Sunday September 22, 2019

U.S. Measles Outbreak Raises Concerns About Immunity in Adults

This has occurred even in adults with two documented doses of the vaccine, said Dr. Michael Phillips, chief epidemiologist at NYU Langone Health, which serves parts of New York City, a hot spot in the U.S. outbreak.

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People vaccinated in the United States since 1989 would most likely have received two doses of the combined measles, mumps and rubella (MMR) shot under federal guidelines, and that is still considered the standard for protection. Pixabay

Adults in the United States who were vaccinated against measles decades ago may need a new dose depending on when they received the shot and their exposure risk, according to public health experts battling the nation’s largest outbreak since the virus was deemed eliminated in 2000.

Up to 10 percent of the 695 confirmed measles cases in the current outbreak occurred in people who received one or two doses of the vaccine, according to the U.S. Centers for Disease Control and Prevention.

The figure illustrates what can happen when a large number of individuals, even those who have been vaccinated, are exposed to the measles. CDC recommends that people who are living in or traveling to outbreak areas should check their vaccination status and consider getting a new dose.

Dr. Allison Bartlett, an infectious disease expert at the University of Chicago Medicine, said the “continued vulnerability to infection” is why high-risk adults such as healthcare workers are routinely advised to get a second dose of the measles vaccine if they have not had one.

But knowing your vaccination status can be tricky, experts said.

“It’s complicated and often futile because it’s very difficult to resurrect those old records,” said Dr. William Schaffner, an infectious disease expert at Vanderbilt University Medical Center.

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Los Angeles County Department of Public Health experts, Muntu Davis, Health Officer, left, and Director Dr. Barbara Ferrer answer questions regarding the measles response and the quarantine orders during a news conference in Los Angeles Friday, April 26, 2019. VOA

People vaccinated in the United States since 1989 would most likely have received two doses of the combined measles, mumps and rubella (MMR) shot under federal guidelines, and that is still considered the standard for protection.

Anyone vaccinated between 1963 and 1989 would likely have received only one dose, with many people immunized in the earlier years receiving an inactivated version of the virus. Americans born before 1957 are considered immune as they would have been exposed to the virus directly in an outbreak.

Merck & Co Inc is the sole U.S. provider of the MMR vaccine. The company said in a statement that it has “taken steps to increase U.S. supply” of the vaccine due to the current outbreak.

HIGHLY CONTAGIOUS

The measles virus is highly contagious and can cause blindness, deafness, brain damage or death. It is currently spreading in outbreaks in many parts of the world.

According to the World Health Organization, 95 percent of a population needs to be vaccinated to provide “herd immunity,” a form of indirect protection that prevents infection in people too young or sick to be vaccinated. U.S. public health officials have blamed the current outbreak in part on rising rates of vaccine skepticism that have reduced measles immunity in certain communities.

For travelers to outbreak areas abroad, the CDC recommends adults consider getting another dose of MMR unless they have proof of receiving two prior doses, take a blood test showing immunity, or were born before 1957.

In general, the CDC says two doses of the measles vaccine should provide 97 percent protection; one dose should offer 93 percent protection. However, immunity can wane over time.

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Rapid blood tests are available that can detect whether a person is immune based on the level of measles antibodies, but the tests are not 100 percent reliable. Pixabay

This has occurred even in adults with two documented doses of the vaccine, said Dr. Michael Phillips, chief epidemiologist at NYU Langone Health, which serves parts of New York City, a hot spot in the U.S. outbreak.

He said in kids, “the vaccine is really effective,” but in some adults, memory T-cells, which recognize and attack germs, do not fight the virus as effectively as they once did.

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Rapid blood tests are available that can detect whether a person is immune based on the level of measles antibodies, but the tests are not 100 percent reliable.

Adults who have any doubt about their immunity should get another dose, Schaffner said: “It’s safe. There’s no downside risk. Just roll up your sleeve.” (VOA)

Next Story

US’s Worst Measles Epidemic in 27 Years to be in Its Final Stages as No New Cases Reported

“To get to zero is tremendously encouraging,” said Jason Schwartz, a Yale University expert on vaccination policy

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File - A woman receives a measles, mumps and rubella vaccine at the Rockland County Health Department in Pomona, N.Y., north of New York City, March 27, 2019. VOA

The nation’s worst measles epidemic in 27 years could be in its final stages as a week went by with no new reported cases.

“To get to zero is tremendously encouraging,” said Jason Schwartz, a Yale University expert on vaccination policy.

The current epidemic emerged about a year ago and took off earlier this year, with most of the cases reported in Orthodox Jewish communities in and around New York City. It started with travelers who had become infected overseas but spread quickly among unvaccinated people.

In the spring, 70 or more new cases were being reported every week. Not long ago, the nation that saw that many measles cases in a whole year.

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The nation’s worst measles epidemic in 27 years could be in its final stages as a week went by with no new reported cases. Pixabay

So far this year, 1,241 cases have been confirmed — a number that didn’t rise last week, the Centers for Disease Control and Prevention reported Monday. The last time the CDC reported no new measles cases was 11 months ago.

New York officials responded to the explosion of measles cases with a wave of measures, including education campaigns to counter misinformation about vaccine safety and fines for people who didn’t get vaccinated.

The epidemic has threatened the Unites States’ nearly 2-decade-old status as a nation that has eliminated measles. The status could come to an end if the disease spreads among Americans for a year or more. Other countries, including Greece and the United Kingdom, recently lost their elimination status amid a global surge in the disease.

Measles outbreaks are typically declared over when 42 days pass without a new infection. If no new cases crop up, the national outbreak would likely end on or about Sept. 30 — just before officials might have to decide on the U.S. elimination status.

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The loss of elimination status in the U.S. could take the steam out of measles vaccination campaigns in other countries, said Dr. William Schaffner, a Vanderbilt University vaccine expert.

Health ministers around the world might say, “Why should we strive for elimination? We’ll just do the best we can to control measles, but we won’t go the extra several miles to get to zero,” Schaffner said. (VOA)