How Do Live Viral Vaccines Work?

Live viral vaccines are biological products that provide immunity against certain viral infections. Live viral vaccines stimulate the body’s immune system to produce antibodies against specific types of viruses and protect a person from diseases caused by these viruses.

Live viral vaccines are weakened (attenuated) forms of disease-causing viruses. Live viral vaccines produce a strong and often life-long immunity similar to that acquired from a natural infection, but without subjecting the person to the disease and its complications, because they only contain a small amount of the weakened viruses.

Live viral vaccines are derived by weakening the disease-causing viruses in laboratories, usually with repeated culturing. Live viral vaccines must be stored and handled with care because they are fragile and can be damaged by heat and light.

Live viral vaccines may not be safe for individuals with compromised immunity. People with weakened immune systems should consult with their health care providers before receiving live viral vaccines, because they may cause severe infections that their weakened immune systems may not be able to control.

Live viral vaccines approved by the FDA provide immunity against the following viral diseases:

• Febrile acute respiratory disease, caused by adenovirus type 4 and type 7
• Dengue disease, caused by dengue virus serotypes 1,2,3 and 4, spread by mosquitoes
• Zaire ebolavirus infection
• Influenza A and B infection
• Measles, mumps, rubella viral infections
• Chickenpox, caused by the varicella-zoster virus
• Gastroenteritis caused by several strains of rotavirus
• Smallpox, which has been eradicated worldwide
• Monkeypox, a disease caused by the monkeypox virus which is related to the smallpox virus
• Yellow fever, a disease spread by mosquitoes, affects the liver

Live viral vaccines are administered as single or a series of one-time doses, except in the case of the influenza virus vaccine which is administered annually before the flu season. Live viral vaccines may be administered through the following routes:

• Oral tablets, solutions, or suspensions
• Intranasal sprays
• Subcutaneous (SC) injections into the tissue under the skin
• Percutaneous administration into the skin
• Intramuscular (IM) injections into the muscle

Live viral vaccines approved by the FDA include:

• Adenovirus type 4 and type 7 vaccine for individuals of ages 17-50 years
• Dengue virus vaccine for children of ages 9-16 years with laboratory-confirmed previous dengue infection and living in endemic areas
• Ebola Zaire vaccine for adults
• Influenza intranasal vaccine for individuals of ages 2-49
• Measles, mumps, and rubella vaccine for routine immunization in children and adults, and immunization for pregnant women without evidence of immunity, after termination or completion of pregnancy
• Measles, mumps, rubella, and varicella vaccine for children of ages 12 months to 12 years
• Rotavirus oral vaccine for prophylaxis in infants of ages 6-32 weeks
• Smallpox vaccine, now no longer routinely administered since smallpox has been eradicated in the world
• Smallpox and monkeypox vaccine for adults who are at high risk for smallpox or monkeypox infection
• Varicella virus vaccine for individuals of age 12 months and older
• Yellow fever vaccine for individuals 9 months and older who live in or travel to yellow fever endemic areas, and laboratory personnel at risk for exposure

Side effects of live viral vaccines may include the following:

• Injection site reactions include:
  • Pain, burning, and stinging
  • Swelling
  • Rash
  • Vesicles (blisters)
  • Pruritus (itching)
  • Erythema (redness)
  • Induration (hardening of the tissue)
  • Hematoma
  • Discoloration
• Headache
• Pyrexia (fever)
• Runny nose
• Nasal congestion
• Myalgia (muscle pain)
• Arthralgia (joint pain)
• Fatigue
• Malaise
• Asthenia (weakness)
• Decreased exercise tolerance
• Chills
• Fussiness and irritability
• Nausea
• Vomiting
• Diarrhea
• Gastritis
• Gastroenteritis
• Abdominal pain
• Flatulence
• Constipation
• Hematochezia (blood in stool)
• Mouth ulcer
• Sore throat
• Cough
• Sneezing
• Sinusitis (inflammation of the sinuses)
• Rhinitis (inflammation of nasal passage)
• Nasopharyngitis (inflammation of nose and throat)
• Pharyngitis (throat inflammation)
• Epistaxis (nasal bleeding)
• Pneumonia
• Pulmonary congestion
• Wheezing
• Bronchospasm
• Dyspnea (shortness of breath)
• Bronchitis (inflammation of the bronchial passage)
• Pneumonitis (lung inflammation)
• Otitis media (middle ear infection/inflammation)
• Infections such as:
  • Atypical measles/measles
  • Candidiasis
  • Herpes zoster infection
  • Varicella infection
  • Influenza
  • Respiratory infection
  • Skin infections such as cellulitis and impetigo
• Parotitis (inflammation of the parotid glands)
• Orchitis (testicle inflammation)
• Epididymitis (inflammation of the coiled tube in the testicle that carries the sperm)
• Ataxia (impaired coordination, balance, and speech)
• Paresthesia (abnormal skin sensation)
• Bell’s palsy (facial muscle weakness or paralysis)
• Dizziness
• Cerebrovascular accident
• Guillain-Barre syndrome (neurological disorder)
• Syncope (fainting)
• Conjunctivitis (inflammation of the conjunctiva, the membrane over the whites of the eye and inner surface of eyelids)
• Eyelid edema
• Eye irritation
• Retinitis (inflammation of the retina)
• Necrotizing retinitis (retinitis with retinal tissue death), in immunocompromised individuals
• Optic neuritis (optic nerve inflammation)
• Retrobulbar neuritis (a form of optic neuritis)
• Ocular palsies (eye muscle weakness)
• Polyneuritis/polyneuropathy (simultaneous inflammation/damage to multiple nerves all over the body)
• Encephalitis (inflammation of the brain)
• Encephalopathy (damage to the brain)
• Acute disseminated encephalomyelitis (ADEM), inflammation of the brain and spinal cord
• Measles inclusion body encephalitis (MIBE), a condition that may occur in immunocompromised persons
• Subacute sclerosing panencephalitis (a progressive brain disorder related to measles), rare
• Aseptic meningitis (inflammation of the membranes around the brain and spinal cord)
• Meningoencephalitis
• Transverse myelitis (inflammation of spinal cord)
• Tremor
• Seizures
• Febrile seizures (convulsions caused by fever)
• Nerve deafness
• Ear pain
• Agitation
• Apathy
• Nervousness
• Dream abnormality
• Hypersomnia (excessive daytime sleepiness)
• Hypersensitive reactions such as:
  • Rash
  • Urticaria (hives)
  • Vesicular lesions (blisters)
  • Erythema multiforme (round red lesions like a bullseye)
  • Angioedema (swelling in the tissue under the skin or mucous membranes)
  • Facial edema
  • Peripheral edema
  • Anaphylaxis (severe allergic reaction)
  • Stevens-Johnson syndrome (a rare medical emergency with flu-like symptoms and a painful rash)
• Henoch-Schönlein purpura (a condition that causes generalized blood vessel inflammation)
• Lymphadenopathy (swelling of lymph nodes)
• Lymphadenitis (lymph node inflammation)
• Lymph node pain
• Feeling hot
• Abnormal sweating
• Arthritis (joint inflammation)
• Arthropathy (joint redness/tenderness/warmth/swelling/stiffness)
• Musculoskeletal pain
• Hip, neck, or leg pain
• Thrombocytopenia (low platelet count in the blood)
• Leukocytosis (increase in white blood cells, leukocytes)
• Aplastic anemia (anemia due to inadequate red blood cell production)
• Extravasation (leakage of fluid out of blood vessels)
• Hematuria (blood in urine)
• With rotavirus vaccination:
  • Gastroenteritis with vaccine viral shedding in infants with severe combined immunodeficiency disease (SCID)
  • Intussusception, a condition in which a part of the intestine slides into the adjacent part
  • Kawasaki disease, a condition that causes inflammation in the walls of blood vessels
• Severe dengue infection (with dengue vaccine)

Information contained herein is not intended to cover all possible side effects, precautions, warnings, drug interactions, allergic reactions, or adverse effects. Check with your doctor or pharmacist to make sure these drugs do not cause any harm when you take them along with other medicines. Never stop taking your medication and never change your dose or frequency without consulting your doctor.

Generic and brand names of live viral vaccines include:

• ACAM2000
• adenovirus types 4 and 7 live, oral
• dengue vaccine
• Dengvaxia
• Ebola Zaire vaccine
• Ervebo
• FluMist Quadrivalent
• influenza virus vaccine quadrivalent, intranasal
• Jynneos
• M-M-R-II
• measles mumps and rubella vaccine, live
• measles, mumps, rubella, and varicella vaccine, live
• MMRV
• ProQuad
• Rotarix
• RotaTeq
• rotavirus oral vaccine, live
• smallpox (vaccinia) and monkeypox vaccine, live, nonreplicating
• smallpox (vaccinia) vaccine, live
• varicella virus vaccine live
• Varivax
• yellow fever vaccine
• YF Vax
• Zostavax (DSC) - discontinued
• zoster vaccine live (discontinued)