As initial shipments of COVID-19 vaccines arrive throughout the United States this week and in coming weeks, Dr. Yvonne Maldonado, a Stanford professor who serves on the Western States review panel for the COVID-19 vaccines, envisions the general population could receive the vaccine by spring or summer.

Under the federal rollout plan, Phase 1A calls for the country's estimated 20 million health care workers and 3 million residents of long-term-care facilities to be vaccinated; Phase 1B covers essential workers; Phase 1C will cover the roughly 80 million people who are 65 years and older with underlying medical conditions that make them vulnerable for severe illness from the coronavirus.

Maldonado said that while the nation's current allocation of 100 million doses of the vaccines might seem plentiful, "We do not think that is enough."

If the nation's nearly 330 million people are to receive two doses each, which is necessary to reach 94% or 95% immunity, the country would need about three quarters of a billion doses. Not everyone would want the vaccine, Maldonado noted, but the point is that they should be able to get it should they choose to.

The government is currently in negotiations to purchase more doses. Any hitches that might slow availability of the vaccines would likely be on the manufacturing side.

"The supply chain might be an issue," she said.

Maldonado, who is also a liaison to the U.S. Centers for Disease Control and Prevention's Advisory Committee on Immunization Practices, said Wednesday that she expected the CDC's review of Moderna Inc.'s vaccine on Thursday, Dec. 17, to be more streamlined than it was for the Pfizer-BioNTech vaccine.

On Thursday, the FDA's Center for Biologics Evaluation and Research's Vaccines and Related Biological Products Advisory Committee recommended the emergency use authorization of Moderna's vaccine or anyone 18 years and older by a vote of 20 in favor and one abstention.

"If things go well tomorrow, by Saturday or Sunday we could have the votes from the CDC and allocate the Moderna vaccine for Phase 1B health care workers. Shortly thereafter, in February, first responders and other essential workers could receive the vaccine," she said.

More vaccines could be in the pipeline in 2021 beyond Pfizer and Moderna, she said. Johnson & Johnson's vaccine clinical trials, which tested 30,000 people, including at Stanford, will be completed at the end of this year and could be approved in early 2021.

Astrazeneca's vaccine is also undergoing trials and could be available in 2021. Two others, by Novavax and Sanofi, are also in process. Technical issues with the Sanofi vaccine could delay the start of its trials until February, she said.

Maldonaldo said that, having extensively reviewed the data on the Pfizer and Moderna vaccines, the most remarkable thing she noticed is the companies' transparency about their data. Based on that data, the vaccines "do look very safe," she said.

At Stanford, many of Maldonado's colleagues are excited about the vaccines. They think the vaccines are "an opportunity to really stem this pandemic," she said.

Find comprehensive coverage on the Midpeninsula's response to the new coronavirus by Palo Alto Online, the Mountain View Voice and the Almanac here.