The US has seen more measles cases in 2025 than in any year since 1992. | Jan Sonnenmair/Getty ImagesThe US has now recorded 1,277 measles cases this year, according to case data collected by Johns Hopkins University, making the current outbreak the most severe since 1992. The disease continues to spread, and by now most schools are out for the summer. July summer camps have opened and family vacations are picking up — all creating new opportunities for the virus to transmit.The next few months will be crucial for getting measles under control in the US.Three people have already died this year, the first measles deaths in the country in a decade. Most of the cases have been concentrated in a major outbreak in the Southwest — in New Mexico, Oklahoma, and Texas — but the virus is now also spreading in Arkansas, Illinois, Indiana, Kansas, Michigan, and Ohio. New outbreaks have recently sparked in Colorado, Montana and North Dakota. Though cases are still rising, they’re doing so more modestly than they were in March, when the country was seeing 100 or more new cases in a week. The measles outbreak does appear to be slowing down, experts say.But as cases continue to spread, the Centers for Disease Control and Prevention in mid-June urged kids’ summer camps to check their participants for measles immunity status. Measles is one of the world’s most contagious viruses and, with vaccination rates declining among children across the country, a lot of kids tightly cloistered for several days creates a prime environment for measles to spread quickly once introduced. The CDC’s new checklist for summer camps advises camp organizers to collect vaccine records from campers and keep the documentation on hand, to check campers and staff for any signs of fever or rash upon arrival, and to set up an isolation area if anyone begins to feel sick once camp has started.We are living in a new reality: Measles is spreading widely, vaccination rates are down, and the country’s top health official, Robert F. Kennedy Jr., has backed away from urging vaccination — even though they are 97 percent effective — as the best way to tamp down on measles’ spread. Kennedy has installed a new expert vaccine committee, opening up a review of the childhood vaccination schedule that includes the MMR shot. Given this more lax approach from the Trump administration, now is a good time to look out for ourselves and our loved ones. Here’s what you need to know about measles as the season with the biggest potential to spread heats up:Measles is an extremely contagious and dangerous virusThe US has been largely free of measles — a disease that still kills over 100,000 people worldwide every year, most of them young children — since the 1990s. Its risks have for most people become largely hypothetical.But for unvaccinated Americans, those risks remain very real. Measles is an extremely contagious virus that can lead to high fever and rash. Some patients develop pneumonia or encephalitis, a brain inflammation, both of which can be deadly.Measles has a fatality rate of 0.1 percent, but about 20 percent of cases can put patients in the hospital. The virus can be particularly dangerous for kids, especially young infants, as well as pregnant women and people who are immunocompromised.Some vaccine skeptics, including Kennedy, downplay the measles’ risk. “It used to be, when I was a kid, that everybody got measles. And the measles gave you lifetime protection against measles infection,” he said on Fox News in March.But measles has never been some harmless disease: In the decade before a vaccine was introduced in 1963, between 400 to 500 children died annually from measles in the US. From 1968 to 2016, there were about 550 measles deaths total in the US, according to the CDC. But before this year, it had been 10 years since any measles deaths had been recorded in the US.Even people who survive a measles infection can endure long-term health consequences, the risks of which are greater for vulnerable groups. Some of those infected in the current outbreak may have their health affected for years. Measles can cause what’s called immunity amnesia. The virus can wipe out more than half a person’s preexisting antibodies that provide protection against other pathogens. That can leave the patient at higher risk from other diseases for years after their measles infection.And in very rare cases, measles can lead to fatal brain swelling years after the initial infection. Patients can also experience hearing loss from ear infections that started their illness, while the people who develop acute encephalitis can suffer permanent neurological damage.You can protect your kids from measles. Here’s how.Vaccination is without a doubt the best defense against measles: two doses of the MMR vaccine — given to protect against measles, mumps, and rubella. It is one the most effective vaccines we have for any disease, and any risks from the vaccine are extremely low when compared to the dangers of measles itself.But in this new world, you’re more likely to see a measles outbreak in your community. People may want to be more proactive about protecting themselves and their loved ones. Here’s what you can do:Parents of young children — the group most at risk from measles — should talk to their pediatrician about measles vaccination. Children usually get their first shot around the time they turn 1 and receive another shot around age 5, but there is some flexibility. The CDC recommends that infants as young as 6 months receive one dose if they are traveling internationally, and the recommended age for the second dose ranges from 4 to 6 years old. Several leading public health experts, including former CDC director Rochelle Walensky, wrote in a JAMA op-ed over the spring that the recommendations should be updated to advise one shot for infants traveling in the US to areas with higher risk of exposure.There have been reports of vaccinated individuals getting infected during the current outbreaks, which has raised questions about how protected vaccinated people actually are. As good as it is, 97 percent effectiveness is not 100 percent, and it is possible to be vaccinated against measles and still get sick. For a very small percentage of people, the vaccine simply doesn’t produce immunity. It is also possible that immunity could wane over time, but that was previously not an issue because high vaccination rates had snuffed out the virus’s spread. Per the CDC’s estimates, about 3 percent of measles cases this year have been vaccinated people — consistent with the 97 percent efficacy rate.The priority should be vaccinating those people who do not have any protection at all: very young children and the people who weren’t vaccinated as kids. Pregnant women should not receive the vaccine, but women planning to become pregnant could consult with their doctor about a booster shot; likewise, people with immune conditions should talk to their doctor before getting any additional doses, because the vaccine’s live virus could present a risk depending on how compromised their immune system is.People who are at a higher risk may want to take extra precautions, such as wearing a face covering, if there are any reports of measles infections in their immediate area.For other people who have already been vaccinated but are still worried about transmission, it may be reasonable to consider a booster shot. But there are some important steps you should take first.First, check your vaccination records if you can find them. Anyone who received two doses as a child very likely had a successful immune response; only three in 100 people don’t. And if you received one dose — which was generally the norm before 1989 — you’re probably still protected, but it is slightly more likely that you never developed immunity, Aaron Milstone, an infectious disease pediatrician at the Johns Hopkins University School of Medicine, told me earlier this year.The next step would be to talk to your doctor, who can give you a “titer test” that measures the measles antibodies in your body. If they’re still present — then you should be good. But if they’re not, you may want to ask your doctor about getting an additional measles shot.The risks from measles should be kept in context: If you’re not near any confirmed measles cases, your personal risk probably remains low. If you’re vaccinated and have antibodies, you are very likely protected from the virus even if there is local transmission. But summer travel introduces some new risks: Several smaller outbreaks this year have been traced to infectious travelers passing through US airports.Measles can not be ignored. Milstone said he and his fellow infectious disease doctors could not believe it when they heard the news in February of a child’s death from measles in the United States of America.“You hope people don’t have to die for others to take this seriously,” Milstone said.