Focusing on healthy aging might encourage older adults to get vaccinated
In some cases, vaccinated people can transmit measles, finds a review and meta-analysis of 33 reports published late last week in Expert Review of Vaccines.
“Measles transmissions from vaccinated cases, although relatively uncommon, must be considered in public health investigations, as such transmissions can contribute to outbreaks,” wrote the authors, led by researchers at Public Health Ontario.
A third of disease spreaders had received 2 doses
It’s estimated that measles vaccines have prevented about 94 million deaths from 1974 to 2024. Prior to the vaccine’s introduction, measles caused 2.6 million deaths every year worldwide.
The two-dose measles shot helped many countries eliminate the fast-spreading respiratory illness. But that trend has been shifting as vaccine hesitancy increases. This year, the United States has seen its most measles cases since 1991.
For the review, the scientists examined peer-reviewed studies, as well as reports published outside of traditional publishing to understand if those vaccinated against measles might spread the illness to others. Some people can experience secondary vaccine failure, in which a natural, gradual loss of vaccine-created immunity is amplified because there’s little circulating virus to boost the immune response.
Across all included reports, 70 out of 890 vaccinated people (7.9%) passed measles to others, which caused 237 secondary cases of the illness. Thirty-one percent of the transmitters, 22 people, had received two doses of the measles vaccine.
Measles transmissions from vaccinated cases, although relatively uncommon, must be considered in public health investigations, as such transmissions can contribute to outbreaks.
The most common symptoms among the 19 transmitters with symptom information were rash (16 people), fever (11) and cough (11). Most vaccinated people who spread measles experienced milder symptoms and a shorter illness than those who weren’t vaccinated. Most often, cough, breathing, or talking likely caused measles to spread.
