A syringe is filled with a dose of Pfizer’s COVID-19 vaccine at a pop-up community vaccination center at the Gateway World Christian Center in Valley Stream, New York, US, February 23, 2021. (Reuters photo)

The new highly transmissible omicron coronavirus variant has been found in at least 10 new American states, a sign that the virus is spreading fast throughout the country.

Omicron has been found in the states of Maryland, Utah, Missouri, Pennsylvania, New York, Colorado, Minnesota, California, Hawaii and Nebraska, reports said on Friday.

Most of these states have found cases of the coronavirus variant among patients who were fully vaccinated and developed mild symptoms, while some reported cases with unvaccinated persons.

US officials are concerned that the new variant will also be found in other states.

The first case was found on Wednesday in San Francisco, where the patient had returned from South Africa days before the omicron variant was discovered there.

The second case was found in Minnesota, but the patient only recently traveled to New York. The patient developed symptoms on November 22, a week before the travel ban took effect, proving that the strain was already in America.

The discovery triggered fears across the nation over the impact of the Omicron variant, which was first reported in South Africa last month and has since spread to at least two dozen countries.

Scientists are still working to answer many questions about the new variant, including how transmissible it is and how effective the vaccines are against it.

The World Health Organization (WHO) designates Omicron a variant of concern, warning that the new strain poses a very high global risk.

The White House plans to announce stricter testing rules for international visitors.

Airlines in the US were ordered to disclose passenger names and other information about those who have recently been in eight southern African countries, according to documents seen by Reuters.

Chief White House medical adviser Anthony Fauci urged Americans to get vaccinated against COVID-19.

On Thursday, President Joe Biden announced his plan to fight the Omicron and Delta coronavirus variants over the winter, while warning that infections will rise this winter.

Among the measures are free and insurer-funded at-home COVID-19 testing and new requirements for international travelers.