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CDC urges vaccination amid rise in measles cases in the US and globally

Johannes Eisele/AFP/Getty Images

US health officials are warning doctors about the dramatic rise in measles cases around the world, and advising families traveling to a measles-affected country to get babies as young as 6 months vaccinated before they go.

The US Centers for Disease Control and Prevention issued a health alert to doctors on Monday to increase awareness of the international spread of measles, and urged them to vaccinate infants a few months ahead of the typical schedule if families are planning to go abroad.

The warning comes ahead of the busy spring and summer travel season. Many countries, including Austria, Philippines, Romania and the United Kingdom–destinations frequented by American tourists–are experiencing measles outbreaks, the CDC noted.

The CDC also warned about lagging vaccination rates in 36 US states where fewer than 95% of kindergarteners have been vaccinated against measles, putting them below the herd immunity threshold. Herd immunity is the portion of the population that must be immunized against an infection to prevent its spread through the community.

Even so, vaccination rates against measles in the U.S. are “pretty strong,” said Dr. Nirav Shah, CDC’s principal deputy director, so this isn’t a situation like Covid, where everyone is susceptible.

“For vaccinated individuals … the likelihood of contracting measles is thankfully not what it was in days gone by because the vaccination rates are high,” Shah said. “That said, we are concerned that vaccination rates have fallen just a little bit from 95% to 93%.”

Shah says two percentage points may not seem like a lot, but across the population, it represents about 250,000 kindergarteners who are unprotected.

The measles vaccines is considered one of the most protective. Two doses are about 97% effective at preventing infection, while a single dose is about 93% effective against infection.

“The overwhelming scientific evidence shows that vaccines remain among the most effective and safest intervention to both prevent individual illness and protect the health of the public,” said Dr. Jesse Ehrenfeld, president of the American Medical Association, said in an emailed statement.

In updated travel guidelines, the CDC is advising international travelers who are unsure about their vaccination status to see a doctor at least six weeks before their trip to make sure they have time to be fully immunized. Previous guidelines recommended seeing a doctor at least a month before the planned trip abroad.

Normally, infants get their first measles, mumps and rubella shot at a year of age. The CDC says it is recommending the vaccination timeline be pushed up a few months to protect babies who have no immunity against the highly contagious infection.

The CDC also recommends that unvaccinated children who are at least a year old get two doses of that measles containing vaccine at least 28 days apart before they travel.

Measles virus can linger in the air for two hours after an infected person has passed through a room. People can also become infected if they touch a surface with virus particles, then touch their eyes, nose, or mouth. People can spread measles up to four days before and four days after they develop the characteristic rash.

Approximately 9 out of 10 exposed individuals who don’t have immunity against the virus from previous infection or vaccination will catch it themselves.

Travelers who get sick with a rash, high fever, cough, runny nose, and red, watery eyes should seek medical attention, but the CDC advises giving the clinic some advance notice before you go, so they can take precautions to prevent potential measles spread.

The CDC says that 46 countries currently have high numbers of measles cases, including 26 in Africa, four in Europe, eight in the Middle East, seven in Asia, and two in Southeast Asia

The US has officially eliminated measles as an endemic infection, but the nation still sees imported cases every year. These cases are usually unvaccinated US residents who become infected during international travel.

The US is on pace for a busy year. So far in 2024, the US has seen 58 measles cases in 17 jurisdictions, according to the CDC — the same number of cases seen in all of 2023 — and some were spread locally.

Recent cases in the US have been reported in Chicago, California, Arizona, Florida and Pennsylvania.

The CDC is warning all international travelers that they may be susceptible to measles if they have not been fully vaccinated at least two weeks prior to departure or have not had measles in the past.

Measles can be severe in all age groups and can lead to serious complications, such as pneumonia and death.

Groups who are more likely to face severe complications include children younger than age 5, adults older than 20 years of age, pregnant women, and people with compromised immune function.

Many countries have seen declines in childhood vaccinations. Over 61 million doses of vaccines that protect against measles were missed during the Covid-19 pandemic, increasing the risk of measles outbreaks, according to the CDC.

That led to a steep rise in measles cases around the globe. For example, the WHO’s European region, which includes parts of Asia, had less than 1,000 measles cases in 2022 and more than 30,000 last year.

WHO’s most recent data shows that measles cases jumped 18% around the globe last year to around 9 million. Measles deaths increased 43% to about 136,000.

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