A quadrivalent measles, mumps, rubella, and varicella vaccine was well-tolerated and effective in children aged 12–23 months, according to data from a pair of studies conducted by Henry Shinefield, M.D., of the University of San Francisco, California, and his colleagues.
The studies, which were sponsored in part by Merck & Co., indicated that either a one- or two-dose vaccine containing antibodies to all four diseases was similar in safety and efficacy to a combination of the previous measles, mumps, and rubella vaccine (MMR II) and a separate dose of the varicella virus vaccine (Varivax).
In a randomized, multicenter study, 480 healthy children received either MMR II plus Varivax (VV) or the quadrivalent vaccine (MMRV) plus a placebo. Children in the MMRV group had significantly higher rates of elevated temperature from 5–12 days after vaccination, compared with the MMR-plus-VV group (28% vs. 19%), but the fevers were generally mild and averaged less than 2 days' duration. Adverse events were not significantly different between the two groups at 42 days after vaccination (Pediatr. Infect. Dis. J. 2005;24:665–9).
A measles-like rash was the most common adverse event in both groups; the rashes averaged 6 days' duration and were mild to moderate. The incidence of pain and redness at the injection sites and the proportion of children with at least one adverse event were similar between the groups.
In a separate study of 1,559 healthy children, antibody responses from the MMRV were equal to those from a combination of MMR plus VV (Pediatr. Infect. Dis. J. 2005;24:670–5).
The children were randomized to one of four treatment groups and received a quadrivalent vaccine with a low, middle, or high varicella-zoster virus (VZV) potency or a dose of MMR plus VV. Those in the quadrivalent groups received a second MMRV injection 90 days after the first injection.
The antibody rates in all three MMRV groups after the second injection were at least as high as the MMR-plus-VV group, and most of the children who had not responded to the VZV in the first injection did so after the second injection.
After the second injection, the observed response rates for measles in the low, middle, and high potency groups were 99.4%, 99.7%, and 100%, respectively, compared with 99.7%, in the MMR-plus-VV group. The observed response rates for varicella in the low, middle, and high potency groups were 99.7%, 100%, and 99%, respectively, compared with 93.1% in the MMR-plus-VV group. Similar response rates to those of measles and varicella were seen in the low, middle and high potency groups for mumps and rubella.
The incidence of measles-like rashes was similar in all groups, and the incidence of both varicella-like and measles-like rashes was lower in the MMRV group after the second MMRV injection, compared with the MMR-plus-VV group.
Approximately 70% of the children in any of the MMRV groups as well as the combination group reported at least one systemic adverse event, including fever, irritability, and upper respiratory tract infection. A febrile seizure suffered by a child in the middle potency group was the only severe adverse event thought to be vaccine related.
Febrile seizures might indeed be a cause for concern when using the quadrivalent vaccine, said Margaret Rennels, M.D., the American Academy of Pediatrics' coliaison to the Centers for Disease Control and Prevention's Advisory Committee on Immunization Practices.
But on the whole, the quadrivalent vaccine is a public health achievement, she said in an interview.
“Many of us believe that we should be giving a second dose of varicella and this [quadrivalent vaccine] would make that very easy,” said Dr. Rennels, clinical chief of infectious diseases at the University of Maryland, Baltimore.