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"I have the best job in the world because I'm learning something new every day." So says Dr. John Brooks '76, a medical epidemiologist with the Centers for Disease Control in Atlanta. John's professional journey has taken him deep into many of the infectious disease outbreaks and public health crises of the past two decades. From HIV/AIDS to Ebola, from the health impacts of Hurricane Katrina to anthrax bioterrorism, John has led teams that played a pivotal role in research, response, and prevention. This year, he has helped lead the CDC's response to the COVID-19 pandemic – during which, he emphasizes, "we have been learning all along the way and will certainly continue to learn as we go forward."

John, would you share a little bit about your background? What made you decide to go into medicine and what was the path that brought you to your current role at the CDC?

After leaving Potomac (which ended in ninth grade in those days), I went on to Exeter, then Wesleyan College, then Harvard Medical School. I was a geology major, and in between college and medical school, I did a lot work in geochemistry. I thought about doing graduate work in that field, but I ultimately realized that medical school would be a better fit for me. I enjoy interacting with people, and soils and sand don't talk much!

I was almost 30 when I started med school, the second oldest in my class. I knew that I wanted to focus on infectious disease, and I had a particular interest in HIV/AIDS. I think one reason I'm so committed to the study of infectious diseases is that there's a strong social justice side to it – taking care of people who are often marginalized and don't have access to good health care. I also worked at a VA hospital for a while. Veterans deserve our care, and I found it rewarding to work with patients who have sacrificed so much.

I found my sweet spot, professionally, when I was accepted to the CDC's Epidemic Intelligence Service – essentially a two-year training program for infectious disease detectives. I quickly saw how fascinating epidemiology can be. After that, I spent two years in the CDC's Foodborne Outbreak Division, dealing with really interesting cases. These jobs focused on problem-solving and prevention – identifying holes in our collective armor that need to be addressed.

Ultimately I ended up in the CDC's Division of HIV/AIDS Prevention, where I still reside. But this job has positioned me to address many other infectious diseases. I've led CDC emergency-response teams focused on a wide range of public-health crises, from anthrax to SARS, H1N1 flu, Hurricane Katrina, Ebola, Zika, and now COVID-19.

When we consider the challenges posed by various viruses, including the current pandemic, it's useful to pause and consider how far we've come with HIV/AIDS. Once, not that long ago, AIDS was a death sentence. But now we have treatments – antiretrovirals – that allow infected individuals to live a normal, healthy life. You basically take one pill a day, with virtually no side effects. The future of HIV treatment looks brighter still; we anticipate moving away from daily oral medications toward injections that can be administered every couple of months, or even a dermal implant. And with HIV, we know that treatment prevents transmission. The ramifications of the progress we've made with this particular virus are tremendous and show what medical science is capable of.

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Talk about the CDC's roles in a pandemic. What are the various areas that your agency addresses, and which parts of that are you personally involved with?

The purpose of the CDC is to prevent illness. The agency, which is part of the U.S. Department of Health and Human Services, was started in Atlanta in 1946, with the primary goal of preventing malaria, which was occurring in southern states, from spreading in the U.S. In the following years, the CDC played a major role in eradicating smallpox, and its mission expanded to address all kinds of communicable illnesses. The agency coordinated America's response to various threats as they emerged – from some of the big flus of the 1960s to HIV/AIDS, toxic shock syndrome, and Legionnaire's disease.

Today, in addition to infectious diseases, we study and work to prevent many types of chronic illness – cancer, Alzheimer's – anything that affects large numbers of people and that medical science views as potentially preventable. In addition, the CDC responds to natural disasters that have associated health impacts. For example, I set up the system to monitor for infectious outbreaks in Louisiana in the wake of Hurricane Katrina. There were thousands of people crammed into makeshift shelters without great sanitation. So we were on hand to monitor for outbreaks of diarrhea, measles – things that can spread fast in conditions like that and become major health threats. Fortunately, those particular threats didn't materialize there.

The past year has been challenging for everyone. What are some of the key challenges that the CDC has faced, and continues to face, with the COVid-19 pandemic?

I think we were all surprised at the speed with which this event progressed, and the scope of it. How quickly it spread from China to all over the world, and how fast it spread here in our own country. It is astonishing to realize that this disease has resulted in more than 500,000 deaths in the U.S. in just over a year. This is especially disconcerting because we actually had the ability to stem the spread, if we had let science lead the way.

Under the last administration, the CDC's traditional role of leading the national response in an infectious disease emergency was impaired. The process became politicized, and we weren't able to do everything the way we normally would – including talking openly with the American people on a regular basis. That's critical. During previous emergency responses, we would hold regular – often daily – briefings for the press and the public about what was going on. What do we know; what do we not know; what can you do to protect yourself and your family? These are the kinds of issues we would typically address, sharing new information as it emerged. This time, because the response was being coordinated by a White House Task Force, the CDC had to clear all public statements, and even updates to our website, before making them.

Regular communication is vital in a public-health emergency. For one thing, it enables us to explain changes in guidance. Early on, we told people they didn't need to wear a mask; in fact, we actively discouraged that, saying that scarce personal protective equipment should be reserved for medical professionals and first responders. Everybody up to Dr. Fauci was saying this. At the time, we didn't have evidence that the infection could be spread by people who didn't have symptoms. So that was a surprise. When it became obvious that you could transmit this disease without being symptomatic, we determined that the best way to stem transmission was for everyone to wear a mask when around others; the mask provides protection for both the wearer and those with whom that person comes into contact. That was a really big reversal. Normally, we would have given press interviews explaining the rationale for this change, but we didn't have that opportunity. I think there was fear that saying certain things could have unintended consequences, sparking panic, maybe affecting the stock market or even the election.

This hurt the agency's credibility and impaired our national response to the pandemic. The result of failing to be transparent is that people become suspicious. They try to second guess. They speculate. They accuse medical professionals of "lying." Another very serious result has been decreased adherence to practices that could help us put an end to this pandemic – from social distancing to mask wearing to getting everyone vaccinated. If people don't understand or believe public health guidance, if they don't see public figures modeling the scientifically informed and recommended prevention strategy, they are less likely to follow it.

You fight fear with facts. Human beings are prone to being scared easily – fear triggers that fight or flight response that is important for our survival. The truth, though, is that there is a lot that we, as individuals, can control.

One thing that's clear is that everybody should be prepared for the "facts" to change. We are constantly learning. Being able to explain why things have changed and bring people along in their understanding and their behaviors is key to a successful public health effort.

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What can you tell us about the development of the COVID vaccines?

I am struck by the unprecedented pace with which we have arrived at not just one, but multiple, effective vaccines. This is a tribute to the commitment of the federal government to invest in this effort. Significant investments were made in the development of the products themselves, along with a guarantee from the government to buy a certain amount of the vaccines when available. So the producers had a guaranteed market for their products, providing a tangible incentive to move the development forward and make the vaccines available as quickly as possible. Those investments by the government will ultimately be worthwhile, both in preventing illness among Americans and also in leading to the more rapid restoration of a normal economy.

In addition, a real leap in technology over the past decade or so made it possible for the pharmaceutical companies to develop these vaccines quickly. That leap was the development of genetic vaccines using RNA, called mRNA vaccines. Traditional vaccines put a piece of a weakened or inactivated virus or bacteria into our bodies to trigger an immune response. By contrast, mRNA vaccines teach our cells how to make a protein – or even just a piece of a protein – that triggers the desired response, producing antibodies that afford protection from infection when the virus enters our bodies. This technology is more efficient than traditional vaccine development; it can be standardized and scaled up quickly. That's what we've seen with the COVID vaccines.

mRNA technology isn't entirely new. It was used to develop a vaccine against Zika, but this is the first widespread use of it. And the results have been incredible, in terms of both the speed of the vaccines' development and their efficacy. When we saw the reports from early testing of the Pfizer/BioNTech vaccine, I was amazed; indications were that the vaccine was between 90 and 95% effective! For comparison, the annual flu shots that many of us receive vary in efficacy from year to year but are generally between 40 and 60% effective.

Additionally, mRNA technology positions us to quickly produce new vaccine versions to combat viral variants that may emerge. If we discover variants of COVID that are not susceptible to the current vaccines, mRNA technology offers us the ability to rapidly create boosters or new vaccines suited to those variants. Vaccine manufacturers are already anticipating and preparing for the need to create new vaccines to address emerging variants.

Some people are concerned because the COVID vaccines have not yet received formal approval from the FDA; they are being provided under an "Emergency Use Authorization." Does that mean the vaccines may not be safe?

The FDA approval process for drugs and vaccines involves very stringent standards and can take months. However, in extraordinary circumstances, the agency can grant an Emergency Use Authorization, or EUA, to make available to the public a treatment that may be of benefit and does not show any clear evidence of harm.

It's important to understand that the COVID vaccines have already undergone a significant level of review; both the FDA and an outside panel of medical experts, the Advisory Committee on Immunization Practice, reviewed the results of the early studies and agreed that the EUA was warranted. The benefits of administering the vaccine clearly outweigh the risks and, with time being a critical factor, there really could be no doubt about the decision to proceed.

I know that people are being asked to sign a release acknowledging that they understand the vaccine is not yet FDA approved and is being provided under an Emergency Use Authorization, and this can be intimidating. But I want everyone to be assured that these vaccines would not have been made available if the best minds in the business did not believe that they are safe. There's no room for politics in the process through which an EUA is granted; this is 100% a health-based decision.

What, exactly, is herd immunity, and how does that relate to vaccination?

"Herd immunity" refers to the principle that when enough people have either been infected and recovered or are vaccinated, the transmission of the virus from person to person will be interrupted, protecting the wider population. It's about limiting the virus's ability to jump from person to person. It's hard to know for sure what percentage of people must be non-susceptible to the virus for us to say that we have attained herd immunity, but I would think that would be somewhere around 70 to 80%. I am definitely ready to stand corrected and hope that it's less than this conservative estimate.

So – how quickly could America achieve, say, 80% immunity? Let's say 10% of the population have had the infection and recovered. President Biden pledged that we would administer 100 million vaccines in his first 100 days in office, and that goal has already been surpassed. So, in early spring 2021, we have at least 130 million Americans with full or partial immunity, when you include the estimated 10% or so who have recovered from COVID-19. This is somewhere in the neighborhood of 40% of the U.S. population. That's still a long way from an 80% benchmark, but it's still a huge step in the right direction. I will say that President Biden has the right approach: This is indeed a war effort. I was heartened by his early remarks about activating the Defense Production Act and using other aggressive strategies to speed up production and distribution of the vaccines and other tools need to fight the epidemic, like personal protective equipment. This needs to be an all-out effort.

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What about the new variants we are hearing so much about?

This is what viruses do – they mutate. Not all mutations are harmful, but some can be. The variants emerging now that concern us are ones that appear to be more infectious than the version of the virus that we have been dealing with to date. That's a serious threat because it could lead to a sudden surge in cases that might overwhelm our healthcare system. Fortunately, it seems that the vaccines currently being rolled out would be effective against the variants we're seeing now. This is really a race against time. We need to get as many Americans vaccinated as possible, to stem the spread of the virus.

In the future, we may see variants of the coronavirus that call for a different vaccine formulation. As I said before, the good news is that we are technologically positioned to produce those updated vaccines when the need becomes apparent. Some have asked whether we might have to get annual COVID shots, the way we do flu shots now. That's possible, depending on how the virus behaves over time. It's a realistic probability that continued mutations may require additional vaccines. But here is a piece of good news for the longer term: What typically happens is, as diseases like this "get to know us better" by circulating through humans, they tend to become less virulent. This might suggest that, eventually, the virus that causes COVID will become more akin to its cousins that cause the common cold – having milder and less harmful effects. But in the short term we may need annual vaccinations for coronavirus, just as we do for the flu.

Finally, how have the events of this extraordinary year impacted you personally?

It's been a year at home, sitting in front of my computer for 10 or more hours a day. I sometimes find that it's hard to know what day or month it is. Without the regular, scheduled rituals that we go through every year – holidays, vacations, and so forth – time just sort of runs together.

The good news is that my husband and I are getting along better than I ever thought we could under these circumstances! I think our relationship has been strengthened, if anything. We go bike riding on the weekends and do some walking, but for me personally, the lack of regular exercise has been hard. I like to swim; I like to work out at a gym. But these things haven't been available. So, like everybody else, I've just been doing the best I can to adapt.

From a professional standpoint, I will say that the past year has been quite frustrating at times. Things were happening and we knew the right thing to do but were precluded from doing it. On the other hand, it's been wonderful to see the vaccines come out quickly and begin to get into arms. And we now have data that show that community mask use is helping to drive down the rate of infection. When we're able to make a difference like that, it's really satisfying.

So this is what we epidemiologists do. When a disease outbreak first emerges, we don't know anything about it – all the ways it's transmitted, how best to respond in terms of prevention or treatment. But we learn. We do investigations. We look for patterns. We make our best, informed guesses, then we observe and measure the results. Our currency is helping to make good a priori judgments, paying attention to the scientific data as it starts to come in and, as our knowledge grows, making adjustments accordingly.

I'm really interested to see where we are a year from now. A year ago, I went to a Korean supermarket here in Atlanta and saw people wearing masks, which is common in some Asian cultures when people think there may be risk of illness. It seemed odd to see that at the time. now, when we see people not wearing masks in public places, that seems odd. Think of how we've changed, how our perceptions and priorities have shifted. We have a whole generation of kids who are now used to wearing masks in public and doing school via computer. A huge number of adults have now experienced working without physically going to their traditional workplace. Not to mention all the ways the pandemic has affected our behaviors with respect to shopping and entertainment and dining out and simply interacting with other people. I am interested to see the lingering effects of this experience on our behavior and our culture.

Interestingly, there has been almost no flu in the United States this year and pretty low rates of other viral respiratory infections. That suggests that all the things we're doing in response to COVID are also preventing the spread of flu and these other illnesses. I think when people walk away from this experience, we will see some good things come out of it. We have to acknowledge the painful and historic toll of this pandemic. We will talk about 2020 for many years to come. But I also know that we have learned, and will continue to learn, things that will make our lives better and prepare us for future challenges.