Public Health

Candida auris, Marburg virus and latest FDA COVID booster authorizations with Andrea Garcia, JD, MPH


AMA Update covers a range of health care topics affecting the lives of physicians, residents, medical students and patients. From private practice and health system leaders to scientists and public health officials, hear from the experts in medicine on COVID-19, medical education, advocacy issues, burnout, vaccines and more.

AMA Vice President of Science, Medicine and Public Health Andrea Garcia, JD, MPH, covers the latest news physicians need to know, including: tracking the Marburg virus disease (MVD) outbreak, Candida auris symptoms, how sleep can impact vaccine effectiveness, and the FDA's latest authorization that children six months through four years old (who completed Pfizer’s original monovalent three-dose primary series more than two months ago) are now eligible to receive a single booster dose of Pfizer-BioNTech's updated bivalent shot. AMA Chief Experience Officer Todd Unger hosts.


  • Andrea Garcia, JD, MPH, vice president, science, medicine & public health, American Medical Association

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Unger: Hello, and welcome to the AMA Update video and podcast. Today, we have our weekly look at the headlines with the AMA'S Vice President of Science, Medicine, and Public Health, Andrea Garcia in Chicago. I'm Todd Unger, AMA'S chief experience officer, also in Chicago. Welcome back, Andrea.

Garcia: Hey, Todd. Thanks for having me.

Unger: Well, let's start off with some vaccine news. The Pfizer bivalent booster has now been authorized for certain children. Let's talk about that.

Garcia: Yeah, so recently we saw the FDA authorize Pfizer's bivalent COVID-19 booster, and that's for kids under five years old who were previously vaccinated with three doses of the original vaccine. Children six months to four years old who completed that original, monovalent, three-dose primary series more than two months ago can now receive a single booster dose of that updated bivalent booster.

We know that, since December, children in that age group who completed two doses of that original vaccine were eligible to receive the bivalent booster as their third shot or that last dose in their primary series. So, this new authorization is for young children who completed their three doses before the new, updated, bivalent booster was available.

Unger: So, is that what's driving the authorization or something else?

Garcia: So, yeah, FDA said that the decision was based in part on clinical trial data. They looked at data on 60 children in that age group who previously received three doses of the original vaccine and were given one dose of the company's updated booster. And one month after the children received that booster, they demonstrated an immune response to both that original COVID strain and to the Omicron BA.4 and BA.5 variants.

Dr. (Peter) Marks, the director of the FDA'S Center for Biologics Evaluation and Research, said in that FDA statement that the authorization provides parents and caregivers for children six months to four years of age who received that primary, three-dose series of the monovalent vaccine an opportunity to really update their children's protection. We know that vaccines offer the best protection against severe outcomes, and it is important to stay up to date, including with the bivalent vaccine.

Unger: Andrea, I'm glad to ask you this next question. Something that's been on my mind, I know, is about another round of booster shots for certain adults. Where does that discussion stand?

Garcia: Yeah, there was a recent report by The Wall Street Journal that said that FDA is deciding on whether or not to authorize a second round of that bivalent booster vaccine specifically for the elderly and other people at high risk of severe outcomes from COVID. And that final decision could come within a few weeks.

We know some people who are at high risk of severe outcomes have already been asking their doctor for a second round of that booster, even though we know that FDA and CDC have not signed off yet. We're also hearing some infectious disease experts call on federal health officials to really permit another round of boosting to better safeguard these people. And we've seen the UK and Canada move forward and to allow that.

Unger: Yeah, I've read about that, and I'm curious if there's data to support more booster shots. It's been a while since they were originally available.

Garcia: Well, we know the bivalent shots offer more protection. People who got that updated, bivalent vaccine are 14 times less likely to die than unvaccinated people and three times less likely to die than vaccinated people who received only that original vaccine. And that's based on data from the CDC.

But there isn't a lot of data on how long that protection from those bivalent boosters last. We know that studies of the original booster showed that protection against infection waned over time but protection against severe disease lasted longer. I think, given that, it's assumed that the immune defenses of the elderly, others with weakened immune system who got that booster late last year or some about six months ago now would benefit from another booster.

Unger: Well, we'll definitely keep our eye on that and look forward to more updates because we know that staying up to date with vaccinations is so important. And, on that topic, there's a new study that shows how one surprising factor can influence vaccine effectiveness. Andrea, what's that surprise?

Garcia: Well, that factor is sleep. And we know sleep is important for optimal health, and this new study is looking at the link between sleep and vaccine effectiveness. And that study was published recently in the journal of Current Biology. It did a meta-analysis on existing research on sleep and immune function after vaccination, particularly against influenza A and hep A and B.  And it found that sleeping less than six hours the night before getting a vaccination can limit your body's response to the vaccine, reducing protection. And, interestingly, that impact of poor sleep on immune response to a vaccine was highly significant in men and smaller and not significant in women.

Unger: That's so interesting. Why the difference?

Garcia: Well, there was a neurology professor who was quoted in a recent article who said there are known sex differences in immune response to foreign antigens like viruses, and, in general, women have stronger immune responses, including to the flu vaccine. However, these differences can become less pronounced over time with hormonal and other changes.

The study's coauthor, Dr. Michael Irwin, said that regardless of your gender, if you're sleep-deprived, jet-lagged, worked a night shift, or have swings in your sleep/wake cycle, you may want to consider delaying your vaccination. I do think we need some larger-scale studies to better understand these implications going forward.

Unger: I guess it obviously, then, is still early, but do you think this would be true of COVID vaccines, as well?

Garcia: So, the study didn't include an analysis of antibody response to COVID vaccines, but the study authors do believe that those same results would apply. That team did perform a further analysis, which showed that if a person arrived for a COVID vaccine without adequate sleep, their antibody response to that vaccine would be weakened by about two months based entirely on their body's initial response.

And most adults need seven to eight hours of uninterrupted sleep to achieve that restorative sleep, and that's based on what we know from CDC. But sleeping six or fewer hours a night, which many people do, can create a number of health problems, in addition to that reduced immune response.

Unger: The subject of sleep just seems to be in the zeitgeist right now—so much talk about it. I think we're going to have an update dedicated to that in the future, looking at my crystal ball right now. Andrea, let's move to a new topic. Last week was the first time that we talked about this deadly fungus that has been spreading quickly in the U.S. Any updates on that?

Garcia: Not really a lot new, but I would just refresh people's memory that last week CDC said that deadly fungal infection known as Candida auris or C. auris is spreading at an alarming rate in health care and long-term care facilities across the U.S. I think that's important to keep in mind—that this isn't in the community. It's really in health care settings.

C. auris is more likely to affect patients who have weakened immune system, who receive a lot of antibiotics, or have devices like tubes going into their body—so think breathing tubes, feeding tubes, catheters. Something we didn't talk about last time was symptoms, and the most common symptoms are fever and chills that don't improve after antibiotic treatment. And those symptoms of C. auris can depend on the part of the body affected because it can cause different types of infections—so bloodstream infection, wound infection, or even ear infection.

Unger: Is there any way to prevent it?

Garcia: So according to CDC recommendations, several infection control measures can help prevent C. auris, including hand washing and thoroughly cleaning and disinfecting hospital environments, equipment that is shared among patients—so think blood pressure cuffs, temperature probes, ultrasound machines should be thoroughly disinfected. We know that alcohol-based hand sanitizer is the preferred hand hygiene method for C. auris when your hands are not visibly soiled.

And PPE, including gowns and gloves, should be used to reduce the spread of infection in health care facilities. It's key here to ensure that all health care personnel adhere to those infection control recommendation. That's really critical to preventing transmission.

Unger: Well, that's good to know. Believe it or not, we've got another outbreak to worry about. I know you're getting lots of questions on this particular topic. Tell us more.

Garcia: So, there's an ongoing Marburg fever outbreak in Equatorial Guinea, and that's been something we've been watching. And according to a recent STAT News article, it's significantly larger than had been previously acknowledged. This is according to new information that was released this week by the WHO. They warned that there may be undetected chains of transmission.

That article showed that the latest update shows the number of confirmed and probable cases has grown from 9 to 29. Some of those have links to known cases. Others do not. And that's where we're seeing that suggestion that there's the potential for undetected community spread. And I think that's not all. We know that, on Tuesday, Tanzanian authorities announced that they, too, had detected their country's first Marburg outbreak. To date, there have been at least eight cases there, five of them fatal.

Unger: Andrea, Marburg virus is not something we hear a lot about. I do know one thing. It's serious, and you don't want to get it. For those of us out there that want to know a little bit more, can you give us some background on it?

Garcia: Yeah, so it's a close relative to the Ebola virus. It spreads through direct contact with broken skin, blood, and other bodily secretions from an infected person. It can also spread through handling of materials, such as bedding that's contaminated with bodily fluids.

We don't have any approved vaccine or antiviral treatments for Marburg virus. Patients are generally treated with supportive care, primarily oral or intravenous fluids to replace those lost through vomiting and diarrhea. And containment efforts are being put in place to help prevent international spread. I think we're hearing from WHO that the risk here in the U.S. right now for this is low, but it is something we're keeping an eye on.

Unger: All right, Andrea, thank you so much, and please keep us updated as news develops there. That's it for today's update. We'll be back with another episode next week. In the meantime, you can see all our videos and podcasts at Thanks for joining us today, and please take care.

Disclaimer: The viewpoints expressed in this video are those of the participants and/or do not necessarily reflect the views and policies of the AMA.