Diseases Vaccines Prevent
Childhood vaccines protect against 14 serious diseases. Many of these were once common killers of children. Here is what each disease does and why vaccination is so important.
Content reviewed against published CDC, WHO, AAP guidelines
Last reviewed: July 2026 · Editorial policy
Last reviewed:
Key takeaways
- Childhood vaccines protect against 14 diseases that can cause hospitalization, permanent disability, or death.
- Before vaccines, these diseases killed tens of thousands of US children every year.
- These diseases are rare today BECAUSE of vaccination — if rates drop, they return (as seen in recent measles and pertussis outbreaks).
- Infants are at the highest risk from many of these diseases because their immune systems are immature.
- Vaccination is the only reliable way to protect against most of these diseases.
The 14 Diseases
Measles(MMR)
Highly contagious viral disease causing high fever, rash, cough, and potentially pneumonia, brain inflammation (encephalitis), and death.
Severity
1 in 1,000 children develops brain inflammation. 1-3 in 1,000 die. Before the vaccine, 400-500 US deaths per year.
Current Status
Still circulates globally. US outbreaks occur in under-vaccinated communities (1,282 cases in 2019).
Whooping Cough (Pertussis)(DTaP)
Bacterial infection causing severe coughing fits that can last months. Infants may stop breathing. Can cause brain damage and death.
Severity
50% of infants under 1 year with pertussis require hospitalization. About 20 US infant deaths per year, mostly under 3 months.
Current Status
Never eliminated. 15,000-30,000 US cases reported yearly. Actual cases estimated 10x higher.
Polio(IPV)
Viral disease that can permanently paralyze muscles, including breathing muscles. No cure once paralysis occurs.
Severity
1 in 200 infections causes irreversible paralysis. 5-10% of paralyzed patients die when breathing muscles are affected.
Current Status
Near eradication globally but still endemic in some countries. Ongoing risk until fully eradicated worldwide.
Diphtheria(DTaP)
Bacterial infection creating a thick coating in the throat that can block the airway. Produces a toxin that damages the heart and nervous system.
Severity
Kills about 1 in 10 people who get it. Before vaccination, caused ~15,000 US deaths per year.
Current Status
Rare in the US due to vaccination. Still occurs in countries with low vaccine coverage.
Tetanus(DTaP)
Bacterial toxin causes severe muscle spasms and lockjaw. Bacteria enters through cuts or wounds. Not spread person-to-person.
Severity
Fatal in 10-20% of cases even with modern ICU care. Neonatal tetanus is nearly always fatal without treatment.
Current Status
Cannot be eliminated (bacteria lives in soil). Only vaccination provides protection.
Hib Disease (Meningitis & More)(Hib)
Haemophilus influenzae type b can cause meningitis, pneumonia, epiglottitis (airway swelling), and bloodstream infections. Most dangerous for children under 5.
Severity
Before the vaccine: ~20,000 severe cases/year in US children under 5. ~1,000 deaths. 15-30% of survivors have permanent brain damage.
Current Status
Reduced by >99% since vaccination began. Rare in vaccinated populations.
Pneumococcal Disease(PCV15/PCV20)
Streptococcus pneumoniae causes meningitis, blood infections (bacteremia), pneumonia, and ear infections. Leading cause of bacterial meningitis in young children.
Severity
Pneumococcal meningitis kills about 1 in 10 children and causes brain damage in many survivors.
Current Status
Dramatically reduced since PCV vaccine introduction. Still a significant cause of illness in under-vaccinated children.
Rotavirus(Rotavirus (RV))
Highly contagious virus causing severe vomiting and watery diarrhea. Leading cause of severe dehydration in infants and young children.
Severity
Before the vaccine: ~55,000-70,000 US hospitalizations and 20-60 deaths per year in children under 5.
Current Status
Dramatically reduced in vaccinated populations. Still common in unvaccinated children worldwide.
Hepatitis B(HepB)
Virus that attacks the liver. Can cause chronic infection, liver cirrhosis, and liver cancer. Infants are at highest risk of becoming chronic carriers.
Severity
90% of infected infants develop chronic hepatitis B (vs. 5% of infected adults). Chronic carriers have 25% lifetime risk of liver cancer or failure.
Current Status
Still infects ~1 million people worldwide annually. Vaccination has dramatically reduced childhood infection rates.
Hepatitis A(HepA)
Virus causing liver inflammation, fever, fatigue, nausea, and jaundice. Spread through contaminated food/water or close contact.
Severity
Usually milder in children than adults, but can cause weeks of illness. Rarely fatal but can cause liver failure in some cases.
Current Status
Outbreaks still occur in the US. Common in many developing countries.
Varicella (Chickenpox)(Varicella)
Highly contagious virus causing itchy blistering rash, fever, and fatigue. Can cause serious complications including skin infections, pneumonia, and brain inflammation.
Severity
Before the vaccine: ~100 US deaths per year, 10,000+ hospitalizations. Newborns and immunocompromised children at highest risk.
Current Status
Reduced by >90% since vaccination. Still occurs in unvaccinated individuals.
Mumps(MMR)
Viral infection causing painful swelling of salivary glands, fever, headache. Can cause meningitis, encephalitis, and deafness. In post-pubertal males, can cause orchitis (testicular inflammation).
Severity
1 in 10 get meningitis. Permanent deafness in 1 in 20,000. Was a leading cause of childhood deafness before vaccine.
Current Status
Outbreaks still occur in close-contact settings (colleges, camps) even with vaccination.
Rubella (German Measles)(MMR)
Usually mild in children, but devastating if a pregnant woman is infected — causes Congenital Rubella Syndrome (deafness, blindness, heart defects, intellectual disability).
Severity
CRS causes severe birth defects in up to 85% of babies whose mothers are infected in the first trimester.
Current Status
Eliminated in the US since 2004 due to vaccination. Still occurs in countries with low vaccine coverage.
Influenza (Flu)(Annual Flu Shot)
Respiratory viral infection causing fever, cough, body aches. More severe in young children. Can cause pneumonia, dehydration, and worsen chronic conditions.
Severity
Average 100-200 US pediatric deaths per year. More than half of children who die from flu were previously healthy.
Current Status
Circulates annually. Vaccination recommended yearly for everyone 6 months and older.
The Impact of Vaccines: Before and After
| Disease | Before Vaccine (US/yr) | After Vaccine (US/yr) |
|---|---|---|
| Measles | ~530,000 cases, 400-500 deaths | <200 cases (non-outbreak years) |
| Pertussis | ~200,000 cases, 8,000+ deaths | ~15,000-30,000 cases, ~20 deaths |
| Polio | ~21,000 paralytic cases/year | 0 (eliminated in US since 1979) |
| Hib Disease | ~20,000 cases, ~1,000 deaths | <30 cases/year |
| Diphtheria | ~175,000 cases, ~15,000 deaths | 0-5 cases/year |
| Rubella (CRS) | ~20,000 CRS cases (1964-65 epidemic) | 0 (eliminated in US since 2004) |
Source: CDC MMWR, Historical Vaccine-Preventable Disease Data
Related Vaccine Topics
Frequently asked questions
Are these diseases really still a threat?
Why vaccinate against diseases that are rare in the US?
Which of these diseases is most dangerous for babies?
Can my baby die from vaccine-preventable diseases?
Bottom line
Childhood vaccines protect against 14 diseases that once killed or permanently disabled tens of thousands of children every year in the US alone. These diseases are not gone — they are held in check by vaccination. Every dose your baby receives is a shield against a specific, real threat.
It can be hard to feel urgency about diseases you have never seen. That is actually a testament to how well vaccines work. You are part of the generation keeping these diseases at bay.
Our commitment to accuracy
Every page is reviewed against published guidelines from authoritative medical organizations including the CDC, WHO, AAP, ACOG, ASHA, and NIH.
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