COVID-19 Resource Center

COVID-19 Resource Center


Healio Interview.

Disclosures: Creech reports being a phase 3 principal investigator for Moderna and Johnson and Johnson COVID-19 vaccine studies, the funds for which were paid by the NIH, which sponsored the trials.
January 25, 2021
6 min read

Q&A: The challenges affecting the COVID-19 vaccine rollout


Healio Interview.

Disclosures: Creech reports being a phase 3 principal investigator for Moderna and Johnson and Johnson COVID-19 vaccine studies, the funds for which were paid by the NIH, which sponsored the trials.
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As of Jan. 24, the United States had distributed more than 41.4 million doses of COIVD-19 vaccine, and more than 18.5 million people had received at least one dose, according to CDC data.

Put another way, the U.S. has administered 6.6 COVID-19 vaccine doses per 100 people in the country, according to data from Our World in Data, a research group affiliated with the University of Oxford. In comparison, the United Kingdom has administered 10.4 doses per 100 people and Israel has administered 44.2 doses per 100 people, the highest rate in the world.

Why is the U.S. behind the pace of other countries? We spoke with Infectious Diseases in Children Editorial Board Member C. Buddy Creech, MD, MPH, director of the Vanderbilt Vaccine Research Program, about the issue of vaccine distribution.

Question: What is the delay with distributing the COVID-19 vaccines?

Answer: It's interesting. If this were any other vaccine launch, we would be amazed at how many people we vaccinated so quickly. But certainly, we live in a time where every day matters with how quickly we can get this vaccine into the arms of folks in the U.S. So, it's a challenge.

We want to do it well, and we want to get it into those individuals who need it the most. And I think one of the challenges is that, as we've seen it roll out, some states have been a bit more organized and effective in how they've gotten vaccines rolled out than others.

This has been a challenge, and I think it's a challenge, in part, because — at least by my read of the situation — we don't necessarily know how many doses are coming on a regular basis. So therefore, it's really hard to plan for it. But the other aspect of this is that the initial plan was to give out just enough vaccine to then make sure that those people can get their second vaccine 3 to 4 weeks later.

I think many of us saw the difficulty with that plan. I would rather have 100 million people have one dose than have 50 million people have two doses. But we recognize that I think that created some confusion about how many doses people were getting, when they would get their resupply and whether or not those production numbers were going to match up. So, I think there's been a lot of confusion on how to implement this at the local level.

Q: In retrospect, do you think it was a right decision to open up the vaccination to more people?

A: Well, it's hard to know, because what we've really got to do is make sure that those who are older than 65, those who are living in nursing homes and long-term care facilities, those who are caring for individuals with COVID-19 and those who are at the highest risk of exposure and disease, that they are prioritized. Although that sounds easy enough to do, the real challenge is how do we actually operationalize that? Do we have a database of individuals who are older than 65 in our communities? How do we do that? Do we rely on physicians’ offices? Do we rely on public health departments? Do we invite SignUpGenius or some other electronic means by which we ask people to sign up on their own and confirm that they belong to that group? There are a lot of questions here, and I think we are struggling with how to do it, because quite frankly, this is the first time we've ever had to do it. This is the first time we've ever rolled out a vaccine during a pandemic, where we've had to strategically layer the groups that are eligible. We didn't have to do this back in 2009, when we had the H1N1 pandemic. We were able to really launch it for most people at one time. So, we're still learning the best ways to do this.

Q: Recently, the CDC has said that second doses can be delayed for up to 6 weeks after the first dose, instead of 21 days for the Pfizer-BioNTech vaccine and 28 days for the Moderna vaccine. Is there science to support this, and will it help with the supply?

A: Well, I think the science that supports it is our fundamental understanding of the immune system. Our immune systems are really smart. And for most vaccines, actually, the longer you wait between that first and second dose, the better the response. Now, the disadvantage of doing that during a pandemic is it prolongs the period of time where folks are not maximally protected.

So, we want to be careful about allowing a greater window there because of that increased period of vulnerability, but we also don't want it to be so rigorously enforced that it actually serves as a deterrent to get that first vaccine.

I do agree that it also gives our public health partners a little bit more flexibility as they start to make plans for vaccination because maybe it will allow them to open up more spots, because if they do get a disruption in the supply chain of vaccine 2 to 4 weeks later, it's not as if they're scrambling to try to find vaccine to give individuals during a very tight window. They now have a bit more margin to get second vaccines to the individuals when it comes along.

Again, I think we're doing this for the very first time in terms of the operations aspect of this, and I think as our CDC colleagues and FDA colleagues and certainly those in public health provide even more leadership on this, things will become a bit clearer. I think a lot of folks are looking to those states that have done it well, or that are doing it well to figure out best practices. One of the first things that has to happen is to make absolutely certain that we have a really good understanding of not only the current vaccine supply, but what the projections over the next 8 to 16 weeks will be. Without knowing that, it's really hard to plan for vaccinations of our citizens.

Q: Is there any way we can estimate when primary care physicians can expect a reliable supply of vaccine?

A: Well, I think that's going to be variable based on location, and I think a lot depends on what happens with the Johnson & Johnson vaccine and the AstraZeneca vaccine here in the U.S. I think, until we have more vaccines at the ready, and until we can get a little bit more time for Moderna and Pfizer to further increase their production, I think we're going to be living with a relatively scarce commodity. I say scarce, but we've already vaccinated 20 million individuals, so that's a good start. It's not where we would like it to be. We're on track right now based on the estimates I've seen that we're vaccinating about a million a day, which, again, for any other vaccine would be a really good number, but we've got a lot of work left to do.

Q: Do you think the U.S. has ordered enough doses?

A: Well, we would have to do the math, and I don't know what the current estimates are. But if we do the math, that there are well more than 300 million individuals in the country, of whom the majority will be eligible for the vaccine and be able to receive it safely, you can imagine that it doesn't take long for us to require half a billion doses of vaccine to get the majority of our population vaccinated.

There are some unanswered questions that will affect that vaccine a lot, such as, “Does everyone need two doses?” Maybe those who have had COVID-19 only require one dose, because they've already seen this virus, they've already developed an immune response, and so, maybe that's a method for extending our vaccine supply.

Regarding children, as we study them, maybe they're going to need a smaller dose than the doses that are used in adults. Again, if that's the case, then we can stretch our vaccine supply even further.

But I think realistically, we're going to be vaccinating individuals well through the summer and fall, and that will either include the current vaccine, or potentially introduce newer booster vaccines — as Moderna brought up — to cover some of these variants that we know will occur.


CDC. Interim clinical considerations for use of m RNA COVID-19 vaccines currently authorized in the United States. Accessed Jan. 25, 2021.

Our World in Data. Coronavirus (COVID-19) vaccinations. Accessed Jan. 25, 2021.