"It'll be better if we get more people their first doses and get them fairly protected with their first doses. If the cost is you're a week or two late in your second dose... there really isn't any evidence that's going to cause any harm," said Dr. Wachter.
Luz Pena: "Some counties are holding vaccines for people who have appointments to get that second dose. Should they be doing that?"
Dr. Bob Wachter: "I have felt all along that we are being a little too rigid about the second dose."
Dr. Wachter is calling for counties to be flexible at least for the next three months as vaccine supply increases across the country.
VACCINE TRACKER: Here's how CA is doing, when you can get a coronavirus vaccine
Pfizer and Moderna suggest you get the second dose 3-4 weeks after the first dose, but he argues counties can wait even longer to schedule those appointments.
"10 days after the second dose you're 95% protected but it turn out that before you get your second dose, like the day before, you're already about 80-90% protected," said Dr. Wachter.
In the UK they've prioritized first doses, "This is the approach the United Kingdom has taken. They are delaying the second doses for a couple of months," said Dr. Wachter.
Luz Pena: "Did Pfizer and Moderna say 3-4 weeks because they wanted to expedite the process to get authorization from the FDA?"
Dr. Wachter: "Yeah, they had to pick a time and it's a reasonable time. Yes, part of this was to expedite it. They didn't want to wait 2, 3, 4 months after the first dose"
Stanford's Infectious disease specialist Dr. Dean Winslow says more data needs to be collected, but he points to the Hepatitis B vaccine as an example of a longer timeline.
"That requires 3 doses. Times 0 and 4 to 6 weeks later and then six months later," Dr. Dean Winslow.
VIDEO: COVID-19 variants found in UK, Brazil now detected in Bay Area
We went to UCSF's Quantitate Biosciences Institute for answers.
"The world is essentially a petri dish and it's an amazing and yet frightening experiment that is ongoing with this virus," said Dr. Nevan Krogan, director of the UCSF's Quantitate Biosciences Institute.
This is where they study the mutating genes of the variants. At least three have been detected in the Bay Area.
"It's interesting because all the variants are mutating in the same proteins," said Lorena Zuliani-Alvarez, Science Project Manager for the QCRG Coronavirus Research Consortium.
RELATED: Bay Area COVID-19 tracker
Dr. Nevan Krogan says the longer we wait to vaccinate as many people as possible, the more time the virus has to mutate.
"These viruses that are more transmissible will soon become the dominant virus here and around the world," said Dr. Krogan.
As to the importance of getting the second dose as it becomes available, "You absolutely, absolutely need the second dose because the second dose brings you up to a higher level of immunity," said Dr. Wachter.
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