About 41 West Virginian patients who earlier received the Regeneron monoclonal antibody treatment instead of the Moderna vaccine ultimately got their first shot of a vaccine Thursday, the West Virginia National Guard told ABC News.

The patients were among the 44 people who were identified on Dec. 31 as receiving the wrong treatment at a vaccination clinic hosted by staff at the Boone County Health Department.

The National Guard did not say which vaccine those patients received when they got the correct shot.

Their first shots come despite recommendations by the U.S. Centers for Disease Control and Prevention that patients who receive monoclonal antibodies or convalescent plasma should defer vaccinations for at least 90 days.

-ABC News' Arielle Mitropoulos contributed to this report

Pfizer and its partner BioNTech have plans to begin offering their COVID-19 vaccine to clinical trial volunteers who received placebo by March 1, several months earlier than initially planned, STAT reported.

The FDA and its advisers had pushed hard for volunteers to remain on placebo as long as possible to gather more safety and efficacy data about the vaccines, while the companies argued that volunteers should receive the vaccines sooner for both ethical and practical reasons.

-ABC News' Eric M. Strauss

New York state saw 166 deaths Thursday -- the highest number of deaths in a single day since May 12.

On Thursday, 219,523 test results were reported to New York state, and 7.52% were positive, New York Gov. Andrew Cuomo's office reported.

There were 7,886 patient hospitalizations statewide, 1,292 patients in intensive care units and 776 intubated.

-ABC News' Joshua Hoyos

340,000 people have been vaccinated to date in Texas, out of the state's received allotment of 786,000 vaccination doses, according to data from Texas Health and Human Services.

Houston Mayor Sylvester Turner also authorized the Houston Health Department to open the city's first free COVID-19 vaccination clinic on Jan. 2. The clinic will expand vaccine access to the general public at high risk of severe illness and death from coronavirus disease, according to a statement from Texas health officials.

Texas' health department received its first allotment of 3,000 doses of the Moderna vaccine and started administering it on December 28.

The Houston Health Department will announce additional free vaccination opportunities as supply increases.

-ABC News' Gina Sunseri

Public Health England does not recommend mixing COVID-19 vaccines from different suppliers, according to the agency's head of immunizations, Dr. Mary Ramsay.

"We do not recommend mixing the COVID-19 vaccines -- if your first dose is the Pfizer vaccine you should not be given the AstraZeneca vaccine for your second dose and vice versa," Ramsay said in a statement Saturday. "There may be extremely rare occasions where the same vaccine is not available, or where it is not known what vaccine the patient received. Every effort should be made to give them the same vaccine, but where this is not possible it is better to give a second dose of another vaccine than not at all."

The clarification comes amid questions over the British government's updated guidance on COVID-19 vaccines, which now says that if individuals who received the first shot go to an immunization site where that same vaccine is not available for a second shot, or if the first vaccine received is unknown, "it is reasonable to offer one dose of the locally available product to complete the schedule."

"This option is preferred if the individual is likely to be at immediate high risk or is considered unlikely to attend again," the guidance adds.

The guidance, which was updated Thursday, also notes that "there is no evidence on the interchangeability of the COVID-19 vaccines although studies are underway," and thus "every effort should be made to determine which vaccine the individual received and to complete with the same vaccine."

Next week, the United Kingdom is set to begin distribution of a COVID-19 vaccine developed by England's University of Oxford and manufactured by British-Swedish pharmaceutical giant AstraZeneca, after the drug was approved Wednesday for emergency supply. Another COVID-19 vaccine developed by U.S. pharmaceutical giant Pfizer and its German partner BioNTech was approved in the U.K. on Dec. 2 and rollout began a week later.

ABC News' Zoe Magee contributed to this report.