In the first quarter of 2024, the United States has witnessed a significant surge in measles cases, posing a renewed threat to the country's elimination status, according to a report released by the Centers for Disease Control and Prevention (CDC). Measles, which had been considered eliminated in the U.S. since 2000, has seen a resurgence in recent years, and the current spike in cases highlights the need for increased vaccination coverage.

From January to March this year, the U.S. recorded a total of 97 measles cases, accounting for approximately 30% of the total cases reported since the beginning of 2020. This significant increase in cases compared to previous years can be attributed in part to the impact of the COVID-19 pandemic, which resulted in fewer in-person interactions and subsequently reduced measles transmission.

The report emphasizes that the rising number of cases during the first quarter of 2024 poses a renewed threat to the elimination of measles in the U.S. The country almost lost its elimination status in 2019 when it witnessed over 1,200 cases, largely due to outbreaks in Orthodox Jewish communities in New York. The current high case load, with seven outbreaks and 113 cases reported as of April 4, creates uncertainty around the maintenance of elimination status.

The CDC report highlights the importance of widespread vaccination coverage to combat the spread of measles. It reveals that approximately 91% of recorded measles cases since January 2020 were reported among unvaccinated individuals or those with an unknown vaccination status. The report underscores the effectiveness of the measles, mumps, and rubella (MMR) vaccine, with one dose offering 93% protection and two doses providing 97% protection against measles.

Disturbingly, 83% of recorded cases this year have been in individuals who were unvaccinated or had an unknown vaccination status. Furthermore, half of the cases reported in 2024 are among children under the age of five, with 65 people already hospitalized. Fortunately, no deaths due to measles have been reported in the past four years.

The decline in measles vaccination rates in recent years is a concerning factor. The CDC report reveals that 12 states and Washington, D.C., had vaccination rates below 90% during the 2022-23 school year. To prevent sustained transmission, communities should aim for vaccination coverage around 95%. However, the share of U.S. kindergartners receiving two doses of the MMR vaccine dropped from 95% in the 2019-20 school year to 93% in the 2022-23 school year. This leaves approximately 250,000 kindergartners susceptible to measles annually.

Notably, vaccination coverage has also declined globally. The CDC reports a decrease in global measles vaccine coverage from 86% in 2019 to 83% in 2022, with a further decline to 81% during the COVID-19 pandemic, the lowest since 2008.

To address the issue, the CDC urges vaccination before international travel, as most measles cases introduced to the U.S. originate from other countries. The number of countries reporting "large or disruptive" measles outbreaks increased by 123% between November 2022 and October 2023.

In the U.S., the largest measles outbreak this year started at a migrant shelter in Chicago, leading to a total of over 60 cases in the city. The Chicago Department of Public Health has taken measures to contain the spread, distributing over 13,000 measles vaccines since last month.

Measles remains highly contagious, with an infected person capable of spreading the disease to up to 90% of close contacts who lack immunity. However, the CDC report assures that the risk of widespread measles transmission in the U.S. remains low due to high population immunity.

In light of the recent surge in measles cases, it is imperative for individuals to ensure they are up to date on vaccinations and for communities to strive for higher vaccination coverage. Sustained efforts in immunization are crucial to safeguard public health and maintain the elimination of measles in the United States.