The seven childhood diseases are measles, mumps, rubella, diphtheria, pertussis (whooping cough), tetanus, and polio. These are the illnesses that defined childhood health risks for generations and became the targets of the first routine vaccination programs. By the mid-1980s, vaccines existed for all seven, and mass immunization dramatically reduced their toll. Here’s what each disease actually does to the body and where things stand today.
Measles
Measles is one of the most contagious viruses known. Symptoms begin 7 to 14 days after exposure, starting with a high fever that can spike above 104°F, a cough, runny nose, and red, watery eyes. Two to three days later, tiny white spots called Koplik spots may appear inside the mouth. The telltale rash shows up 3 to 5 days after the first symptoms, beginning as flat red spots at the hairline and spreading downward across the body.
Before vaccination, measles infected nearly every child by adolescence. It remains dangerous today: the virus can cause pneumonia, brain swelling, and death, particularly in young children and those with weakened immune systems. In the United States, 2,288 confirmed measles cases were reported in 2025, with 48 separate outbreaks. As of late April 2026, another 1,792 cases had already been confirmed across 37 states, with 93% of those cases linked to outbreaks. These numbers reflect what happens when vaccination rates slip even modestly.
Mumps
Mumps is best known for causing painful swelling of the salivary glands along the jawline, giving children a distinctive “chipmunk cheek” appearance. It spreads through respiratory droplets and saliva, with symptoms appearing roughly two to three weeks after exposure. Most cases involve fever, headache, muscle aches, and fatigue along with the swelling.
The disease is usually mild in children, but complications become more serious with age. In adolescents and adults, mumps can cause inflammation of the testicles or ovaries, hearing loss, and, rarely, swelling of the brain or its surrounding membranes.
Rubella
Rubella, sometimes called German measles, is typically a mild illness in children. It produces a low-grade fever, swollen lymph nodes behind the ears, and a fine pink rash that starts on the face and spreads to the trunk and limbs. Many children barely feel sick.
The real danger is to pregnant women. If a woman contracts rubella during the first trimester, the virus can cause devastating birth defects, collectively known as congenital rubella syndrome. These include heart defects, deafness, intellectual disability, and liver or spleen damage. This risk to unborn children is the primary reason rubella vaccination became universal.
Diphtheria
Diphtheria is a bacterial infection that attacks the nose and throat. The bacteria produce a toxin that kills healthy tissue in the respiratory system, and the dead tissue builds up into a thick, gray coating called a pseudomembrane. This membrane can make it extremely difficult to breathe and swallow, and airway blockage is a potentially fatal complication.
If the toxin enters the bloodstream, it can damage organs far from the throat, causing kidney failure, heart muscle damage, and nerve problems. Before the vaccine became widely available in the 1920s and 1930s, diphtheria killed thousands of children each year in the United States. Today, cases in vaccinated populations are exceedingly rare.
Pertussis (Whooping Cough)
Pertussis starts out looking like a common cold: runny nose, mild cough, low fever. After a week or two, the cough intensifies into violent, uncontrollable fits that can last for minutes. The “whoop” comes from the sharp intake of breath after a coughing spell. Infants may not whoop at all but instead turn blue or stop breathing momentarily.
The coughing stage can last 6 to 10 weeks, earning pertussis the nickname “the 100-day cough.” It is most dangerous for babies under a year old, who face the highest risk of pneumonia, seizures, and brain damage from oxygen deprivation during coughing fits. Unlike some of the other seven diseases, pertussis has never been fully eliminated. Periodic outbreaks still occur because immunity from both vaccination and natural infection fades over time.
Tetanus
Tetanus is the odd one on this list because it isn’t contagious. The bacteria live in soil, dust, and animal waste, and enter the body through cuts, puncture wounds, or burns. Once inside, they produce a toxin that attacks the nervous system, causing muscles to lock up painfully. The jaw muscles are often affected first, which is why tetanus is commonly called lockjaw.
As the disease progresses, muscle spasms can spread to the neck, chest, abdomen, and limbs. Spasms can be severe enough to fracture bones. Without treatment, tetanus has a fatality rate of roughly 10 to 20 percent, and it is even higher in newborns. Because the bacteria are everywhere in the environment and cannot be eradicated, tetanus vaccination requires lifelong booster doses.
Polio
Poliomyelitis spreads through contaminated water and food, entering the body through the mouth and multiplying in the intestines. Most people infected with poliovirus, about 75%, have no visible symptoms at all. Roughly 1 in 4 develop flu-like symptoms that last 2 to 5 days and resolve on their own.
The feared outcome, paralysis, occurs in fewer than 1% of infections. But that small percentage translated into tens of thousands of paralyzed children each year during peak epidemics. Paralysis typically begins in one arm or leg and progresses outward, appearing 7 to 21 days after infection. When the muscles controlling breathing are affected, patients historically needed iron lung machines to survive. Global vaccination campaigns have reduced polio cases by over 99% since 1988, and the wild virus now circulates in only a handful of countries.
How Children Are Vaccinated Today
All seven diseases are covered by three vaccines on the current childhood immunization schedule. The DTaP vaccine protects against diphtheria, tetanus, and pertussis and is given in five doses: at 2 months, 4 months, 6 months, 15 to 18 months, and 4 to 6 years. The polio vaccine (IPV) follows a four-dose schedule starting at 2 months, with additional doses at 4 months, 6 to 18 months, and 4 to 6 years. The MMR vaccine covers measles, mumps, and rubella in two doses: the first at 12 to 15 months and the second at 4 to 6 years.
This schedule means that by the time a child enters kindergarten, they have full protection against all seven diseases. The spacing of doses isn’t arbitrary. Young immune systems need repeated exposures to build strong, lasting immunity, and the timing is designed to protect children as early as possible while their immune response is still maturing.
Why These Diseases Still Matter
It’s tempting to think of these seven illnesses as relics of the past, but the bacteria and viruses that cause them haven’t disappeared. They persist in the environment or circulate in under-vaccinated populations worldwide. When vaccination rates drop in a community, outbreaks follow quickly, as the recent measles surges in the U.S. have demonstrated.
Measles is particularly sensitive to gaps in immunity because it is so contagious. A single infected person in a room can transmit the virus to 90% of unvaccinated people nearby. Pertussis circulates more quietly, partly because immunity wanes and adults can carry and spread the bacteria with symptoms that look like a persistent cough. Tetanus will never go away because its source is the soil itself. These realities are why routine childhood vaccination remains one of the most consequential public health measures ever developed.