Last November, the CDC shared that the U.S. had more than 23,500 cases of whooping cough, which is the highest number in 10 years. States like California and Minnesota saw big increases. In California alone, there were 2,000 cases from January to October last year.
Just last month, The New York Times reported that more than 60 babies under 4 months old were hospitalized in California because of whooping cough, and one of them died.
This report has found that worrying numbers show the dangers of falling vaccination rates.
But it’s not the only concern.
Research has also shown that the pandemic disrupted childhood vaccinations nationwide and rates have yet to recover. This leaves many children vulnerable to diseases like measles, mumps and rubella. They warn that if immunization rates continue to decline due to increasing distrust or stricter federal policies, then preventable diseases may reemerge across all age groups.
And it isn’t only the unvaccinated at risk; adults who were vaccinated years ago may also be susceptible to diseases now seen as childhood illnesses.
“It might take a year or two, but there’s no question,” Pejman Rohani, an infectious disease epidemiologist at the University of Georgia, recently told Apoorva Mandavilli, a global health reporter at The Times.
“We will have outbreaks,” he said.
Routine childhood immunization, introduced in the 20th century, is recognized as one of the most successful public health achievements of our time. It has effectively controlled diseases, enhanced health and quality of life, and increased lifespan. A 2024 study in The Lancet estimated that vaccines have saved 154 million lives globally since 1974, averaging 6 lives saved every minute, with 95% of those being children under five.
However, the Center for American Progress says that many people have forgotten how serious childhood diseases can be, partly because vaccines have greatly reduced illnesses. So as a result, many parents today may not think much about their importance.
The Lancet study also estimates that the number of parents who believe it’s “very” or “extremely important” for their kids to get vaccinated dropped from 94% in 2001 to 69% in 2024. They might not realize that the diseases vaccines protect against, which are now rare, used to cause the deaths of millions of children in the U.S. or leave them with lasting disabilities.
Still, “that could all change if we don’t continue with vaccine policies,” stated Dr. Alex Richter, a clinical immunologist at the University of Birmingham in Britain, where there are increasing cases of measles and mumps.
Richter explains that when many people in a community get vaccinated, it helps not only those who got the shots but also those who can’t get vaccinated, like some people with medical issues, the elderly, or those with weak immune systems. If fewer people get vaccinated, we are choosing to make the world a less safe place for a larger number of people.
For instance, Rubella, or German measles, poses significant risks to pregnant women and their babies. Vaccination is not an option for pregnant women due to the live virus in the vaccine, and right now, the risk is low in the U.S., with fewer than ten cases annually. However, this could increase if vaccination rates continue to decline, as rubella is a leading cause of preventable birth defects worldwide.
Mandavilli points out that anti-vaccine movements have targeted the M.M.R. vaccine, raising concerns about a potential rise in measles cases. Measles is highly contagious, remaining airborne for up to two hours, and one infected person can transmit it to up to 18 others. A similar issue arose in the late 1980s when budget cuts from the Reagan administration resulted in reduced vaccinations, particularly among low-income Black and Hispanic children.
The consequences were immediate. Between 1989 and 1991, measles infected over 55,000 Americans, resulting in 166 deaths.
What’s more, before the introduction of the measles vaccine in the 1960s, approximately 2.6 million people died from the disease annually worldwide. The virus compromises the immune system, which increases vulnerability to other infections. A 2015 study estimated that prior to widespread vaccination, measles caused nearly half of all infectious disease deaths in children. Today, the impact remains severe, with about 40 percent of those infected last year requiring hospitalization, according to the C.D.C.
Before the pandemic, M.M.R. and whooping cough vaccination rates were around 95% due to school entry requirements. While a drop was anticipated during the pandemic, rates fell below 93% for the 2023-24 school year. This put approximately 280,000 schoolchildren at risk for these diseases, heightening the potential for outbreaks in schools and public areas, as well as unvaccinated adults and those who poorly respond to vaccines or have received only one dose.
What’s more, fewer vaccinations have also led to a surprising outcome: vaccine protection can diminish over time, resulting in potential illness even among vaccinated adults during frequent outbreaks.
In particular, researchers in infectious disease modeling note that last year, 11% of the 284 measles cases in the U.S. occurred in individuals who had received one or two vaccine doses. This could account for the 27% of cases in adults over 20, an indication that measles no longer only affects children.
That said, it’s important to note that experts caution that whooping cough is a serious illness that vaccinated adults should still worry about. Initially, it can resemble a common cold but may progress into a severe, long-lasting cough known as the “100-day cough,” which ends with a whooping sound and can result in vomiting, broken ribs and breathing difficulties.
“There’s no way, I mean absolutely no way, that parents would tolerate that sort of reaction currently,” Dr. Kathryn Edwards, a vaccine expert who has studied whooping cough for 40 years, told The Times.
Previously, the whooping cough vaccine used whole bacteria cells, which were effective but often led to high fevers and seizures. A new version introduced in the 1990s is gentler on the body and offers long-term protection for most people, but it doesn’t fully prevent infections and immunity decreases over time. This may explain the rise in whooping cough cases among teenagers compared to younger children in recent outbreaks, which was actually, according to Edwards, was the first sign of declining vaccine immunity.
If vaccination rates fall to 75% in the coming years, older adults who received the original vaccine may remain safe, but unvaccinated individuals or those who got a newer vaccine as children could be at risk. Research indicates that the largest surge in cases would likely occur among infants too young to be fully vaccinated and children aged 5 to 15, who are the primary spreaders of the virus due to their high social contact at school.
With RFK Jr. likely to become the top health official in the U.S., and given his well-known opposition to vaccines and other controversial health ideas, experts are increasingly worried. They fear that vaccination rates could decrease and that this could have serious consequences for public health. They say that since vaccines are given to healthy people, they are often harder to promote than treatments. Plus, when it comes to side effects—which are rare—it may not bode well for public confidence, so the consequences can be severe.
“All you need is one or two of those stories to have a massive impact on vaccine takeup,” Dr. Richter said. “This is where you have a tension between community and individual.”
