Four-in-one childhood vaccine gets FDA go-ahead

The US Food and Drug Administration (FDA) this month approved Merck's ProQuad, the first vaccine approved in the United States that protect against measles, mumps, rubella, and varicella in children 12 months to 12 years old in a single dose. The formulation was also approved for use in children 12 months to 12 years old if a second dose is to be administered. ProQuad combines two Merck vaccines: MMR II and Varivax.

"Until now, a young child had to undergo two separate vaccinations against these diseases" said Henry Shinefield, MD, clinical professor of pediatrics and dermatology, University of California School of Medicine, San Francisco. "The approval of ProQuad makes it more likely that children can gain protection against these four diseases because fewer shots can potentially mean better compliance,"

"By allowing vaccination against chickenpox to occur simultaneously with vaccination against measles, mumps, and rubella," Dr.Shinefield noted, "ProQuad can help increase the number of children vaccinated against chickenpox at the earliest recommended time-upon a baby's first birthday."

According to the report, "Combination Vaccines for Childhood Immunization," issued by the Advisory Committee on Immunization Practices in 1999, potential advantages of a combination vaccine include a reduction in multiple injections, more timely vaccination coverage, a reduction in the cost of stocking and administering separate vaccines, and a reduction in the cost of care for parents because fewer office visits are needed.

The persistence of antibody at one year after vaccination was evaluated in 2,107 children enrolled in clinical trials. The antibody persistence rate one year after a single dose of ProQuad was 98.9% against measles; 96.7% against mumps; 99.6% against rubella, and 97.5% against chickenpox. Duration of protection from these four diseases after vaccination with ProQuad is unknown.