A record number of measles cases is hitting the U.S. this year. Who is being affected?

The rising number of measles cases this year is by far the most since successful vaccination led to elimination of the disease in this country almost two decades ago. Cases appear in the United States every year because of people traveling abroad or visitors bringing measles from other countries where it is still common. Lower rates of vaccination, however, have created increased risk when the virus is brought in from other countries.

At least 839 cases across 23 states have been reported this year, according to the Centers for Disease Control and Prevention.

Two overlapping groups have suffered the most this year: children under age 4 and people who were unvaccinated.

Breakdown of 2019 cases

BY AGE

27

25

68

76

167

203

138

0-6

months

6-11

mo.

12-15

mo.

16 mo.

to

4 years

5-19

20-49

50+

BY VACCINATION STATUS

503 people who contracted

measles were unvaccinated

125 unknown

76 people had been

previously vaccinated

BY AGE

27

25

68

76

167

203

138

0-6

months

6-11

mo.

12-15

mo.

16 mo.

to 4 years

5-19

20-49

50+

BY VACCINATION STATUS

503 people who contracted

measles were unvaccinated

125 unknown

76 people had been

previously vaccinated

BY VACCINATION STATUS

BY AGE

503 people who contracted

measles were unvaccinated

125 unknown

25

68

76

167

203

138

27

76 people had been

previously vaccinated

0-6

months

6-11

mo.

12-15

mo.

16 mo.

to 4 years

5-19

20-49

50+

Note: Cases reported as of Friday, May 3.

The vast majority of people infected have not been vaccinated. Communities with lower vaccination rates are vulnerable because measles spreads so quickly through coughing and sneezing.

More than 10 percent of the people with measles this year, however, had been vaccinated. If people are vaccinated but exposed to measles, they may still become infected.

The first of the two-dose vaccination is often given to children around 12 months old. One dose of the vaccine is 93 percent effective, according to the CDC, and two doses are 97 percent effective in preventing infection. That still means that some people will not be protected.

Measles cases by county

100

200

350

10

Location approximate

WASH.

N.H.

ORE.

N.Y.

MASS.

MICH.

CT

PA.

IOWA

N.J.

NEV.

IND.

MD.

ILL.

COLO.

MO.

KY.

CALIF.

TN.

ARIZ.

GA.

TEXAS

FLA.

100

200

350

Location approximate

10

WASH.

Portland

N.H.

ORE.

N.Y.

Rockland Co.

MICH.

MASS.

CT

Detroit

—New

York

PENN.

IOWA

N.J.

NEV.

IND.

MD.

Denver

San

Francisco

ILL.

COLO.

MO.

KY.

CALIF.

TN.

Los

Angeles

ARIZ.

GA.

Dallas

TEXAS

Houston

FLA.

100

200

350

Location approximate

10

WASH.

Portland—

N.H.

ORE.

N.Y.

Rockland Co.

MICH.

MASS.

CT

Detroit

Chicago

—New

York

IOWA

PENN.

N.J.

NEV.

ILL.

IND.

MD.

San

Francisco

Denver

COLO.

MO.

KY.

CALIF.

TN.

Los Angeles

ARIZ.

Atlanta area

GA.

Dallas

TEXAS

Houston

FLA.

100

200

350

Location approximate

10

WASH.

Portland—

N.H.

ORE.

N.Y.

MICH.

MASS.

Orange Co.

CONN.

Detroit

—Rockland Co.

Chicago

—New York

PENN.

IOWA

—Ocean Co.

N.J.

NEV.

Baltimore

ILL.

IND.

MD.

San

Francisco

Denver

COLO.

CALIF.

MO.

KY.

Eastern Tenn.

TN.

Los Angeles

ARIZ.

Atlanta area

GA.

Dallas

TEXAS

Houston

FLA.

Note: Cases reported as of Friday, May 3.

Travel can spread measles quickly from one community to another. A child who flew to the United States from Israel brought measles into Brooklyn, public health officials said, and then an infected member of that community drove to Michigan, creating an outbreak there. Outbreaks have also branched out from Brooklyn to other parts of New York, Connecticut and Baltimore County. An outbreak in New Jersey may also be related.

Measles cropped up in Los Angeles this year after a traveler brought it home from Vietnam. Then a second traveler brought it from Thailand. California’s largest outbreak — near Sacramento — came from a visitor to the Philippines, according to state health officials.

A historic number of cases in decades

1958

763k

27,782

1963

vaccination

begins

DETAIL

0

1950

Measles declared

eliminated

2,126

667

839

0

1990

’92

2000

2014

2019

27,782

1958

763k

1963

vaccination

begins

DETAIL

0

1950

Measles declared

eliminated

2,126

667

839

0

1990

’92

2000

2014

2019

27,782

1958

763k

1963

vaccination

begins

Measles declared

eliminated

2,126

667

839

DETAIL

0

0

1990

’92

2000

2014

2019

1950

Before the measles vaccine was introduced in 1963, experts estimate the country had millions of cases every year, so many that the vast majority were never reported. Each year about 500 people died, and many suffered lifelong impacts, such as breathing problems. Vaccination quickly led to a decline in cases and deaths, and in 2000 the disease was declared eliminated. This year has had the greatest number of cases since an outbreak from 1989 to 1991 caused more than 50,000 cases.

Where parents don’t have to immunize their children

PHILOSOPHICAL

ME

WI

AK

VT

NH

WA

ID

MT

ND

MN

IL

MI

NY

MA

OR

NV

WY

SD

IA

IN

OH

PA

NJ

CT

RI

CA

UT

CO

NE

MO

KY

WV

VA

MD

DE

AZ

NM

KS

AR

TN

NC

SC

DC

HI

OK

LA

MS

AL

GA

TX

FL

RELIGIOUS

ME

WI

AK

VT

NH

WA

ID

MT

ND

MN

IL

MI

NY

MA

OR

NV

WY

SD

IA

IN

OH

PA

NJ

CT

RI

CA

UT

CO

NE

MO

KY

WV

VA

MD

DE

AZ

NM

KS

AR

TN

NC

SC

DC

HI

OK

LA

MS

AL

GA

TX

FL

PHILOSOPHICAL

RELIGIOUS

ME

ME

WI

AK

WI

AK

VT

NH

VT

NH

WA

ID

MT

ND

MN

IL

MI

NY

MA

WA

ID

MT

ND

MN

IL

MI

NY

MA

OR

NV

WY

SD

IA

IN

OH

PA

NJ

CT

RI

OR

NV

WY

SD

IA

IN

OH

PA

NJ

CT

RI

CA

UT

CO

NE

MO

KY

WV

VA

MD

DE

CA

UT

CO

NE

MO

KY

WV

VA

MD

DE

AZ

NM

KS

AR

TN

NC

SC

DC

AZ

NM

KS

AR

TN

NC

SC

DC

HI

OK

LA

MS

AL

GA

HI

OK

LA

MS

AL

GA

TX

FL

TX

FL

PHILOSOPHICAL

RELIGIOUS

ME

ME

WI

AK

WI

AK

VT

NH

VT

NH

WA

ID

MT

ND

MN

IL

MI

NY

MA

WA

ID

MT

ND

MN

IL

MI

NY

MA

OR

NV

WY

SD

IA

IN

OH

PA

NJ

CT

RI

OR

NV

WY

SD

IA

IN

OH

PA

NJ

CT

RI

CA

UT

CO

NE

MO

KY

WV

VA

MD

DE

CA

UT

CO

NE

MO

KY

WV

VA

MD

DE

AZ

NM

KS

AR

TN

NC

SC

DC

AZ

NM

KS

AR

TN

NC

SC

DC

HI

OK

LA

MS

AL

GA

HI

OK

LA

MS

AL

GA

TX

FL

TX

FL

Note: Washington State has passed a bill removing personal and philosophical exemptions for the MMR vaccine only. It is waiting for signature by Gov. Jay Inslee (D).

Parents in 17 states can opt out of vaccinating their children if they cite personal or philosophical objections. All states have medical exemption laws since some people cannot be vaccinated because of health issues, such as weakened immune systems. Almost all states grant religious exemptions for people who have religious beliefs against immunization.

Dan Keating

Dan Keating analyzes data for projects, stories, graphics and interactive online presentations.

Brittany Renee Mayes

Brittany Renee Mayes joined The Washington Post as a general assignment graphics reporter in June 2018. She previously worked at NPR on the visuals team as a news applications developer.

Tim Meko

Tim Meko designs and develops maps, data visualizations and explanatory graphics. Before coming to The Post, he led the visuals team at the Urban Institute and was an infographics artist at the Columbus Dispatch.

About this story

Data from state and county health departments, media reports, the National Conference of State Legislatures and the CDC. Total count of cases as of May 10.

Originally published May 6, 2019.

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