A few months ago, I took care of Rosa, a 7-week-old chubby baby with peach-fuzz hair, in our emergency room at Harbor-UCLA Medical Center. I’m a pediatric resident at this safety-net hospital in southern Los Angeles County.

Her parents said she had had a runny nose and cough for about two weeks, and she was getting worse. Rosa, whose name has been changed to protect her identity,  was sleeping in her mother’s arms, when she stopped breathing — almost undetectable and so alarming. These episodes had been happening more frequently, so her parents brought her to the ER.

Fortunately, she spontaneously started to breathe again. 

A rapid nasal test confirmed my fears — she had pertussis, also called whooping cough. Because she was so young, I knew this infection could kill her. 

I wasn’t expecting to see pertussis, but vaccine-preventable diseases are on the rise, with lapses in immunizations during the pandemic and the increase in anti-vaccine sentiment in the U.S. This trend may get worse with the disruptions in federal health agencies under Robert F. Kennedy Jr. as the Secretary of U.S. Health and Human Services.

Kennedy has a long vaccine-hesitancy history, continues to push research that has been debunked and makes uncited claims, all of which further the public’s mistrust in our public health institutions. Last month, he disbanded the entire 17-member Centers for Diseases Control and Prevention Advisory Committee on Immunization Practices, a trusted, non-partisan panel of scientists and vaccine experts for over 60 years. He replaced the committee members with eight new panelists, some of whom are known vaccine critics. The American Medical Association has called for a Senate investigation of Kennedy’s actions. 

Rosa was not yet immunized, because she was too young. The diphtheria-tetanus-acellular pertussis (DTaP) vaccines are given when babies are 2, 4 and 6 months old, with a fourth dose for toddlers and a booster at 4 to 6 years. In addition, Tdap boosters containing lower doses of the vaccines are recommended during every pregnancy, at least every 10 years for others, and more often for people around infants. Young babies rely on those around them to have up-to-date vaccines to protect them. This is called herd or community immunity, meaning if enough people are vaccinated, it creates a defense shield that helps protect everyone.

But, community immunity is declining.

Before the pandemic in 2019-20, kindergartener vaccination rates for a few selected routine vaccines, including DTaP, polio and measles, were 95 percent, the minimum level needed for community immunity. During the 2023-24 school year rates fell to 93 percent and the CDC saw pertussis cases double. By June 2024, the annual reported cases returned to almost 10,000, the same number as before the pandemic. But during the first four months of 2025, nearly 8,500 cases were reported. If this rate continues, we could see 70,000 cases by the end of the year. This would be the highest number since 1948 when the first pertussis vaccines were introduced, risking more exposures for babies like Rosa who are too young to be immunized. 

Sadly, whooping cough isn’t the only vaccine-preventable disease coming back. Measles is surging with a vengeance, having caused outbreaks in 39 U.S. jurisdictions, including California, so far this year. The earliest and largest outbreak started in Texas in January, where two previously healthy, unimmunized children have died.

As of July 8, more than 1,280 cases of measles have been reported nationally. Nearly two-thirds of the cases occurred in children and teenagers, and 92 percent of them were unvaccinated or had an unknown vaccination status. If the outbreak continues, it will be considered an epidemic by January 2026.

Measles was declared eliminated in the U.S. in 2000, so I wasn’t expecting any chance of seeing cases. Now, when I see an ill child with rash, I have to consider this highly contagious infection. Measles is not a benign illness. About 30 percent of measles patients will have severe complications, such as pneumonia, ear infections and encephalitis (brain inflammation) or seizures, sometimes leading to death. Pregnant mothers with measles have an increased chance of stillbirths or infants born too early or too small. 

 Vaccine hesitancy, in the U.S. and globally, the loss of trust in public health and science and the threat to our health care infrastructure may allow once forgotten diseases to flourish, as well as make new vaccines more difficult to create. We may be more vulnerable during the next pandemic. 

So, what can we do? We can vaccinate routinely and consistently. And when using social media, we can think critically about the source of the information. Look to science and trained health care experts for reliable information. If you have questions, talk with your health care provider.

The American Academy of Pediatrics has recommendations for parents and guidance for health care providers on how to approach these conversations.

Thankfully, Rosa recovered. One thing that stuck with me was her parents’ feelings of guilt that they had caused her infection, though we never figured out how she contracted pertussis. I’ve learned that pointing fingers isn’t helpful — we are all connected. Our personal health care choices affect the health of our community. 

We each have a responsibility to our community and can help ensure that children aren’t the ones who suffer. 

Dr. Samantha Tope is in her senior year of pediatrics residency and chief residency at Harbor-UCLA Medical Center.