2000 – United States declares measles eliminated – The U.S. officially attains measles‑elimination status, meaning no continuous transmission for ≥12 months, a benchmark later used to assess future outbreaks[4].

1992 – Last year the U.S. recorded >2,000 measles cases before the 2025 surge – The 1992 epidemic prompts later public‑health officials to compare the 2025‑2026 resurgence with historic levels[11].

2010‑2011 – Non‑medical exemption rate averages 0.6 % among kindergartners – A JAMA analysis later shows this baseline, highlighting how exemptions have risen dramatically since then[8].

2014 – Spartanburg County non‑medical exemptions sit at 2 % – The county’s exemption rate later climbs to 8 % by 2024, underscoring a growing vulnerability in the outbreak’s epicenter[8].

2024‑25 school year – Spartanburg County school‑age measles vaccination drops to ~90 % – The decline below the 95 % herd‑immunity threshold helps explain why the outbreak spreads rapidly in the Upstate region[2][10].

2024‑25 – National kindergarten MMR coverage falls to 92.5 % – CDC data show coverage below the 95 % target, a shortfall linked to rising exemptions and later outbreaks across the country[6][14].

Oct 2025 – South Carolina declares a measles outbreak – State health officials announce the outbreak after the first cases appear in the fall, triggering intensified contact‑tracing and vaccination outreach[10].

Jan 20 2025 – First measles case identified in West Texas (Gaines County) – The rash appears on this date, marking the start of the largest Texas surge that later reaches 762 cases and two child deaths[14].

Aug 2025 – West Texas outbreak declared over after 762 cases and two deaths – The outbreak ends in mid‑August, but data gaps leave many suspected cases unconfirmed[14].

Nov 2025 – Pan American Health Organization (PAHO) determines Canada has lost measles‑elimination status – The decision highlights regional vulnerability and adds pressure on the U.S. to retain its status[11].

Dec 30 2025 – United States records 2,065 confirmed measles cases, the highest annual total since 1992 – Cases span 43 states and 49 separate outbreaks, reviving concerns about national immunity[24].

Jan 8 2026 – Spartanburg County reports >200 measles infections; vaccination coverage fell from 95 % to 90 % – Pediatrician Stuart Simko describes the patients as “very sick” with high fevers, while officials note the outbreak likely began in a Ukrainian immigrant community with low uptake[10][1].

Jan 8 2026 – Ohio confirms its first 2026 measles outbreak (three unvaccinated children) – Dr. Vanderhoff stresses that “measles remains a serious, yet preventable disease” and urges vaccination[18].

Jan 9 2026 – U.S. seeks to retain measles‑elimination status; WHO’s 12‑month rule emphasized – Officials argue current South Carolina and other clusters are not linked to the Texas outbreak, a distinction crucial for PAHO’s upcoming review[9].

Jan 10 2026 – South Carolina family’s holiday travel spreads measles to Washington state – Exposure sites across three cities lead to local cases, prompting health alerts about the disease’s high contagion[23].

Jan 14 2026 – JAMA study documents rise in non‑medical exemptions to >3 % nationally (2023‑2024) – The analysis notes 53.5 % of counties saw at least a 1 % increase, with Spartanburg County reaching 8 % in 2024, fueling the local outbreak[8].

Jan 15 2026 – Early‑2026 U.S. measles surge reaches 171 cases in the first weeks – The surge is driven by upstate South Carolina and the Utah‑Arizona corridor, complicating exposure tracking as cases may be infectious before symptoms appear[7].

Jan 16 2026 – Snohomish County, WA adds three cases linked to the visiting South Carolina family – Health officials warn more cases are likely and urge vaccination checks, noting “most residents have immunity, risk low”[22].

Jan 20 2026 – PAHO schedules April 13 meeting to decide U.S. measles‑elimination status – The review will consider whether a single transmission chain has persisted for 12 months; the same day, CDC reports 2,144 cases nationwide and a national vaccination rate of 92.5 %[14][21].

Jan 20 2026 – CDC deputy director Dr. Ralph Abraham downplays loss of elimination status – He says it “would not be a grave development” and stresses that vaccination remains the most effective prevention, while the agency stays “open for business”[6].

Jan 21 2026 – CDC principal deputy director Demetre Daskalakis calls the South Carolina outbreak “very, very active” – He warns the situation is “far from under control” and attributes rapid spread to distrust in vaccines[6].

Jan 27 2026 – South Carolina measles cases top 789, the largest U.S. surge since 2000 – The outbreak includes 18 hospitalizations, 557 quarantines, and over 700 unvaccinated patients; HHS pledges $1.4 million despite Secretary Robert F. Kennedy Jr.’s mixed messaging on vaccines[4].

Jan 30 2026 – South Carolina reports 847 infections, with some schools’ vaccination rates as low as 20 % – Pediatrician Simko reiterates that patients are “very sick,” Senator Josh Kimbrell calls for limits on unvaccinated individuals, and mobile clinics vaccinate 62 people since October[1].

Feb 5 2026 – Jalisco, Mexico imposes a 30‑day school mask mandate amid a surge of 1,163 confirmed measles cases – Officials warn the upcoming 2026 FIFA World Cup could amplify transmission, especially in high‑hesitancy Mennonite communities[13].

Feb 21 2026 – South Carolina outbreak reaches 973 cases, the nation’s largest in 2026 – Hospitals report only 20 admissions (≈2 % of cases), physicians label the figure “ludicrous” as severe complications are likely undercounted, and a pending bill would restrict doctors from challenging vaccine refusals[3].

Apr 13 2026 – PAHO convenes to determine whether the United States retains measles‑elimination status – The decision hinges on whether any transmission chain has persisted for a full year, a judgment that will shape U.S. public‑health policy and international standing[14].