South Carolina tops Texas measles outbreak record—with no end in sight

A significant measles outbreak is unfolding in South Carolina, with the state’s Public Health Department reporting 789 cases as of its latest update. The highly contagious nature of the virus, coupled with exposures in both school and public settings, is driving a surge in quarantines and raising concerns about further spread.

Understanding the Threat

Measles is exceptionally infectious. The virus can remain airborne in a room for up to two hours after an infected person has left. Among individuals who are not vaccinated and are exposed, up to 90 percent will become ill. A key challenge in controlling the outbreak is that individuals can be contagious for four days before the characteristic rash appears, facilitating undetected transmission.

Did You Know? The measles virus can linger in the air for up to two hours after an infected person is no longer present.

Widespread Exposure

The outbreak has impacted 23 schools across the state. In 20 of these schools, unvaccinated and exposed students have been identified and placed in quarantine, with the number of students quarantined at individual schools ranging from 13 to 59. Officials are still working to determine the number of students needing quarantine in the remaining three schools.

Exposure isn’t limited to schools. State officials have identified eight public places where recent measles exposures have occurred, including grocery stores, a US Post Office, and a skating center. Currently, 557 students are under quarantine, but the potential for additional exposures remains.

Expert Insight: The high rate of susceptibility, combined with the virus’s ability to spread before symptoms are obvious, creates a complex public health challenge. The situation underscores the importance of understanding transmission dynamics and implementing effective control measures.

Vaccination and Protection

Data from the 789 cases reveals a strong correlation between vaccination status and infection. 97 percent of those infected – 769 individuals – were either unvaccinated, partially vaccinated, or had an undocumented vaccination status. The measles, mumps, and rubella (MMR) vaccine is highly effective, providing 97 percent protection against measles with two doses, and this protection is considered lifelong.

What Could Happen Next

Given the current trends, case numbers could continue to rise. Further spread is likely if vaccination rates do not improve and if exposures continue to occur in schools and public places. It is possible that quarantine numbers will increase as officials identify additional exposed individuals. The length of the outbreak is uncertain, but it could persist as long as susceptible individuals remain and the virus continues to circulate.

Frequently Asked Questions

How long can someone spread measles before they know they are sick?

A person can be infectious for four days before the measles rash develops.

What percentage of cases involved individuals with an unknown or incomplete vaccination record?

97 percent of the 789 cases were unvaccinated or partially vaccinated or had an undocumented vaccination status.

How effective is the MMR vaccine?

Two doses of the measles, mumps, and rubella vaccine are 97 percent effective against measles, and that protection is considered lifelong.

What steps do you think communities can take to address vaccine hesitancy and protect public health?