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The Dose


COVID Vaccines Save Lives, But We’re Chasing a Moving Target

Illustration of Dose Episode 74

Illustration by Rose Wong

Illustration by Rose Wong

  • On the latest episode of #TheDosePodcast, @Alison_Galvani and @EricSchneiderMD use data to show COVID-19 vaccines have saved 200,000 lives, avoided a million hospitalizations, and are the most effective way out of the pandemic

  • Even as winter approaches and COVID-19 surges again in Europe, American vaccination rates have plateaued. Learn more about policy solutions to increase uptake and ultimately end the pandemic on #TheDosePodcast.

Vaccines have saved thousands of lives and are an incredible tool in the seemingly endless battle against the coronavirus. But even with COVID surging anew in Europe as winter approaches, the rate at which Americans are getting vaccinated has plateaued.

On the latest episode of The Dose, Alison Galvani, founding director of the Yale Center for Infectious Disease Modeling and Analysis, and Eric Schneider, M.D., senior vice president for policy and research at the Commonwealth Fund, bring listeners up to speed on the state of the pandemic.

Galvani and Schneider have been using data to show how effective the vaccines are at preventing deaths and hospitalizations — and how, in the absence of successful vaccination campaigns, we are still losing people to the virus. Increasing vaccine uptake through mandates and administering boosters will help curb this pandemic. But to stave off future threats, it’s vital that we also strengthen the public health system and make it easier for all Americans to access health care, they say.


SHANOOR SEERVAI: The coronavirus continues to be a moving target, evading scientists and health care professionals alike. The thought of entering a second pandemic holiday season is daunting, but this winter, unlike the last, we have a very powerful tool to fight the virus — vaccines. I’m Shanoor Seervai, and on today’s episode of The Dose, we’re going to talk about how vaccines have changed the course of the pandemic.

My guests are Alison Galvani, the founding director of the Yale Center for Infectious Disease Modeling and Analysis, and Eric Schneider, senior vice president for policy and research at the Commonwealth Fund. Alison and Eric have been using data to show how vaccines are saving lives and where, in the absence of successful vaccination campaigns, we are still losing people to the virus.

Alison, Eric, welcome to the show.


ERIC SCHNEIDER: Great to be with you, Shanoor.

SHANOOR SEERVAI: So, it’s November. The holidays and the winter are around the corner. As this pandemic drags on, I want to ask the question that I imagine everyone in the world would love to know the answer to: Are we near the end?

ALISON GALVANI: Well, unfortunately, I don’t think we’re near the end. The virus has demonstrated itself to be able to evolve rapidly, and more transmissible variants that, to some extent partially evade preexisting immunity, is a real concern.

ERIC SCHNEIDER: Yeah. I would just add that, that it appears that COVID will become endemic is becoming endemic in the U.S. for sure. Even though COVID is not influenza, the pattern could very much be like influenza, getting booster shots each year.

SHANOOR SEERVAI: Okay. So if this isn’t the end, then how do we characterize this moment? Eric, you and I have sort of talked about this as a race.

ERIC SCHNEIDER: I think we’re certainly further along in the race than we were. But with millions of people still unvaccinated, the risks of hospitalization, serious illness, death are still pretty high for a large segment of the American population and of the world’s population.

SHANOOR SEERVAI: Okay. So then let’s move on to your research. What are you focusing on right now and what are the most pressing questions?

ERIC SCHNEIDER: I’ll start from the Commonwealth Fund perspective. We have been interested in the challenge of getting vaccines to the entire population and particularly to those who are most at risk. We knew from prior experience with influenza vaccine and other voluntary vaccines that the U.S. doesn’t have a very robust system for distributing vaccine. We’ve certainly achieved higher levels of vaccination against COVID than for some other vaccines — we’re now at as much as 60 percent of the population vaccinated; among high-risk individuals as high as 80. The challenge is to get to everyone who could benefit from the vaccine.

SHANOOR SEERVAI: Alison, what are you working on?

ALISON GALVANI: So currently, in collaboration with Eric, we’re focused on comparing the costs of vaccination versus the medical costs and productivity losses that have been averted by vaccination.

SHANOOR SEERVAI: That’s interesting. Tell me what you’re finding.

ALISON GALVANI: Well, so it can be hard to appreciate the effectiveness of public health measures because successful measures lead to the absence of bad outcomes. So with modeling counterfactual scenarios, we are able to evaluate how much worse the pandemic would have been if it had not been for the vaccination campaign. So we found in our work with Eric that the vaccination campaign that was implemented has already saved well over 200,000 lives and averted more than a million hospitalizations. It also blunted the repercussions of the more transmissible variants that have emerged, such as the Delta variant.

SHANOOR SEERVAI: I mean, I want to take a minute to just talk about how incredible that is. Two hundred thousand lives saved. A million hospitalizations averted. Did we ever dream that the mRNA vaccines would be as effective as they are?

ALISON GALVANI: I think we may have dreamt it. But I would have been happy with a much lower efficacy vaccine, and was just delighted to see above 90 percent efficacy for averting deaths and hospitalizations against the original COVID variant.

SHANOOR SEERVAI: And then you did mention Delta briefly so let’s come back to that because Delta complicated things. Alison, can you tell me about how Delta complicated the work that you’re doing, the models that you’re looking at?

ALISON GALVANI: Sure, so with the emergence of more transmissible variants, we are chasing a moving target. So as transmissibility increases, the level of herd immunity needed to stem transmission simultaneously increases. Such a shifting landscape makes vaccination all the more important. Conversely, the lower the vaccination coverage, the higher the probability that novel variants will emerge because each infected individual gives the opportunity for the virus to mutate and evolve.

SHANOOR SEERVAI: Explain that to me in a little more detail. What does that mean for public health and for our safety?

ALISON GALVANI: Every time a person is infected and the virus is replicating, there’s probability of mutation. Of course, there’s some mutations that don’t lead to higher transmissibility, but when a virus mutates into a more transmissible form, just through the process of natural selection, it’s likely to sweep through the population more rapidly and displace the previous strains.

SHANOOR SEERVAI: So basically, what you’re saying is that the more unvaccinated people there are, the more likely it is that we are creating welcoming hosts for the virus to mutate.


SHANOOR SEERVAI: So let’s talk about what the most urgent problems we have to grapple with now are. Eric, can you talk about the challenges that we’re seeing, you know, even as vaccinated people have breakthrough infections?

ERIC SCHNEIDER: Yeah, sure. And I think this is why it’s so important that primary vaccination reaches as many people as possible, because unvaccinated people are more likely to transmit the virus and the variants. And we know now that immunity from the vaccines wanes, that there are breakthrough infections, and that after six months people can become infected even if they’ve been vaccinated. So the more virus is out in the community circulating, the more likely it is that even people with prior vaccination will also get infected. I saw an estimate recently that as many as a third of people in the hospital are people who’ve been vaccinated previously. So the immune systems may not have responded or they had waning immunity. It’s still much lower frequency, it’s much less risky if you’re vaccinated, but that will be a problem going forward. And that’s the reason for the booster campaigns.

SHANOOR SEERVAI: Are you looking at the boosters in the modeling work that you’re doing and how the booster campaign is impacting the course of the pandemic?

ALISON GALVANI: We haven’t yet, but with the implementation of different vaccination strategies, such as the interjection of boosters and vaccination of children, we will be looking to incorporate those aspects.

SHANOOR SEERVAI: Can you predict what you’ll see when you incorporate these aspects?

ALISON GALVANI: Well, boosters reduce the mortality and hospitalizations. But if we had a choice between fully vaccinating someone that currently is unvaccinated versus a booster for someone that’s already had two doses, it’s going to be more effective to vaccinate the unvaccinated person. That doesn’t mean that it’s not highly cost-effective to give boosters to mitigate severe outcomes.

SHANOOR SEERVAI: I want to focus on what you just said, Alison, because we are in a global pandemic and we’re seeing that, you know, in the poorest countries in the world vaccination rates are still very low, some even in the single digits. And you just said that it is more effective to vaccinate an unvaccinated person than to give a vaccinated person a booster. How are we going to end a global pandemic if we don’t address low vaccination rates in other countries?

ALISON GALVANI: Well globally, we do need to address low vaccination in other countries, and there are a number of tools. There are actually new vaccines on the horizon that are low cost, and don’t require cold chain. So one challenge with Pfizer in particular, but both Pfizer and Moderna, they require stringent cold chain, which is challenging to maintain in countries that have low resources.

SHANOOR SEERVAI: Eric, what are your thoughts about getting higher rates of vaccination globally?

ERIC SCHNEIDER: It’s clearly a necessity to get the rates up globally. The supply is abundant. It’s sort of a tragedy actually that the U.S. has abundant supply — we have enough vaccine to vaccinate every American, yet we have pockets of unvaccinated people. We’re actually just getting underway on vaccinating children, who are an important reservoir for transmission. I think the more that wealthy countries can do to make sure that manufacturing capacity and distribution happens around the world, the less likely it is that new variants will boomerang back and cause the sorts of problems that we’ve seen over the last year and a half.

SHANOOR SEERVAI: Let’s talk a little bit about these unvaccinated pockets, because you’ve looked at states where vaccine uptake is lagging, like Florida and Texas, and you’re able to show how many lives we’ve lost in these states for that reason. So tell me what you’re finding and what we can do about.

ALISON GALVANI: Sure. So by August a number of states, including Vermont, Massachusetts, and Connecticut surpassed over 70 percent coverage of their adult populations, while coverage in other states, such as Florida and Texas, were below 60 percent. We found that if the vaccination pace in Texas had matched that achieved in the Northeast, over 30,000 hospitalizations and more than 6,000 deaths could have been averted. Similarly, in Florida, comparing the vaccination program that they rolled out and the coverage they achieved with what could have been achieved, they could have reduced hospitalizations by over 60,000 and deaths by more than 16,000.

ERIC SCHNEIDER: That analysis was consistent with some other work on vaccine deserts with Ariadne Labs, creating a vaccine equity planner that enables state officials to look at where vaccine is not readily available to populations where low vaccination rates exist. So that’s part of an effort to try to get vaccination increased in many of them rural areas now, where vaccine rates are low.

SHANOOR SEERVAI: Are there other characteristics of places where vaccine rates are low? You mentioned rural areas.

ALISON GALVANI: Well, I never imagined that public health measures would become politically polarized, but the propagation of vaccine hesitancy by some conservative leaders and conservative media costs lives. So we do see discrepancies based on political affiliations in different regions.

SHANOOR SEERVAI: I did also want to ask Alison, you’ve talked about how your modeling work focuses on deaths and hospitalizations. What about cases? Why aren’t you focusing on that as much?

ALISON GALVANI: Oh, so we absolutely are incorporating cases. In fact, that’s fundamental to the transmission model, and the first layer are infections, to keep track of infections. I just didn’t specifically mention infections because of paramount concern are the deaths and hospitalizations. But cases are important. They’re key to transmission. Even asymptomatic cases can lead to transmission and, in fact, we showed in previous work that the majority of transmission occurs from people in the presymptomatic phase and who are asymptomatic. So silent transmission from people who aren’t exhibiting any symptoms.

SHANOOR SEERVAI: Right, but how do we solve a problem like that? I mean, it sounds impossible to me.

ALISON GALVANI: It does make control of COVID more challenging than a lot of diseases because symptom-based mitigation such as temperature checks would miss everyone in the presymptomatic phase and those asymptomatic infections. So this is again why we come back to why vaccination is so critical, because it averts the cases to begin with. And then also nonpharmaceutical measures such as mask-wearing are key as a complement because even if someone feels well, they could still be shedding the virus.

ERIC SCHNEIDER: I’ll just say also along with masks, testing, rapid testing is the other strategy that can be really useful in this context, if people are infected and don’t know it.

SHANOOR SEERVAI: I wanted to ask, since we have been talking about silent transmission, how the pandemic has changed the modeling work you do more broadly for epidemiology. Is this pandemic reshaping the science around modeling?

ALISON GALVANI: Well, we’re using the same modeling approaches that we have in the past, but for every disease we need to take into account its unique clinical features. We know that COVID is unusually transmissible in the presymptomatic phase. So that’s a key component to incorporate. And our models also take into account asymptomatic transmission. COVID is quite unusual in having such high transmissibility during the presymptomatic phase. In most diseases, people don’t become really infectious until after the onset of symptoms, which makes the control of other diseases more straightforward based on symptoms.

SHANOOR SEERVAI: Eric, would you mind — since we work together, I know this — would you mind talking about your own experience gathering with people where everyone’s fully vaccinated?

ERIC SCHNEIDER: Sure, and I think it’s a cautionary tale. I was at a dinner with a couple dozen other people. People had their masks off because we were eating, and it turned out that there was a person at the dinner who had an asymptomatic infection. And because we were doing rapid antigen testing we became aware that that was the case within about 12 hours.

The good part was that everyone was able to take precautions right away to prevent further transmission. The unlucky part was that I got a breakthrough infection. I was about six months after my vaccine. I had to go into isolation, had symptoms. So I actually lost my sense of taste and smell. It is a very strange virus, unlike others I’ve experienced. I was very fatigued, had some low-grade fever, and had to isolate for 10 days. Fortunately, mostly recovered, a month or so later. And fortunately, I was able to take precautions and not transmit the virus to other people around me.

SHANOOR SEERVAI: It’s very scary. And particularly, you know, I look back to how many times over the past 18 months I’ve asked you for advice, and even taking all the precautions you did, you still found yourself in a situation in which you got a breakthrough infection.

ERIC SCHNEIDER: Yeah, I just saw a good study on this recently that what’s called the secondary attack rate, the likelihood that a person will infect other people around them, even when everyone’s vaccinated, seems to be about one out of four will have a breakthrough infection. So it’s something we’re going to see. As we have really opened up, people are out in restaurants, dining, traveling. It’s likely over this wintertime that we’re going to see a surge, nothing like what we saw probably a year ago, but I don’t think the virus is done with us yet.

SHANOOR SEERVAI: So let’s shift now to where policy comes in. What can policymakers do to get more people to take the vaccine?

ERIC SCHNEIDER: I’ll start just by saying that one step we probably could have taken more aggressively early on was to engage the primary care community more directly in vaccination because clinicians are among the most trusted messengers. We’re taking lessons learned from the first phase of vaccination of adults. And I think those are being applied now to the pediatric population. And then many places are moving to mandates, and the Biden administration issued a regulation through the Occupational Safety and Health Administration, OSHA, requiring vaccination for people who are employed by companies with more than a hundred employees. That’s been challenged in court, as one would predict it would be, but the OSHA mandate for worker safety has stood the test of time in prior court challenges. So it does appear that mandates are very effective.

ALISON GALVANI: Yeah, I agree. Given the plateauing vaccination rates, mandates are necessary to curtail the pandemic. Some people may not like mandates, but they are effective and necessary to save lives. I think we’ve become numb to the death toll, still over a thousand a day. I mean, that’s more deaths each and every day than Australia has had over the entire pandemic. Just because we’re done with COVID doesn’t mean that it’s done with us.

SHANOOR SEERVAI: Alison, do you have any sense of the impact of long COVID on vaccinated people?

ALISON GALVANI: Well, I do expect that the vaccine is averting long COVID in that we know it averts cases, although you can have a mild infection and still suffer from long COVID. Expect that more severe infections are more likely to lead to long COVID. So by vaccinating and preventing severe symptoms, we’re probably going to also be reducing long COVID in the people even who get infected.

SHANOOR SEERVAI: And Alison, are you concerned that there may be more virulent strains of the virus yet to come?

ALISON GALVANI: Absolutely. I mean, we’ve seen the emergence of one strain after another that’s more transmissible and in some cases had higher case fatality. So I’m very concerned about that.

SHANOOR SEERVAI: And then, of course, we’re going to see other pandemics in the future. Are we prepared for the next pandemic and have we learned anything that will protect us from that?

ALISON GALVANI: I think we’ve learned that there’s a very short window of opportunity to control a pandemic. And, unfortunately, the U.S. was slow to act to implement testing, to even have personal protective equipment for health care workers. That should be straightforward, to maintain the stockpile of personal protective equipment. And, you know, listening to the scientists. Unfortunately, we had some political leaders that disregarded the science.

ERIC SCHNEIDER: I think the other vulnerability that the pandemic revealed is that we’ve underinvested in public health for years, but we really need a significant investment in modernizing and upgrading our public health systems. We really have no effective surveillance system for early detection of COVID virus entering the country and being able to have that sort of rapid response. But also have the public health officials in place with the data they need to generate estimates of community transmission, forecasts of community transmission in local areas. We just are living in a world of where it’s really a necessity now to have this sort of capabilities, to monitor data and create a situational awareness of where new pandemic threats may be emerging and how they’re entering the population.

SHANOOR SEERVAI: So do you think that next time we will have this surveillance in place?

ERIC SCHNEIDER: We certainly will be in a better position to create those systems. The jury’s still out. There’s a large amount of federal money now invested in what’s called public health data modernization. But we don’t have the ease of exchange of data between our health care providers, pharmacies, public health officials, to be able to get real-time data on what’s happening. We sort of cobbled together some systems to allow us to report on cases and hospitalizations.

SHANOOR SEERVAI: Alison, do you have any final thoughts?

ALISON GALVANI: I think when people are hesitant to seek health care and to be diagnosed due to financial barriers, it’s all the more challenging to pick up on emerging and spreading infections. The federal government is covering COVID testing and vaccination. The pandemic has underscored the weaknesses of the American health care system, and hopefully next time everyone in the U.S. will have access to health care, have a primary care provider, and will not hesitate to seek medical care when they need it.

SHANOOR SEERVAI: Alison Galvani, Eric Schneider, thank you so much for joining me today.

ERIC SCHNEIDER: Thank you, Shanoor, it was a pleasure.

ALISON GALVANI: Thank you so much.

SHANOOR SEERVAI: This episode of The Dose was produced by Jody Becker, Karl T. Wright, Naomi Leibowitz, and Joshua Tallman. Special thanks to Barry Scholl for editing, Jen Wilson and Rose Wong for our art and design, and Paul Frame for web support. Our theme music is “Arizona Moon” by Blue Dot Sessions. Our website is There you’ll find show notes and other resources. That’s it for The Dose. I’m Shanoor Seervai. Thanks for listening.

Show Notes

Bio: Alison Galvani

Bio: Eric C. Schneider, M.D.

Publication Details



Shanoor Seervai, Former Researcher, Writer, and Lead Podcast Producer


Shanoor Seervai, “COVID Vaccines Save Lives, But We’re Chasing a Moving Target,” Nov. 19, 2021, in The Dose, produced by Jody Becker, Karl T. Wright, Naomi Leibowitz, and Joshua Tallman, podcast, MP3 audio, 24:07.