The number of measles cases in the U.S. has surpassed the record-breaking tally for all of 2025, with five more months of 2026 still to come.\n<\/p>\n
The U.S. Centers for Disease Control and Prevention logged 2,318 cases of measles as of Thursday, according to an agency update on Friday.\n<\/p>\n
The nation had 2,289 cases in 2025, the worst year for measles in\u00a0more than three decades<\/a>. Now, 2026 has easily become the U.S.\u2019s worst year for measles since 1991, as major outbreaks in South Carolina, Utah and Arizona have sickened hundreds and smaller clusters of cases sparked in other states.\n<\/p>\n In November, international health officials will meet to determine if the U.S. and Mexico have\u00a0lost their measles-free status<\/a>. The U.S. eliminated local measles spread in 2000 by maintaining high vaccination rates, which have fallen in recent years to\u00a0below the 95% coverage<\/a>\u00a0needed to prevent outbreaks.\n <\/p>\n Measles cases are undercounted<\/p>\n While measles cases in the U.S. are climbing, it may be impossible to say exactly how far-reaching the spread is. Public health departments and disease researchers have long acknowledged that official counts are incomplete, because some people get sick and don\u2019t seek out treatment \u2014 something not unique to measles.\n<\/p>\n Furthermore, experts say the spread might be greater than what\u2019s known because the virus is one of the most contagious known to medicine and vaccination rates nationwide have declined. National vaccination rates for measles, mumps and rubella \u2014\u00a0which dropped to 92.5%<\/a>\u00a0among kindergartners in the 2024-25 school year, from 95.2% in 2019-20 \u2014 obscure even lower rates in certain communities.\n<\/p>\n In Utah, where public health officials have fought measles\u00a0for more than a year<\/a>, the virus has sickened more than 700 people during that time, according to the\u00a0state health department<\/a>. Experts relying on mathematical modeling and genetic analyses indicate that a large outbreak on the Utah-Arizona border could be around three to four times bigger than what\u2019s currently known, state epidemiologist Dr. Leisha Nolen said.\n<\/p>\n The picture is muddier in South Carolina, which had\u00a0the nation\u2019s largest outbreak in 35 years<\/a>. There, the 997 total is likely an undercount, the state health department has said, but it doesn\u2019t know by how much.\n<\/p>\n Dr. Brannon Traxler, acting director of the state department of health, said the undercount is \u201cimpossible to know and may vary during the course of an outbreak.\u201d\n<\/p>\n