A national measles outbreak, including more than 500 cases in New York City since September 2018, has generated concern. The vast majority of the city’s measles cases have been reported in the Orthodox Jewish communities in Williamsburg, Brooklyn, but two children who attend school in Sunset Park, Brooklyn, became the first reported cases of measles in the city’s public schools on May 7. School officials informed families that the two students, who were unvaccinated, were not in school while infectious.

New York City declared a public health emergency in April following the outbreak and the city health commissioner now requires individuals living and working in zip codes 11205, 11206, 11211 and 11249 to receive the Measles-Mumps-Rubella vaccine or face fines of up to $1,000.

Measles, which is highly contagious, was declared eliminated in 2000 thanks to an effective and safe vaccination program, but it has re-emerged among unvaccinated children and adults.

Measles can cause severe complications such as pneumonia, encephalitis (swelling of the brain) and death. The preventative measles vaccine, which is typically administered over two doses at ages 1 and 4, provides lifelong protection.

This Q&A from the New York City Department of Health answers some of the most common questions.

What is measles?

Measles is a highly contagious virus that causes fever, rash, cough, runny nose and red, watery eyes. The rash starts on the face and spreads to the rest of the body two to four days after the other symptoms begin. It can spread to others through coughing and sneezing and remains active and contagious in the air and on surfaces for up to two hours.

How do I know if I am at risk of getting measles?

Speak with your physician about whether you are immune to measles. If you previously had two doses of a measles-containing vaccine, have laboratory documentation of prior measles infection or were born before 1957, you are considered immune. Your healthcare provider can order a blood test, called a serology, to see if you are immune to measles.

Who has a higher risk of exposure?

Healthcare workers, first responders and laboratory workers working with clinical specimens are at a higher risk.

What if I live or work in Williamsburg?

If you live or work in zip codes 11205, 11206, 11211 or 11249, you are required to have the Measles-Mumps-Rubella (MMR) vaccine to stop the spread of measles. People who can demonstrate an immunity to measles or have a medical condition that prevents them from receiving the vaccine will not need to get vaccinated. We encourage you to check your immunization records or talk to your health care provider to confirm your vaccination history or immunity status.

What if someone who has measles comes to my workplace?

Without confirmation by a physician, there is no way to know if someone has measles. If a person is confirmed by a physician to have measles, the city Department of Health will follow up with the person and also with their contacts. Those who have immunity are unlikely to become sick from casual contact with a person who has the measles.

Do workers need to be monitored for symptoms?

You should self-monitor and report symptoms to your employer, especially if you are serving the communities experiencing the current outbreak. Stay home from work if you feel sick.

When is someone contagious?

An infected person can spread measles to others from four days before through four days after the rash appears.

How should I protect myself?

The best way is to verify that you and your family members have received two doses of the MMR vaccine. If you are unsure, get vaccinated. Consult with your physician if you are pregnant or are immune-compromised. People who are unvaccinated risk getting sick and also spreading measles to people who cannot be vaccinated for medical reasons.

If I conduct home visits as part of my work duties, am I at risk?

You have very little risk if you are immune. As a precaution, if you are working in a community experiencing an outbreak of measles, you should ask if anyone in the home is ill before entering. If yes, you should contact your supervisor and reschedule your home visit.

Can I bring measles home to my family?

The measles virus can survive in the air and on surfaces for about two hours. You should practice good hand hygiene by washing your hands with soap and plenty of warm water for a minimum of 20 seconds. Use hand sanitizer containing alcohol to clean your hands when soap and water are not available. Be sure to wash your hands and face at the conclusion of your workday.