The Centers for Disease Control and Prevention on Friday said the first-known case of omicron in the U.S. was found in a person who had traveled internationally and started getting symptoms on Nov. 15.
The new timeline means omicron arrived in the U.S. earlier than originally thought. California had reported what was thought to be the first confirmed case on Dec. 1. An international traveler returned to San Francisco from South Africa on Nov. 22, developed symptoms three days later and tested positive on Nov. 29.
The CDC said 22 states have confirmed at least one omicron case, and some those cases indicate community spread is under way. Among 43 omicron patients, 33% reported international travel during the 14 days before symptom onset or testing positive, according to the CDC.
Case investigations have identified exposures associated with international and domestic travel,
large public events, and household transmission.
One vaccinated person was hospitalized for two days, but there haven’t been any deaths reported to date among the patients who have been followed by health officials, according to the CDC.
Among the cases, 58% of the patients were between 18 and 39 years of age, and 79% were fully vaccinated at least 14 days before symptom onset or testing positive. Fourteen people had received booster doses and six had recovered from previous Covid infections, according to the CDC. Five received their booster dose less than 14 days before symptom onset.
The most common reported symptoms were cough, fatigue and congestion or a runny nose.
“Many of the first reported cases of Omicron variant infection appear to be mild, although as with all variants, a lag exists between infection and more severe outcomes, and symptoms would be expected to be milder in vaccinated persons and those with previous SARS-CoV-2 infection than in unvaccinated person,” the CDC said in its weekly Morbidity and Mortality report on Friday.
The World Health Organization has said omicron appears to be more contagious than the predominant delta variant, though more data is needed for conclusive answers. White House chief medical advisor Dr. Anthony Fauci has said early reports of mild symptoms are encouraging, though more data is needed to determine the severity of disease caused by omicron.
The U.K. Health Security Agency warned on Wednesday that omicron is demonstrating a significant growth advantage over delta. Health Secretary Sajid Javid told British lawmakers that omicron infections in the U.K. could top 1 million by year end.