select Committee on March 8th, Robert Redfield, former director of the U.S. Centers for Disease Control and Prevention, said that COVID-19 may have resulted from an accidental lab leak involving gain-of-function research. Redfield said his conclusion is based upon the “rapid and high infectivity for human-to-human transmission, which then predicts the rapid evolution of new variants.”
“It is a very, very, very small subset of life science research that could potentially generate a potential pandemic pathogen,” said Gerald Parker, associate dean for Global One Health at Texas A&M University.
“In my opinion,” Redfield continues, “the COVID-19 pandemic presents a case study on the potential dangers of such research. While many believe that gain-of-function research is critical to get ahead of viruses by developing vaccines, in this case, I believe that was the exact opposite.” Consequently, Redfield called for a moratorium on gain-of-function research until there is consensus about the value of such risky science.
What constitutes risky?
The Federal Select Agent Program lists 68 specific infectious agents as risky because they are either very contagious or very deadly. In order to work with these 68 agents, scientists must register with the federal government. Meanwhile, research on deadly pathogens that aren’t easily transmitted, or pathogens that are quite contagious but not deadly, can be conducted without such oversight. “If you’re not working with select agents, you’re not required to register the research with the federal government,” says Gerald Parker, associate dean for Global One Health at Texas A&M University. But the 68-item list may not have everything that could possibly become dangerous or be engineered to be dangerous, thus escaping the government’s scrutiny—an issue that new regulations aim to address.
In January 2017, the White House Office of Science and Technology Policy (OSTP) issued additional guidance. It required federal departments and agencies to follow a series of steps when reviewing proposed research that could create, transfer, or use potential pandemic pathogens resulting from the enhancement of a pathogen’s transmissibility or virulence in humans.
In defining risky pathogens, OSTP included viruses that were likely to be highly transmissible and highly virulent, and thus very deadly. The Proposed Biosecurity Oversight Framework for the Future of Science, outlined in 2023, broadened the scope to require federal review of research “that is reasonably anticipated to enhance the transmissibility and/or virulence of any pathogen” likely to pose a threat to public health, health systems or national security. Those types of experiments also include the pathogens’ ability to evade vaccines or therapeutics, or diagnostic detection.
However, Parker says that dangers of generating a pandemic-level germ are tiny. “It is a very, very, very small subset of life science research that could potentially generate a potential pandemic pathogen.” Since gain-of-function guidelines were first issued in 2017, only three such research projects have met those requirements for HHS review. They aimed to study influenza and bird flu. Only two of those projects were funded, according to the NIH Office of Science Policy. For context, NIH funded approximately 11,000 of the 54,000 grant applications it received in 2022.
Guidelines governing gain-of-function research are being strengthened, but Church points out they aren’t ideal yet. “They need to be much clearer about penalties and avoiding positive uses before they would be enforceable.”
What do we gain from gain-of-function research?
The most commonly cited reason to conduct gain-of-function research is for biodefense—the government’s ability to deal with organisms that may pose threats to public health.
In the era of mRNA vaccines, the advance preparedness argument may be even less relevant.
“The need to work with potentially dangerous viruses is central to our preparedness,” Parker says. “It’s essential that we know and understand the basic biology, microbiology, etc. of some of these dangerous pathogens.” That includes increasing our knowledge of the molecular mechanisms by which a virus could become a sustained threat to humans. “Knowing that could help us detect [risks] earlier,” Parker says—and could make it possible to have medical countermeasures, like vaccines and therapeutics, ready.
Most vaccines, however, aren’t affected by this type of research. Essentially, scientists hope they will never need to use it. Moreover, Paul Mango, HSS former deputy chief of staff for policy, and author of the 2022 book Warp Speed, says he believes that in the era of mRNA vaccines, the advance preparedness argument may be even less relevant. “That’s because these vaccines can be developed and produced in less than 12 months, unlike traditional vaccines that require years of development,” he says.
Can better oversight guarantee safety?
Another situation, which Parker calls unnecessarily dangerous, is when regulatory bodies cannot verify that the appropriate biosafety and biosecurity controls are in place.
Gain-of-function studies, Parker points out, are conducted at the basic research level, and they’re performed in high-containment labs. “As long as all the processes, procedures and protocols are followed and there’s appropriate oversight at the institutional and scientific level, it can be conducted safely.”
Globally, there are 69 Biosafety Level 4 (BSL4) labs operating, under construction or being planned, according to recent research from King’s College London and George Mason University for Global BioLabs. Eleven of these 18 high-containment facilities that are planned or under construction are in Asia. Overall, three-quarters of the BSL4 labs are in cities, increasing public health risks if leaks occur.
Researchers say they are confident in the oversight system for BSL4 labs within the U.S. They are less confident in international labs. Global BioLabs’ report concurs. It gives the highest scores for biosafety to industrialized nations, led by France, Australia, Canada, the U.S. and Japan, and the lowest scores to Saudi Arabia, India and some developing African nations. Scores for biosecurity followed similar patterns.
“There are no harmonized international biosafety and biosecurity standards,” Parker notes. That issue has been discussed for at least a decade. Now, in the wake of SARS and the COVID-19 pandemic, scientists and regulators are likely to push for unified oversight standards. “It’s time we got serious about international harmonization of biosafety and biosecurity standards and guidelines,” Parker says. New guidelines are being worked on. The National Science Advisory Board for Biosecurity (NSABB) outlined its proposed recommendations in the document titled Proposed Biosecurity Oversight Framework for the Future of Science.
The debates about whether gain-of-function research is useful or poses unnecessary risks to humanity are likely to rage on for a while. The public too has a voice in this debate and should weigh in by communicating with their representatives in government, or by partaking in educational forums or initiatives offered by universities and other institutions. In the meantime, scientists should focus on improving the research regulations, Parker notes. “We need to continue to look for lessons learned and for gaps in our oversight system,” he says. “That’s what we need to do right now.”