What are live vaccines?

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Last updated: March 19, 2025View editorial policy

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From the Guidelines

Live vaccines contain weakened forms of living pathogens and include MMR (measles, mumps, rubella), varicella (chickenpox), rotavirus, yellow fever, oral polio (OPV), BCG (tuberculosis), smallpox, oral typhoid, and nasal flu (FluMist) vaccines, as stated in the most recent study 1.

Definition and Types of Live Vaccines

These vaccines work by causing a mild infection without serious symptoms, stimulating the immune system to develop protective antibodies and memory cells. The immune response to live vaccines is typically robust and long-lasting, often providing lifelong immunity with fewer doses than inactivated vaccines.

  • MMR (measles, mumps, rubella)
  • Varicella (chickenpox)
  • Rotavirus
  • Yellow fever
  • Oral polio (OPV)
  • BCG (tuberculosis)
  • Smallpox
  • Oral typhoid
  • Nasal flu (FluMist)

Administration and Contraindications

However, live vaccines are generally contraindicated for pregnant women and people with weakened immune systems because even the attenuated pathogens could potentially cause disease in these individuals, as noted in 1 and 1. Most live vaccines are administered by injection, though some (like rotavirus, oral polio, and nasal flu) are given orally or nasally, mimicking the natural route of infection and providing local immunity at entry sites.

  • Live vaccines should not be administered to patients with severely impaired specific immunity, as stated in 1.
  • Live-attenuated vaccines may be considered with caution in patients with autoimmune inflammatory rheumatic diseases, as discussed in 1.

Special Considerations

The evidence on MMR is mainly derived from the observational data in the pediatric population of patients with autoimmune inflammatory rheumatic diseases, and the use of glucocorticoids or methotrexate did not influence the antigen-specific antibody concentration or seroprotection rates, as reported in 1. Concerning vaccination against herpes zoster, two studies evaluated the safety of the live-attenuated zoster vaccine in patients with autoimmune inflammatory rheumatic diseases using immunosuppressive drugs, and the live-attenuated HZ vaccine may be considered in patients at risk, as stated in 1.

From the Research

Definition of Live Vaccines

  • Live vaccines are vaccines that contain a weakened or attenuated form of a virus or bacteria, which causes the body to produce an immune response without actually causing the disease 2, 3, 4, 5.
  • These vaccines are designed to mimic the natural infection, allowing the body to develop immunity against the disease-causing agent.

Examples of Live Vaccines

  • Measles, mumps, and rubella (MMR) vaccine is a live vaccine that contains weakened forms of the measles, mumps, and rubella viruses 2, 4, 5.
  • Varicella-zoster virus vaccine is a live vaccine that contains a weakened form of the varicella-zoster virus, which causes chickenpox 4, 5.
  • Rotavirus live vaccines are examples of live vaccines that contain weakened forms of the rotavirus, which causes severe diarrhea in children 3.

Characteristics of Live Vaccines

  • Live vaccines are typically administered in a single dose or a series of doses, depending on the specific vaccine and the age of the recipient 4, 5.
  • They can provide long-term immunity against the disease-causing agent, often lasting for many years or even a lifetime 2, 4, 5.
  • Live vaccines can also have non-specific effects, such as reducing the risk of other infections or diseases, as seen in the case of the MMR vaccine and its potential protective effect against childhood asthma 6.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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