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Tag: measles vaccine

  • Why the measles, mumps and rubella vaccine is combined

    President Donald Trump wants the combined MMR vaccine that protects against measles, mumps and rubella, broken up into separate shots. 

    Individual vaccines against measles, mumps and rubella are not currently available in the United States. The U.S. Centers for Disease Control and Prevention’s acting director called for manufacturers to develop separate shots and Health and Human Services Secretary Robert F. Kennedy Jr. said officials are evaluating the feasibility of separating the vaccines.

    The MMR vaccine has been combined since 1971, and it would take years for separate vaccines to be tested and licensed in the U.S.

    Trump’s repeated calls to “break up the MMR shot” and “take them separately” might have Americans wondering whether they can get separate shots and how and why the vaccines were ever combined. Here are some answers to common MMR vaccine questions. 

    Q: Why is the MMR vaccine combined, anyway? 

    A: Public health officials wanted to make it easier for people to get vaccinated, because that increases overall vaccination rates and decreases cases of these diseases. 

    Measles, mumps and rubella vaccines were good candidates for combination because they were typically given on the same schedule. Combining them meant fewer doctor’s visits and fewer needles in arms, which can be stressful for kids and parents. 

    Combining the vaccines was also possible because all three rely on weakened versions of the viruses to trigger immune responses that teach the body to fight the live viruses, said Dr. Walter Orenstein, an epidemiologist who directed the U.S. Immunization Program from 1998 to 2004.

    These vaccines had similar ingredients and manufacturing processes, which made it possible to combine them, Orenstein said.

    Scientists rigorously tested whether these vaccines could safely and effectively be combined without reducing the immune responses to each individual illness.

    The MMR vaccine is administered in two doses and given to children first at 12 to 15 months old and then between ages 4 and 6. Getting your child fully vaccinated against these three diseases requires two visits to your pediatrician’s office and two shots.

    If the MMR vaccine were split up and you wanted to get your child vaccinated at separate medical appointments — something Trump has also advised — it could take six visits. That means scheduling six appointments, paying for six doctor visits and your child receiving six injections. 

    When it is difficult to get fully vaccinated, fewer people do it. 

    “If you’re separating the vaccine, there’s an inconvenience,” said Dr. Amesh Adalja, an infectious disease expert at the Johns Hopkins Center for Health Security. “It’s also more likely that one or more of those vaccines slips through the cracks.”

    Q: Does any science support separating the MMR vaccine? 

    A: No. 

    “There is no published scientific evidence showing any benefit in separating the combination MMR vaccine,” Johns Hopkins Bloomberg School of Public Health posted Oct. 8 on Facebook. Other vaccine experts echoed this sentiment. 

    The White House provided no studies or reports that support separating the MMR vaccine into three vaccines. 

    Vials of the MMR measles mumps and rubella virus vaccine sit in a refrigerator with other medicine Feb. 25, 2025, in Lubbock, Texas. (AP)

     

    Q: Are other vaccines combined? 

    A: Yes. The DTaP vaccine series protects against diphtheria, tetanus and pertussis or whooping cough. Like the MMR vaccine, separate vaccines aren’t available in the U.S. for diphtheria, tetanus and pertussis. 

    The Pediarix vaccine protects against diphtheria, tetanus, pertussis, hepatitis B and polio and the Pentacel vaccine protects against diphtheria, tetanus, polio and Haemophilus influenzae type b or Hib. 

    Q: If combination vaccines are intended to improve convenience, why aren’t all vaccines combined? 

    A: In a perfect world, all the vaccine protection a person needs could be delivered in one combined shot, Adalja said. 

    That’s not possible because physicians administer vaccines when the protection will be most valuable. 

    “The vaccine schedule is not created arbitrarily,” he said. “There’s different times (of life) when you might be exposed to something, different times when the risk for severe disease is higher.”

    It’s also impossible to combine certain vaccines.

    Some ingredients in inactivated vaccines — or vaccines that use a killed version of a germ to prompt immune response — could kill the weakened live viruses used in the measles, mumps and rubella vaccines, Orenstein said. 

    Lead medical assistant Maria Teresa Diocales administers the measles, mumps and rubella (MMR) vaccine to 1-year-old at International Community Health Services, Sept. 10, 2025, in Seattle. (AP)

    Q: Do separate MMR vaccines exist anywhere? 

    A: No country’s government recommends using three separate vaccines to protect against measles, mumps and rubella, but separate vaccines are available in some countries for use in certain circumstances, according to the United Kingdom government. 

    In France, infants 6 months to 11 months can be given a separate measles vaccine if necessary following an exposure to measles or ahead of plans to travel somewhere with high numbers of measles cases. After that, however, French public health experts still recommend children receive a combined MMR vaccination following the vaccine schedule.  

    Japan recommends a combined measles and rubella vaccine and does not routinely vaccinate against mumps, but a separate mumps vaccine is available. 

    Q: Can separate vaccines be tested and licensed for use in the U.S.? 

    A: If it could be done at all, it would likely take years to accomplish, experts said. 

    “It would depend upon what regulatory requirements the (Food and Drug Administration) placed on the company in order to prove safety and efficacy of that vaccine,” Adalja said. 

    In May, a Department of Health and Human Services spokesperson told The Washington Post that all new vaccines would be required to “undergo safety testing in placebo-controlled trials prior to licensure.” 

    That raises ethical issues when it comes to clinical testing of individual vaccines against measles, mumps and rubella. 

    Oversight boards that review and approve clinical trials would not approve trials with placebo groups for measles, mumps and rubella because an existing vaccine is effective, said Angela Rasmussen, a virologist at the University of Saskatchewan. 

    Exposing children to potentially deadly illnesses is unethical, she said. 

    There’s also no guarantee that vaccine manufacturers would even attempt to separate the vaccines. 

    “Vaccines are not very lucrative, and they’re becoming less and less lucrative based on the environment that we have in the United States,” Adalja said. 

    Merck and GSK manufacture combined MMR vaccines used in the U.S. GSK did not respond to PolitiFact’s questions about whether they will respond to the administration’s calls to separate the MMR vaccine.

    In a statement to PolitiFact, Merck said splitting the MMR vaccine would essentially involve creating three new, experimental and separately licensed vaccines, each requiring full clinical testing and regulatory review. 

    “We estimate that, in total, it could take more than 10 years before Merck could obtain FDA approvals and begin manufacturing and commercialization,” the company said.

    A sign is seen outside a clinic with the South Plains Public Health District, Feb. 23, 2025, in Brownfield, Texas. (AP)

    Q: What would happen if the combined MMR vaccine were no longer offered in the U.S.?

    A: The most immediate effect would be that vaccination would stop because there is no alternative. But even if separate measles, mumps and rubella vaccines were eventually tested, approved and available, vaccine uptake likely would drop because getting vaccinated would require more effort, Rasmussen said. 

    Either way, that would mean more cases of measles, rubella and mumps. 

    “We will see more longer term impacts too,” she said. That might include increased infertility from mumps, increased disability from measles and congenital rubella syndrome, more stillbirths and miscarriages from rubella and more cases of SSPE, a progressive brain disorder that stems from measles infection. 

    Replacing the MMR vaccine with separate vaccines “is a preventable tragedy and terrible mistake for public health,” Rasmussen said. 

    Editor’s note: Google Translate was used throughout the research of this story to translate websites and statements into English.

    RELATED: How do countries without school vaccination requirements maintain high vaccination rates?

    RELATED: Why is metal used in vaccines? Is it safe? Here’s what to know about aluminum in vaccines. 

    RELATED: Hepatitis B vaccine Q&A: Why do babies need the shot?

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  • The Other Group of Viruses That Could Cause the Next Pandemic

    The Other Group of Viruses That Could Cause the Next Pandemic

    Whether it begins next week, next year, or next decade, another pandemic is on its way. Researchers can’t predict precisely when or how the outbreak might begin. Some 1.6 million viruses are estimated to lurk in the world’s mammalian and avian wildlife, up to half of which could spill into humans; an untold number are attempting exactly that, at this very moment, bumping up against the people hunting, eating, and encroaching on those creatures. (And that’s just viruses: Parasites, fungi, and bacteria represent major infectious dangers too.) The only true certainty in the pandemic forecast is that the next threat will be here sooner than anyone would like.

    But scientists can at least make an educated guess about what might catalyze the next Big One. Three main families of viruses, more than most others, keep scientists up at night: flu viruses, coronaviruses, and paramyxoviruses, in descending order of threat. Together, those groups make up “the trifecta of respiratory death,” Sara Cherry, a virologist at the University of Pennsylvania, told me.

    Flu and coronavirus have a recent track record of trouble: Since 1918, flu viruses have sparked four pandemics, all the while continuing to pester us on a seasonal basis; some scientists worry that another major human outbreak may be brewing now, as multiple H5 flu viruses continue to spread from birds to mammals. The past two decades have also featured three major and deadly coronavirus outbreaks: the original SARS epidemic that began in late 2002; MERS, which spilled into humans—likely from camels—in 2012; and SARS-CoV-2, the pandemic pathogen that’s been plaguing us since the end of 2019. Common-cold-causing coronaviruses, too, remain a fixture of daily living—likely relics of ancient animal-to-human spillovers that we kept transmitting amongst ourselves.

    Read: Bird flu has never done this before

    Paramyxoviruses, meanwhile, have mostly been “simmering in the background,” says Raina Plowright, a disease ecologist at Cornell. Unlike flu viruses and coronaviruses, which have already clearly “proven themselves” as tier-one outbreak risks, paramyxoviruses haven’t yet been caught causing a bona fide pandemic. But they seem poised to do so, and they likely have managed the feat in the past. Like flu viruses and coronaviruses, paramyxoviruses can spread through the air, sometimes very rapidly. That’s certainly been the case with measles, a paramyxovirus that is “literally the most transmissible human virus on the planet,” says Paul Duprex, a virologist at the University of Pittsburgh. And, like flu viruses and coronaviruses, paramyxoviruses are found in a wide range of animals; more are being discovered wherever researchers look. Consider canine distemper virus, which has been found in, yes, canines, but also in raccoons, skunks, ferrets, otters, badgers, tigers, and seals. Paramyxoviruses, like flu viruses and coronaviruses, have also repeatedly shown their potential to hopscotch from those wild creatures into us. Since 1994, Hendra virus has caused multiple highly lethal outbreaks in horses, killing four humans along the way; the closely related Nipah virus has, since 1998, spread repeatedly among both pigs and people, carrying fatality rates that can soar upwards of 50 percent.

    The human versions of those past few outbreaks have petered out. But that may not always be the case—for Nipah, or for another paramyxovirus that’s yet to emerge. It’s entirely possible, Plowright told me, that the world may soon encounter a new paramyxovirus that’s both highly transmissible and ultra deadly—an “absolutely catastrophic” scenario, she said, that could dwarf the death toll of any epidemic in recent memory. (In the past four years, COVID-19, a disease with a fatality rate well below Nipah’s, has killed an estimated 7 million people.)

    All that said, though, paramyxoviruses are a third-place contender for several good reasons. Whereas flu viruses and coronaviruses are speedy shape-shifters—they frequently tweak their own genomes and exchange genetic material with others of their own kind—paramyxoviruses have historically been a bit more reluctant to change. “That takes them down a level,” says Danielle Anderson, a virologist at the Doherty Institute, in Melbourne. For one, these viruses’ sluggishness could make it much tougher for them to acquire transmission-boosting traits or adapt rapidly to spread among new hosts. Nipah virus, for instance, can spread among people via respiratory droplets at close contact. But even though it’s had many chances to do so, “it still hasn’t gotten very good at transmitting among humans,” Patricia Thibault, a biologist at the University of Saskatchewan who studied paramyxoviruses for years, told me.

    The genetic stability of paramyxoviruses can also make them straightforward to vaccinate against. Our flu and coronavirus shots need regular updates—as often as annually—to keep our immune system apace with viral evolution. But we’ve been using essentially the same measles vaccine for more than half a century, Duprex told me, and immunity to the virus seems to last for decades. Strong, durable vaccines are one of the main reasons that several countries have managed to eliminate measles—and why a paramyxovirus called rinderpest, once a major scourge of cattle, is one of the only infectious diseases we’ve ever managed to eradicate. In both cases, it helped that the paramyxovirus at play wasn’t great at infecting a ton of different animals: Measles is almost exclusive to us; rinderpest primarily troubled cows and their close kin. Most flu viruses and SARS-CoV-2, meanwhile, can spread widely across the tree of animal life; “I don’t know how you can eradicate that,” Anderson told me.

    The problem with all of these trends, though, is that they represent only what researchers know of the paramyxoviruses they’ve studied—which is, inevitably, a paltry subset of what exists, says Benhur Lee, a virologist at Mount Sinai’s Icahn School of Medicine. “The devil we don’t know can be just as frightening,” if not more, Lee told me. A pattern-defying paramyxovirus may already be readying itself to jump.

    Researchers are keyed into these looming threats. The World Health Organization highlights Nipah virus and its close cousins as some of its top-priority pathogens; in the U.S., paramyxoviruses recently made a National Institute of Allergy and Infectious Diseases list of pathogens essential to study for pandemic preparedness. Last year, the Bill & Melinda Gates Foundation announced a hefty initiative to fund paramyxovirus antiviral drugs. Several new paramyxovirus vaccines—many of them targeting Nipah viruses and their close relatives—may soon be ready to debut.

    Read: We have a mink problem

    At the same time, though, paramyxoviruses remain neglected—at least relative to the sheer perils they pose, experts told me. “Influenza has been sequenced to death,” Lee said. (That’s now pretty true for SARS-CoV-2 as well.) Paramyxoviruses, meanwhile, aren’t regularly surveilled for; development of their treatments and vaccines also commands less attention, especially outside of Nipah and its kin. And although the family has been plaguing us for countless generations, researchers still don’t know exactly how paramyxoviruses move into new species, or what mutations they would need to become more transmissible among us; they don’t know why some paramyxoviruses spark only minor respiratory infections, whereas others run amok through the body until the host is dead.

    Even the paramyxoviruses that feel somewhat familiar are still surprising us. In recent years, scientists have begun to realize that immunity to the paramyxovirus mumps, once thought to be pretty long-lasting and robust, wanes in the first few decades after vaccination; a version of the virus, once thought to be a problem only for humans and a few other primates, has also been detected in bats. For these and other reasons, rubulaviruses—the paramyxovirus subfamily that includes mumps—are among the potential pandemic agents that most concern Duprex. Emmie de Wit, the chief of the molecular-pathogenesis unit at Rocky Mountain Laboratories, told me that the world could also become more vulnerable to morbilliviruses, the subfamily that includes measles. If measles is ever eradicated, some regulators may push for an end to measles shots. But in the same way that the end of smallpox vaccination left the world vulnerable to mpox, the fall of measles immunity could leave an opening for a close cousin to rise.

    The next pandemic won’t necessarily be a paramyxovirus, or even a flu virus or a coronavirus. But it has an excellent chance of starting as so many other known pandemics have—with a spillover from animals, in parts of the world where we’ve invaded wild habitats. We may not be able to predict which pathogen or creature might be involved in our next big outbreak, but the common denominator will always be us.

    Katherine J. Wu

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