Infants May Not Be as Immune to Measles as Thought
“Measles is a serious disease, particularly among infants. Not only do they have a higher risk of infection, but also complications and hospitalizations. They’re also most vulnerable to death,” said senior study author Shelly Bolotin, a scientist at Public Health Ontario, in Toronto, Canada.
For the study, the researchers tested blood samples from 196 infants under 12 months of age to determine the presence of measles antibodies. The results were unexpected.
In their first month of life, 20% lacked sufficient antibodies to protect against the highly contagious virus, the study found. At 3 months, 92% had antibody levels below the protective threshold. By 6 months, none had antibodies at levels that could protect against measles.
Typically, babies have been presumed to be immune to measles for a year due to their mothers’ antibodies.
The authors attributed the quicker-than-expected loss of immunity to the type of protection received in the womb from their mothers.
Measles has been eliminated since 1998 in Canada, where the study took place. As such, mothers in the study probably got their protection from a shot and not through a previous infection, which may produce more antibodies. Nor would the mothers’ immunity have been boosted from measles circulating in the community.
“This study really underscores the need to protect infants in the first year of life,” Bolotin said.
Measles — a serious viral disease whose initial symptoms include a rash and fever — is highly contagious, especially among very young children. Though rare, complications — including pneumonia, hearing loss and death — are most common among vulnerable populations, such as infants, according to the U.S. Centers for Disease Control and Prevention (CDC).
In 2000, the CDC declared measles eradicated in the United States, thanks largely to a nationwide vaccination program. But the disease is present in other countries, and unvaccinated visitors sometimes bring the virus with them. That happened earlier this year, sparking repeated outbreaks that threatened the nation’s eradication status.