Cell biologist and Exploratorium "After Dark Online" host Jennifer Frazier joins Dr. Kirsten Bibbins-Domingo, Vice Dean for Population Health and Health Equity in the UCSF School of Medicine, and Dr. Bob Wachter, the Chair of the Department of Medicine at UCSF, to discuss viewers' vaccine questions. Jan. 14, 2021.

Got questions about the Covid-19 vaccine? Well, so do we.  Lucky for us, some of the country’s brightest and most-sought-out minds of the pandemic are based right here in San Francisco and answering your questions. 

Exploratorium listeners and cell biologist Jennifer Frazier took questions from participants for  UCSF doctors Bob Wachter and Kirsten Bibbins-Domingo during a virtual installment of the Exploratorium’s adult science series “After Dark Online” on Jan. 14., and we tuned in, too. Here’s a selection from the Q&A, which is edited for brevity and clarity. Watch the full video here

Frazier: How do we know the vaccine is safe, given the timeline of the development?

Wachter: As people probably heard, the world record for a vaccine prior to these vaccines was development of somewhere five, six, seven years. So it does seem amazing, but the shortcuts were all in sort of the side of where the money is. The normal thing that would happen would be six months of discussions within the company about the next step. And that took a day. This time, [one of] the shortcuts were people were working 24/7, they normally don’t do that. 

And so there were no shortcuts taken in the parts that matter: In the case of both vaccines and the rigor of the research to demonstrate that the vaccines are remarkably effective and are quite safe.

Bibbins-Domingo: And especially these first two vaccines, they build on technology and on scientific discovery that have been years in the making.

Frazier: Side effects. How do we weigh those against health, as some of the other considerations of the health of ourselves, our family, in our community?


[When I got it, the side effect was that it] felt like somebody slapped me in the arm. But we know a fair number of people, sort of in the 20 to 30 percent range, will feel pretty bad the next day. Fever, achy, tired, sleepy, and it goes away after a couple of days. The risk of those side effects goes up if you’re younger. The fact that I didn’t have bad side effects is probably a manifestation of how old I am, and largely because my immune system is not as good.

We’re talking about something that’s killing four thousand people a day. So even if there is like a one in a million side effect we haven’t found yet, it’s not a close call as to the chances of you’re going to get sick and die from that versus those chances you’re going to get sick and die from [Covid-19]. 

Frazier: We’ve seen that the greatest concern about getting vaccinated has been among black and Latino communities, often those that have been the hardest hit by the pandemic. Dr. Bibbins-Domingo, Given your expertise in population health and health equity, how do we make sure that we’re really listening to and acknowledging those concerns and addressing those concerns? 


The inequities in terms of the most severe outcomes, cases and deaths and during this pandemic have really have really been in our Black, Latino, indigenous communities and have been in communities who are poorer. And, oftentimes, these same communities have very legitimate concerns about trusting government, trusting the medical establishment, trusting science, because of historical instances where, really, there is basis for that mistrust.

I think everyone in the end will be motivated by something slightly different. And I think, for those of us who are physicians, I think being able to talk with patients and understand what is it, for you, that you’ve been concerned about during the pandemic? How can we understand and meet people where they are, and use the concerns to motivate? I actually don’t mind when people say they are hesitant; [they’re] just being cautious. I think the numbers suggest the number of people who really are opposed to getting the vaccine is actually very small.

Frazier: If you want the vaccine, what do you do? You know, if you’re 65 [year old], you’ve heard the governor say you’re eligible. And I think there’s, even right now, a tremendous amount of confusion of, do I register with my county, do I call my doctor or do I drive to the Disneyland super-site? 

Wachter: You’re going to see a huge push on the part of the state and the Bay Area to begin to open mass vaccination centers. At UCSF, we are almost done vaccinating our healthcare workers, and once we are through, we will begin informing our patients who are over first 75 and then 65 that they are eligible for vaccination. So please, you don’t need to call for that. You’ll get an email informing you when it’s your turn. I think the other large health care systems are going to do that, and I think you’re going to see [that at] CVS, Walgreens. It’s been chaotic. It’s confusing. But I think within two or three weeks, you’re going to start feeling very different.

Frazier: What’s the difference between the Pfizer and Moderna vaccine?

Wachter:The answer is, they are essentially the same. They use a slightly different vehicle of fat globules to surround the vaccine. The effectiveness is precisely the same: They’re both 94 to 95 percent effective in preventing infection. At UCSF, we’re giving people both, but I would get whichever one you can get first.

There are two other vaccines that are in the queue [that] may very well get approved in the next few weeks. They use different technologies, they may have different efficacy. We’ll have to see, but it’s going to be important to watch that, because you may, later on, be able to make a choice between vaccines. 

Frazier: How long is immunity good for? 

Bibbins Domingo: We just don’t know. We’re going to be following people to see how long that immunity lasts. But the way in which the immune system operates, the ways in which the mechanics of the vaccine appear to stimulate the immune system, suggests that it will be a longer term immunity. 

The big question with the one you’re asking: what was studied in the trials was the vaccine’s ability to protect against severe covid. It was not well studied whether it prevents infection or transmission of that infection. All indications are, and most virologists believe, that’s also the case. But those are things that are still being studied. It is one of the reasons why people will still be asked to mask after they get their vaccine.

Frazier: Are the current vaccines effective against the new variant? 

Wachter: Viruses mutate all the time. We now have seen at least a couple of variants that do appear to have significant differences in structure that do make a difference in their activity. The one in the UK, its main super-power is that it appears to be more infectious than the original Covid-19 virus that we’ve come to know and hate — and probably about 50 percent more. All evidence is that the vaccine will work equally well against it.

Were the vaccines tested on a variety of races?

Bibbins-Domingo: I believe the numbers in the Moderna trial are 38 percent nonwhite populations. And so that’s a really important and striking finding. The numbers for the Pfizer vaccine are lower, but still, I think it’s about 20 or 25 percent.

Wachter: It’s easy to get despondent, but I’d say this trial done 20 or 30 years ago, probably no one no one would have thought carefully about the importance of the diversity of the patient population. It’s really magnificent. 

Frazier: Are the vaccines safe for people who are pregnant, nursing, or people under the age of 16? 

Bibbins-Domingo: The way vaccines have been developed in this country is that they’re studied in adults. And then we figure out how to do studies in children. I will say they will be necessary, even though we know that there is a sort of a clear age effect in the likelihood of severe disease with children being spared, it seems, from the severe disease. 

These vaccines were not studied in pregnant and nursing women. But it’s quite clear that the recommendations from the [obstetrics] societies have been for pregnant and nursing women to get them. This is not like other vaccines, where the live virus particles have just been tamped down, which we’ve always been concerned about [posing] a risk in pregnant women.

Frazier: Are the vaccines safe for people who are immunocompromised?

Wachter: The answer, we believe, is yes. And again, because the vaccines right now do not use viral vectors, you’re not injecting someone with a virus.

Frazier: How important is the timing of the second dose? How much do we know about the efficacy of smaller or larger doses? 

Bibbins-Domingo: I think I think an important thing [is], even though there is more immunity before you get to the second dose, we don’t know the durability of the immune response without the two doses. I think an important piece here is that we probably, from a logistical standpoint, need to get more doses out there and be a little bit flexible on the timing. But I think what people should hear is that you should get two doses, at this point.

Wachter: We don’t know how long the first shot will last. Maybe immunity will begin to wane in month two or so. They’re not saying you should delay the second shots, but I think what they are implying is if your second shot is a week or two late because we don’t have the dose on hand just yet, there’s nobody who thinks that that kind of delay is going to cause any major harm. It’s important to talk, given that we’re in an emergency.

Frazier: When will we have 70 percent [of the population reach] immunity, if logistics are perfect? What are constraints?

Wachter: We all thought that the constraint would be the supply, and it’s a little bit shocking right now that the country has injected 30 percent of the existing supplies, [which means] 70 percent of vaccines are sitting in refrigerators and freezers right now. I think we will catch up with that probably in a few weeks.

If you think about 330 million people in the country, and if they can vaccinate 100 million people in 100 days in three, four months. You add to that the fact that probably 15 or 20 percent of the people have already been infected, but they’re going to be immune for the purposes of herd immunity in the short term [however, there’s a strong recommendation for them to get vaccinated still]. It wouldn’t be impossible, if everybody who’s eligible for a vaccine says, “I’m ready to get one,” [then] it’s probably the end of summer when you get to that number.

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REPORTER. Annika Hom is our inequality reporter through our partnership with Report for America. Annika was born and raised in the Bay Area. She previously interned at SF Weekly and the Boston Globe where she focused on local news and immigration. She is a proud Chinese and Filipina American. She has a twin brother that (contrary to soap opera tropes) is not evil.

Follow her on Twitter at @AnnikaHom.

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