Hundreds of individuals may have been exposed to measles after a child with the virus visited a hospital in Northern California, according to health officials. The child, who was confirmed to have measles, was seen at UC Davis Medical Center's emergency department on March 5, potentially exposing up to 300 people.

The Sacramento County public health department stated that individuals who are unvaccinated or unsure of their vaccination status are at risk of developing measles within seven to 21 days after exposure. This incident highlights the growing concern surrounding the nationwide reemergence of measles this year. California has already reported four cases, including one in Los Angeles County involving an infectious person who visited a local Chick-fil-A restaurant after arriving on a Turkish Airlines flight.

Another recent case in San Diego County involved a 1-year-old who had traveled overseas. Other potential exposures occurred at locations such as Grossmont Pediatrics and the emergency department at Rady Children's Hospital-San Diego. Nationwide, the U.S. Centers for Disease Control and Prevention (CDC) has recorded 45 measles cases across 17 states this year, nearing the total of 58 cases reported in 2023.

Measles is highly contagious and can be transmitted through the air. The last significant year for measles in the United States was 2019 when there were 1,274 reported cases, the highest since 1992. Of the cases reported during that period, 119 required hospitalization, and 20% of those hospitalized were infants under the age of 1. Children under the age of 1 are too young to receive the measles vaccine.

The current measles outbreak in a Florida elementary school has further fueled concerns. Florida's surgeon general, Dr. Joseph Ladapo, has faced criticism for not ordering unvaccinated children to stay home during the outbreak, contrary to routine public health recommendations followed in California. Dr. Ladapo has previously drawn criticism for his statements on COVID-19 vaccines that were rebuked by CDC and FDA officials.

Vaccination remains the most effective method of preventing measles. However, declining vaccination rates, partly influenced by a discredited 1998 report linking the measles vaccine to autism, have contributed to outbreaks in the past. In response, California strengthened vaccination requirements for schoolchildren in 2015, resulting in increased measles vaccination rates among kindergartners in the state.

To prevent outbreaks, a very high percentage of the population (ideally 95% or greater) needs to be vaccinated. Measles previously afflicted California in the late 1980s to early 1990s, with over 15,000 reported cases and approximately 70 deaths. This outbreak led to recommendations for a second dose of the measles vaccine.

While some pediatricians in California have raised concerns about parents seeking delays in vaccinating their young children, vaccination rates improved nationwide with the implementation of the federal Vaccines for Children program in the 1990s, which provided vaccines to those who couldn't afford them.

Health officials in the Sacramento area are urging individuals who may have been exposed to measles to contact their healthcare providers. Symptoms typically appear seven to 14 days after exposure and include high fever, cough, runny nose, and a characteristic measles rash. The virus poses a particular danger to infants and young children.

The recommended measles vaccination schedule includes the administration of the first dose at 12 to 15 months of age, followed by a second dose at 4 to 6 years. The CDC estimates that 1 in 5 unvaccinated individuals who contract measles will require hospitalization, 1 in 20 children with measles will develop pneumonia, and 1 in 1,000 may experience life-threatening complications such as brain swelling.

It is crucial for individuals to prioritize their health by staying informed about their vaccination status and seeking medical advice if they have been exposed to measles.