US experiences a second wave of measles this year as outbreak speeds up in South Carolina

Measles Cases Surge in the U.S.

As several measles outbreaks continue across the United States, the number of cases is rising rapidly, reminiscent of when the West Texas outbreak peaked earlier this spring.

In the past week alone, there have been 84 new measles cases reported nationwide, according to data from the US Centers for Disease Control and Prevention. This marks the highest weekly total since April, when about 100 new cases were being reported each week.

Interestingly, Texas has not reported new cases since mid-August, when officials declared its outbreak over.

However, South Carolina is seeing a sharp increase in cases, with state health officials reporting that over 250 individuals are in quarantine due to potential exposure, and 16 of those are sick and in isolation. Some of these individuals are undergoing quarantine for a second time, according to state epidemiologist Dr. Linda Bell, as they hadn’t received adequate protection through vaccination or natural immunity after their first exposure.

Dr. Bell noted, “The maximum incubation period for measles is 21 days, so if anyone has to go through quarantine twice, that’s a considerable interruption.” She emphasized that vaccination remains the most effective way to prevent the disruptions measles can cause in education and employment.

Cases are ramping up quickly in South Carolina, reflecting a concerning trend.

While overall compliance with quarantine measures is good, Dr. Bell identified several contributing factors to this surge, including holiday gatherings, travel, and lower-than-expected vaccination rates for such a highly contagious virus.

Since the outbreak began in October, South Carolina has reported 111 measles cases, with at least 105 occurring in individuals who had not received a dose of the measles-mumps-rubella (MMR) vaccine. The two-dose vaccine is recommended for children and provides 97% protection against measles.

The majority of cases have been in the upstate region around Greenville, with many recent infections linked to an exposure at a church. Schools and healthcare facilities have also seen cases.

Dr. Bell pointed out, “Most of our cases come from exposures in familiar settings. However, with each new case in a population with low vaccination rates, the potential for further transmission increases, given the virus’s high infectivity.” She underscored the importance of increasing vaccination coverage to mitigate the spread.

Other states, like Utah and Arizona, are also witnessing rising measles cases. Arizona reported 176 cases as of Tuesday, the second-highest in the year, while Utah had 115 cases.

This year is shaping up to be a record one for measles in the U.S. Between January and July, nearly 1,300 cases have been documented—surpassing any other year since the disease was declared eliminated in the U.S. 25 years ago.

Currently, more than 1,900 cases have been recorded this year, with the majority affecting individuals who were unvaccinated. If the outbreaks extend into January, the U.S. risks losing its elimination status, similarly to what happened to Canada recently.

According to the CDC, there have been 47 outbreaks in the U.S. this year, a nearly threefold increase compared to last year. An outbreak is defined as three or more related cases.