Do multiple childhood vaccines, such as Diphtheria, Tetanus, and Pertussis (DTaP), Measles, Mumps, and Rubella (MMR), and Varicella, cause harm?

Multiple Childhood Vaccines Do Not Cause Harm

Multiple childhood vaccines such as DTaP, MMR, and Varicella do not cause harm and are safe for simultaneous administration. 1 Extensive clinical experience and scientific evidence have consistently demonstrated that administering multiple vaccines during the same visit is both safe and effective, with no increase in adverse reactions compared to when vaccines are given separately.

Safety of Multiple Childhood Vaccines

Scientific Evidence Supporting Safety

• Simultaneous administration of the most widely used live and inactivated vaccines has not resulted in impaired antibody responses or increased rates of adverse reactions 1
• When administered at the same time and at separate sites, DTP (or DTaP), OPV (or IPV), and MMR have produced seroconversion rates and rates of side effects similar to those observed when the vaccines are administered separately 1
• The combined MMR vaccine yields results similar to administration of individual measles, mumps, and rubella vaccines at different sites, with no medical basis for administering these vaccines separately 1
• Response to MMR and varicella vaccines administered on the same day is identical to vaccines administered a month apart 1

Benefits of Simultaneous Administration

• Increases the probability that a child will be fully immunized at the appropriate age 1
• During a measles outbreak, one study indicated that about one-third of measles cases among unvaccinated preschool children could have been prevented if MMR had been administered at the same time as another vaccine 1
• Reduces the number of clinic visits required for immunization, increasing compliance
• Allows for timely protection against multiple diseases

Specific Safety Data for Common Childhood Vaccines

MMR Vaccine

• MMR vaccine has been extensively studied and found to be safe and effective 2, 3
• There is no evidence supporting an association between MMR immunization and:
  • Encephalitis or encephalopathy 3
  • Autism spectrum disorders 3
  • Cognitive delay, type 1 diabetes, asthma, dermatitis/eczema, hay fever, leukemia, multiple sclerosis, gait disturbance, and bacterial or viral infections 3

DTaP and Other Routine Vaccines

• Simultaneous vaccination of infants with DTaP, IPV, and either Hib vaccine or hepatitis B vaccine has resulted in acceptable response to all antigens 1
• The Advisory Committee on Immunization Practices (ACIP) encourages routine simultaneous administration of DTaP (or DTaP), IPV, Hib vaccine, MMR, and hepatitis B vaccine for children who are the recommended age 1

Potential Adverse Effects

While childhood vaccines are overwhelmingly safe, it's important to acknowledge the rare adverse effects that can occur:

• Febrile seizures: Can occur after MMR/MMRV vaccination at a rate of approximately 1 per 1150-1700 administered doses 3
• Idiopathic thrombocytopenic purpura (ITP): Estimated at about 1 case per 40,000 administered MMR doses, which is lower than the risk after natural infection with these viruses 3
• Local reactions: Pain at the injection site is the most common side effect 4
• Fever: A common side effect that is generally mild and transient 4

Best Practices for Vaccination

• Individual vaccines should not be mixed in the same syringe unless they are licensed for mixing by the FDA 1
• Simultaneous administration is particularly important if the child might not return for subsequent vaccinations 1
• For children with caregivers known to be compliant with healthcare recommendations, administering MMR and Hib vaccine at 12-15 months of age, followed by DTaP at age 18 months remains an acceptable alternative 1

Addressing Common Concerns

Despite the strong safety profile of childhood vaccines, parental concerns persist:

• More than half of parents express concerns regarding serious adverse effects, despite overwhelming evidence of vaccine safety 5
• Hispanic parents are more likely to follow their doctor's recommendations about vaccines for their children and less likely to have ever refused a vaccine, though they may still express concerns about adverse effects 5
• There is no medical basis for administering MMR components separately instead of the preferred combined vaccine 1

In conclusion, the scientific evidence strongly supports the safety and effectiveness of multiple childhood vaccines administered simultaneously. The benefits of protection against potentially serious diseases far outweigh the minimal risks of vaccination.