Approved for use in Canada on May 6, 2010, Priorix-Tetra™ contains live measles, mumps, rubella and varicella (chickenpox) viruses. It’s meant to replace 2-shot regimens using MMR and varicella vaccines. The Priorix-Tetra™ monograph published by GlaxoSmithKline (GSK) on the day of approval advises that it can be used for children 9 months to 6 yrs old but GSK also hopefully suggests it “may be used up to 12 yrs of age” based upon previous experience with their separate component vaccines.
Priorix-Tetra™ is supplied as sterile powder and separate diluting liquid. Before injection, it must be thoroughly mixed and administered shortly thereafter. Two of its viruses (measles and mumps) are cultured in chick embryo cells; the two others (rubella and varicella) are cultured on MRC-5 cells derived from lung tissue of an aborted human baby. Its other ingredients are amino acids, lactose, mannitol, neomycin sulphate and sorbitol.
The monograph warns that Priorix-Tetra™ is not to be injected into anyone who is hypersensitive to neomycin or any other of its ingredients. However, it denies concern about a history of contact dermatitis caused by neomycin. Unsurprisingly it also states that the vaccine should not be used on those who’ve previously shown signs of hypersensitivity when injected with measles, mumps, rubella and/or varicella vaccines. However, promoting their vaccine to the max, GSK allows, “Individuals who have experienced anaphylaxis after egg ingestion should be vaccinated with extreme caution, with adequate treatment for anaphylaxis on hand should such a reaction occur.” and, “A history of febrile convulsions or a family history of convulsions does not constitute a contraindication for the use of Priorix-Tetra™. Vaccinees with a history of febrile convulsions should be closely followed up as vaccine related fever may occur during the period ranging from 4 to 12 days after vaccination.” Concerning method of injection, they stipulate sub-cutaneous or intramuscular injection and stress that the vaccine “should under no circumstances be administered intravascularly or intradermally.”
One factor which makes Priorix-Tetra™ an even riskier choice than a first dose of concurrent MMR and varicella vaccines is that it’s been found about 1 ½ times more likely to increase the incidence of fever in children 9-27months old compared to the two shot regimen. Febrile seizures are said to be “rare”. Similarly, competitor Merck’s ProQuad® MMR-varicella vaccine has been found to increase the risk of fever and febrile seizures in children under 4 yrs.
Being a live virus vaccine, Priorix-Tetra™ is capable of causing infection. The monograph admits that, “rash, including measles-like, rubella-like and varicella-like rash” occur in 1-10% of 9-27 month old children after vaccination with Priorix-Tetra™. And it states, “Post-marketing experience suggests that transmission of varicella vaccine virus may occur very rarely between healthy vaccinees who develop a varicella-like rash and susceptible contacts.” It also admits, “Pharyngeal [throat] excretion of the rubella virus is known to occur about 7 to 28 days after vaccination with peak excretion around the 11th day.” But, “Transmission of measles, mumps and rubella viruses from vaccines to susceptible contacts has never been documented”. Of course no documentation doesn’t necessarily mean there’s never been transmission. Regarding mumps, “parotid swelling” is included in the list of “uncommon” clinical trial adverse reactions, the parotids being the salivary glands which commonly swell during mumps infection. And, “In rare cases a mumps-like condition with an abbreviated incubation period cannot be ruled out. In isolated cases transient, painful swelling of the testicles has been reported after combined mumps, measles, rubella vaccination.”
The vaccine is too new for its post-marketing adverse event data to be included in the monograph, so that for GSK’s MMR and varicella vaccines has been substituted. Disorders named are: thrombocytopenia and thrompocytopenia purpura (“bleeding or bruising more easily than normal due to a drop in blood platelets”); Kawasaki syndrome (“fever which lasts for more than five days, associated with a rash on the trunk sometimes followed by a peeling of the skin on the hands and fingers, swollen glands in the neck, red eyes, lips, throat and tongue”); meningitis; arthralgia and arthritis; encephalitis, Guillain Barré syndrome, peripheral neuritis and Transverse myelitis; anaphylaxis and erytheme multiforme (“severe condition of the skin that may affect the mouth and other parts of the body”).
Product Monograph: Priorix-Tetra™; GlaxoSmithKline Inc; Last revised April 3, 2013