Wisconsin health officials want some babies vaccinated against measles months earlier than usual as the state battles its worst outbreak in more than 35 years.
The Wisconsin Department of Health Services (DHS) issued Health Alert #73 on Nov. 3 recommending the measles, mumps and rubella (MMR) vaccine for infants aged 6 to 11 months "if they are members of a family or community that is likely to be exposed to measles." Children normally receive their first MMR dose between 12 and 15 months.
The alert, signed by Dr. Ryan Westergaard, DHS chief medical officer and state epidemiologist, stressed that early vaccination is not recommended for every infant in Wisconsin or for every child in any one county. Parents should talk to their child's pediatrician about whether it makes sense for their family.
Kenosha County was not listed among the counties reporting measles cases on the DHS page as of Nov. 10. But the statewide guidance applies to any Wisconsin family that meets the exposure criteria, and state officials say the outbreak is still expanding.
How big is the outbreak?
As of Nov. 3, DHS had confirmed 429 measles cases and eight hospitalizations across 11 counties, according to the health alert. The DHS outbreaks page, updated Nov. 10, listed 551 confirmed cases across 17 counties, with nine hospitalizations and one death.
Most cases are clustered in Grant, Lafayette and Iowa counties in southwestern Wisconsin. Nearly all cases have occurred in unvaccinated people, the DHS alert stated. Transmission has been concentrated in close-knit communities and social networks where vaccination coverage is low, primarily within some Amish and Mennonite communities, according to the alert.
An infant in Grant County died of measles, the state's first measles-related death since 1990, as first reported by the Milwaukee Journal Sentinel.
Why vaccinate early?
The DHS alert explained that infants are especially vulnerable to measles. In U.S. surveillance from 2001 to 2022, infants younger than 12 months had significantly higher odds of complications, hospitalization and severe disease than children aged 5 to 19.
Most infants lose protective maternal antibodies by about 3 months of age, the alert stated. Without an early dose, most stay unprotected until the routine MMR dose at 12 to 15 months.
The early dose is safe, according to the alert. Side effects are no more frequent than after doses given at older ages. But it is less effective. The estimated effectiveness of a dose given before 9 months is about 58%, compared with about 83% for doses given at 9 months or older, the alert stated. Two full doses of MMR are about 97% effective at preventing measles.
An infant who receives the early dose still needs two more doses to complete the routine series, according to the DHS guidance.
Who qualifies for early vaccination?
The DHS alert laid out specific criteria. An early dose is recommended when an infant lives with someone who has confirmed or probable measles, or when a household member has regular contact with a family or community affected by the outbreak.
It also applies when an infant's family belongs to a close-knit community where measles is spreading, as identified by the local health department. Local health departments identify qualifying families through case investigations and contact tracing.
Families outside those criteria who want the early dose should discuss it with their doctor, the alert stated. Clinicians can contact their local health department for help assessing exposure risk.
What Kenosha families should know
The outbreak is spreading because of low vaccination rates, Westergaard told WPR. Wisconsin has the second-lowest measles vaccination rate among kindergartners, WPR reported.
DHS urges all Wisconsin residents to check their vaccination status. The MMR vaccine is available through health care providers, local health departments and pharmacies. The Wisconsin Vaccines for Children program covers vaccine costs for eligible children, and the Vaccines for Adults program can help uninsured adults.
Kenosha County Public Health can be reached at 262-605-6700.
Anyone who suspects measles exposure should call their health care provider before visiting a clinic or emergency room. Westergaard told WPR: "This is a unique case where we don't want to just show up at the clinic or show up at the emergency department, but call first."
