A projected shortage of the quadrivalent measles-mumps-rubella-varicella vaccine means that children who require immunization for these diseases will need to get two shots instead of the single combination vaccine until supplies of the latter are replenished, according to the Centers for Disease Control and Prevention.
The quadrivalent vaccine (ProQuad) shortage is expected to begin in July, although actual timing will depend on market demand, and last at least through the end of 2007 (MMWR 2007 May 11;56:453).
ProQuad's manufacturer, Merck & Co., is attributing the shortfall to lower-than-expected amounts of varicella zoster virus (VZV) in its recent batch of bulk vaccine.
Merck notified the CDC earlier this year of its intent to use its available supply of VZV in the production of its varicella-only vaccine (Varivax) and its zoster vaccine (Zostavax) and to temporarily halt the production of ProQuad.
In anticipation of the shortage, Merck is requesting that physicians begin transitioning from the quadrivalent vaccine to the measles-mumps-rubella vaccine (MMR-II) and the varicella vaccine.
The company expects to have adequate supplies of both of the latter vaccines to fully implement the recommended immunization schedules, according to the notice.
“This will allow for continued use of varicella vaccine for all age groups, including the routine two-dose schedule for children aged 12–15 months and 4–6 years, catch-up vaccination with the second dose for children or adolescents who received only one dose, and vaccination with two doses for other children, adolescents, and adults without evidence of immunity,” the notice said.
Additionally, the company expects to have an adequate supply of zoster vaccine for routine vaccination of adults who are aged 60 years and over.