News Scan for Nov 21, 2019

Waning measles antibodies in infants
;
Eastern equine encephalitis and preparedness

Study: Maternal measles antibodies fade quickly in infants

According to a small study today in Pediatrics, maternal antibodies to measles passed to infants in pregnancy dropped quickly after birth, with 92% of infants showing antibodies below the protective threshold by 3 months. By 6 months of age, all the infants were unprotected against measles, based on their antibody levels.

The study included 196 sera samples from infants under 12 months of age seen at a tertiary pediatric hospital in Ontario. The infants' sera was tested for measles antibodies and stratified by age. In the first month, 20% of infants (5 of 25) had antibodies below the protective threshold, which increased to 92% (22 of 24) by 3 months, the authors said.

The authors said the study results challenge the presumption that infants are protected against measles via maternal antibodies until 6 months of age, and would suggest the usefulness of earlier vaccination in a post-exposure scenario. Unless international travel is planned, most countries in which measles is eliminated recommend an initial dose of measles, mumps, and rubella (MMR) vaccine at 12 to 15 months of age.

In an accompanying commentary, two US experts write that vaccine hesitancy and failure to vaccinate are behind the recent resurgence of measles, and warn that altering the timing of routine MMR vaccination would do little to stop transmission among unvaccinated children. They add that earlier vaccination could be useful, however, during outbreaks.

"Health care providers must work to maintain high levels of coverage with 2 doses of MMR among vaccine-eligible populations and minimize pockets of susceptibility to prevent transmission to infants and prevent reestablishment of endemic transmission," the authors write. "During outbreaks, an early vaccination schedule is warranted and recommended because of the increased risk of infection."
Nov 21 Pediatrics study
Nov 21 Pediatrics commentary

 

Federal officials say EEE spike exposes preparedness gaps

Experts from the National Institute of Allergy and Infectious Diseases (NIAID) yesterday weighed in on the recent spike in Eastern equine encephalitis (EEE) cases, noting that although the event doesn't signify a major threat, it does expose a lack of preparedness for emerging diseases. NIAID Director Tony Fauci, MD, and his colleagues David Morens, MD, and Gregory Folkers, MPH, covered the topic in a commentary in the New England Journal of Medicine.

The United States typically averages about 7 EEE cases each year, but so far this year, the Centers for Disease Control and Prevention has received reports of 36 cases from 8 states, 14 of them fatal.

The NIAID scientists described the history of EEE in the United States, which experienced 12 epidemics or epizootics from 1839 to 1959. Though the virus typically circulates in Culiseta melanura mosquito reservoirs and various birds and other small animals found in forested wetlands, spillovers sometimes occur involving other animals such as horses, game birds, or poultry, or humans.

The experts write that spillovers typically include unpredictable and involved complex interactions in human behaviors, weather, environmental factors, bird movements, and other variables. They note that EEE virus is considered a possible bioweapon, because it can spread through the aerosol route.

In covering the clinical signs and diagnosis of EEE, they note that no antiviral drugs have been shown to be effective. And though several vaccines are in development, there aren't strong financial incentives to advance them. Health officials depend on surveillance as a prevention tool, and the authors write that the nation's ability to control mosquito-borne viruses isn't much better than it was a century ago.
Nov 20 N Engl J Med commentary
Nov 20 NIAID press release

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