- A measles outbreak in American Samoa has led to 49 cases.
- Measles can be contained in areas with high vaccination rates, however, declining vaccination rates across the globe have allowed measles to spread in areas where it was previously eliminated.
- According to estimates, in 2021, over 1.7 million children across 28 countries and territories of the Americas hadn’t received the initial dose of the measles, mumps, and rubella (MMR) vaccine.
American Samoa is currently experiencing a measles outbreak that’s led to two laboratory-confirmed cases and 49 suspected cases.
The governor of American Samoa declared a public health emergency on April 24, announcing that all schools and childcare facilities will shut down in-person classes and utilize online or distance learning for three weeks.
The U.S. territory is hosting mass vaccination events for babies and children six months and older to boost vaccination rates in the region and requiring anyone who tests positive or has been exposed measles to isolate for up to 21 days.
Measles can be contained in areas with high vaccination rates, however, declining vaccination rates across the globe have allowed measles to spread in areas where it was previously eliminated.
As long as there are areas where the vaccination rate falls below about 90%, opportunity exists for measles to infect susceptible people and spread.
“Childhood vaccination rates fell precipitously in some communities during the pandemic so low coverage in areas where direct travel from American Samoa is possible could easily spread the outbreak further,” Jennifer Horney, PhD, MPH, a disaster epidemiologist and founding director of the University of Delaware’s epidemiology program, told Healthline.
According to Horney, this was a huge victory — by 2008, cases in the U.S. had declined from three to four million a year before the vaccine was introduced to less than 100.
But in recent years declining vaccination rates have allowed measles to spread, causing outbreaks in many parts of the world, says Horney.
According to estimates, in 2021, over 1.7 million children across 28 countries and territories of the Americas hadn’t received the initial dose of the measles, mumps, and rubella (MMR) vaccine.
The recommended vaccination rate is 95%, however, in 2021 regional coverage in the Americas was 85%.
The
“With fewer people immune, the virus can be introduced and propagate throughout a population,” says Erica Susky, a certified infection control practitioner based in Toronto, Canada.
Adding fuel to fire, measles is also incredibly contagious.
“Each case typically leads to another 12-18 cases among a susceptible population, and those who are infected can spread the disease for four to five days prior to having any symptoms,” says Horney.
Due to declining vaccination rates, millions of children around the world are susceptible to the infection, allowing measles to make a bit of a comeback.
“The American Samoa experience is due to less people being vaccinated combined with someone who may have introduced the virus to the island, perhaps by travel,” says Susky.
There is always the chance that the measles outbreak could spread beyond American Samoa.
If the territory can get vaccine coverage to 90%, it would be difficult for the outbreak to spread more widely, says Horney.
American Samoa’s public health department is heavily invested in containing the outbreak as quickly as possible.
“Containment requires rapid vaccination of any close contacts including siblings, school contacts, and those that could have been exposed while seeking health care at the same location as the case,” says Horney.
That said, if an infected person travels to a region with low vaccine coverage, there’s a high risk the outbreak could spread.
Measles has a
As a result, people can spread it easily without knowing it, Susky says, which is what is playing out in many parts of the world.
“Outbreaks of measles are occurring in more and more places where it was mostly eradicated, such as in the USA and Canada,” Susky says.
“If the new areas where measles is introduced via travel have declining vaccine rates where herd immunity is not achieved, there will be a risk of measles propagating here,” she said.
American Samoa is currently experiencing a measles outbreak that’s led to two laboratory-confirmed cases and 49 suspected cases. Measles can be contained in areas with high vaccination rates, however, declining vaccination rates across the globe have allowed measles to spread in areas where it was previously eliminated. If an infected person travels to a region with low vaccine coverage, there’s a high risk the outbreak could spread.