The infectious positivity of Mario Barro
The infectious positivity of Mario Barro
Rapport special correspondent (and RA Capital Strategic Counsel) Sarah Reed sat down with RA Capital Head of Infectious Diseases Mario Barro, PhD, to discuss his circuitous journey from growing up in Havana, Cuba, to nuclear physics in the USSR, to becoming RA Capital’s head of infectious diseases and GIVAX’s chief executive.
Mario, when people introduce you and start to say “infectious”, I’m like “yes!” and keep waiting for them to follow that with “personality” but every time they go on to say “disease expert.” What’s your secret to being so upbeat all the time?
Thank you for the compliment. The answer is actually quite simple. I grew up in a country where science was valued, yet basic freedoms were hard to come by. Today, I enjoy both freedom and material comfort – and I get to spend my days not chasing basic human needs, but pursuing genuinely challenging intellectual problems. It feels like a childhood dream come true. I am grateful every waking hour, because I remember the struggles well.
Where did you grow up?
I grew up in a poor neighborhood of Havana, Cuba. My grandparents from mom’s side had fled the countryside because my grandmother's family disapproved of their marriage. They arrived in the city with nothing. My grandfather started as a laborer and coffee roaster, eventually building his own coffee shop, until the revolution came and took it from him. He was an awesome man with a sweet character that never changed despite the many difficulties he faced. I got my love for coffee from him.
My father was a remarkably curious man who reinvented himself several times over – surgeon's assistant, physics teacher, economist, restaurant owner. He gave me something invaluable: the belief that it's okay to change direction, to move from one field to another. That mindset has shaped everything about my career.
When and how did you first become interested in science?
From early childhood, I was drawn to mathematics and fascinated by explanations of how the natural world worked. My father and I would spend time together running simple experiments from an old science book we kept at home – those moments stayed with me.
Cuba, despite its political oppression, had a genuine commitment to science education. The revolution expanded access to schooling in marginalized areas, and that gave kids like me a real chance to excel. Because of that, at around age 14, I was accepted into a cohort of 75 students at Cuba's elite magnet high school for science, for a rigorous program centered on mathematics, physics, and chemistry.
That education changed how I saw the world. The scientific method taught me to question everything. I remember asking my parents around that time: "If socialism is so much better than capitalism, why aren't we winning? Why are we worried about losing?"
From there, I went on to study nuclear physics in the former Soviet Union – the best program available to a kid like me. It was an adventure, but not an easy one. I was away from home for almost five years, contacts with family were infrequent, and I had to learn a new language in a very foreign place. Interestingly, I was there in Byelorussia when Chernobyl happened. Many of my Nuclear Physics professors went to Ukraine as part of the urgent scientific response to the crisis.
How did you make the transition to life sciences?
When the Soviet Union collapsed, I was called back to Cuba. The nuclear program had depended heavily on Soviet support, and when that disappeared, so did any prospect of a job in my field. I found myself doing whatever work I could find – tire repair, teaching, security work.
The turning point came when Castro's Center of Biotechnology and Engineering, established in the late 1980s to build Cuba's biotech industry, began hiring. There weren't enough young Cubans with the right academic background, so they were willing to train people on the job. I wanted to stay in science. Friends from that Institute explained to me what biotech work was, and I read some books. I became fascinated one more time and joined the Center in 1991.
The work was intense by any measure. Days ran from 8 AM to 11 PM. We ate all our meals at the Institute. I was earning less than $2 USD a month. And yet I considered myself fortunate because the economic reality outside those walls was far grimmer. Young women with medical degrees were turning to sex work to survive. Taxi drivers held degrees in engineering or nuclear physics. The country was in freefall, and biotechnology was one of the few places where there was still something purposeful to do.
Was science independent of politics in Cuba?
Not at all. Everything at the Biotech Institute had a strong connection to the government. Anyone caught showing dissent was ostracized or removed from projects. And the consequences didn't stop with the individual. Politics shaped public health decisions too.
I witnessed this firsthand during the Cuban neuropathy epidemic of 1993. I was working at a molecular biology lab focused on hepatitis C when, seemingly out of nowhere, tens of thousands of Cubans began losing their vision, suffering acute nerve pain, and in severe cases, losing the ability to walk.
The Soviet collapse put Cuba into an economic tailspin, and the government was desperate to deflect blame. Food shortages and malnutrition were obvious contributing factors but saying so was politically dangerous. A health minister had already been removed for suggesting it.
Instead, the government pushed a viral explanation and my lab was among those repurposed to find it. We were given samples, no controls, and we were under enormous pressure. We worked day and night, reporting results directly to political leaders, including Fidel Castro himself. We found fragments of viral-like sequences in spinal fluid, but the data didn't hold up. There was no clear transmission, no consistency, no real association. Deep down, many of us suspected the truth: this wasn't an infection. It was malnutrition. But saying that aloud was unthinkable.
I’ve written before about the arrival of a team from the CDC led by David Freedman, and how they were able to get to the truth. This wasn’t caused by a virus, it was caused by a vitamin deficiency. Even a dictator couldn’t dismiss what the US CDC was saying, and within weeks Cuba ended the health crisis with vitamin supplements. That was a powerful example for me. The CDC came in using science to get to the truth without regard for politics and saved lives.
I thought it was virtually impossible to leave Cuba – how did you escape?
By that point, I had become deeply radicalized against the government, though I had to keep those feelings carefully hidden, given how tightly the state controlled everyone working at the Biotech Institute. I knew I had to find a way out, but I also knew I had to be patient and strategic about it.
My first move was to transfer somewhere with less intense government oversight. I found a position at the Oncology Institute, which had far less political relevance largely because it had no funds to run experiments. Less visibility meant more room to maneuver.
The escape plan itself came from a friend who was working at the University of Chile. He had a professor there send a fax to my institute describing, in very specific terms, the type of scientist they needed for a scientific collaboration. He had reverse-engineered the description to fit me perfectly. It was clever in a way that only someone who understood how the system worked could appreciate because the leaders of my institute came to me and urged me to take the opportunity on behalf of the institute. They thought they were sending me on a mission. In September 1996, I arrived in Santiago.
And how did you manage to stay in the biotech field after emigrating?
Chile gave me a foundation I couldn't have anticipated. The University of Chile accepted me as a PhD student, and I earned a degree in Biological Sciences with a focus on microbiology through an excellent program supported by the German Academy of Science. From there, I came to New York City for a postdoctoral fellowship at Mount Sinai School of Medicine, working in bioinformatics and structural biology, followed by a second postdoc at NIAID/NIH focused on innate immune responses to viral infections.
Those eleven years – from Santiago in 1996 to the US in 2007 – were the years that made me the scientist I am today.
From there, my career took me to a non-profit vaccine company in Research Triangle Park, North Carolina, where I led a team of fourteen people working on adjuvants, mucosal immunity, and vaccines, supported by two NIH grants. Then came BARDA, where I learned vaccine development from some of the most experienced people in the field. They were ex-pharma veterans working at the frontier of pandemic preparedness, with real resources to deploy. And then Sanofi, where I joined a new group combining machine learning and AI with vaccine design to develop a next-generation influenza vaccine. I was blessed by the team we called FluNXT and the leadership group we had there. Very dedicated people with an incredible desire to improve one of the most important vaccines we have.
Aside from being our role model for living with a grateful heart, you are also our infectious disease expert here at RA Capital. So let’s indeed talk about that for a bit. What brought you to the firm?
My journey at RA Capital began during the COVID pandemic, when Peter Kolchinsky suggested the idea to create a vaccine team inside the firm. What drew me in was RA’s awesome team and the platform itself – the money followed the science whether that meant forming a new company or investing in an existing private or public company. No constraints except scientific validity and a good business case that a product would be valued for solving an important problem. That flexibility is rare. At the beginning it was a lot of COVID related investment as we were still in the middle of the fight against the virus. The vaccine team was the first team built at RA Capital with a single-indication focus. It is rooted in the leadership belief that vaccines are one of the most powerful public health interventions. During the first two years we went from the frantic “everything-COVID” mindset to a full view in the vaccine space and other anti-infectives.
Q: And now you head the Infectious Disease Team. What does that mean exactly? What kinds of things do you work on?
We’ve probably evaluated nearly every infectious disease company and startup in the world and have invested in many working on vaccines. We backed Curevo, which is developing a next-generation shingles vaccine with improved tolerability, and Vaxess, which is exploring novel patch-based delivery approaches. We funded Icosavax to work on RSV and HMPV and took it public. It was later acquired by AstraZeneca. Vaxcyte is a large public holding, working on pneumococcal and strep A vaccines. RA just led the investment in ILiAD Biotechnologies to support the development and approval of a BIC Pertussis vaccine that can protect longer against infection and prevent transmission of this important disease. I helped found and now lead GIVax, a company built within our Raven incubator that uses rotavirus as a vaccine vector. That’s an approach rooted in my earlier academic work.
We study every pathogen and try to figure out the best and most practical way to tackle it. If someone is already working on it, we can fund them. If not, we might start up a program. It’s exhilarating to be able to so systematically tackle big problems. The ability to move from idea to execution, with RA's support behind you, is something I don't take for granted.
Q: You also played a pivotal role in the success of Cidara (which was acquired by Merck for $9.2 billion in a deal that closed earlier this year)?
The Cidara experience captures another dimension of the role well, in this case in anti-virals not vaccines. JNJ had licensed a long-acting flu antiviral from Cidara, a small public company, and a few years later decided to get out of infectious disease and was licensing its portfolio out. We saw the value of that molecule, called CD388, and led the investment that allowed Cidara to re-acquire rights to the molecule and continue to develop it. I joined Cidara's scientific advisory board and contributed to clinical trial design that ultimately generated data that validated the program. It was a great experience for me to have that continuity, from early diligence all the way through to development. I love that RA isn’t just investing capital but rolling up sleeves and pitching in. Cidara was able to hit the ground running.
What makes this work genuinely fulfilling is the ability to contribute at multiple levels – analysis, deal structuring, investment, recruiting teams to projects and companies, board work, designing experiments and clinical trials. But the best is seeing clinical data emerge that validates a hypothesis you believed in from the beginning. That never gets old.
The goal, ultimately, is straightforward: to help bring better prevention and treatment options to patients, while making the most of everything I have learned, for the benefit of as many people as possible. I wanted to matter. I wanted to save lives. I’m doing it.
The infectious positivity of Mario Barro
Rapport special correspondent (and RA Capital Strategic Counsel) Sarah Reed sat down with RA Capital Head of Infectious Diseases Mario Barro, PhD, to discuss his circuitous journey from growing up in Havana, Cuba, to nuclear physics in the USSR, to becoming RA Capital’s head of infectious diseases and GIVAX’s chief executive.
Mario, when people introduce you and start to say “infectious”, I’m like “yes!” and keep waiting for them to follow that with “personality” but every time they go on to say “disease expert.” What’s your secret to being so upbeat all the time?
Thank you for the compliment. The answer is actually quite simple. I grew up in a country where science was valued, yet basic freedoms were hard to come by. Today, I enjoy both freedom and material comfort – and I get to spend my days not chasing basic human needs, but pursuing genuinely challenging intellectual problems. It feels like a childhood dream come true. I am grateful every waking hour, because I remember the struggles well.
Where did you grow up?
I grew up in a poor neighborhood of Havana, Cuba. My grandparents from mom’s side had fled the countryside because my grandmother's family disapproved of their marriage. They arrived in the city with nothing. My grandfather started as a laborer and coffee roaster, eventually building his own coffee shop, until the revolution came and took it from him. He was an awesome man with a sweet character that never changed despite the many difficulties he faced. I got my love for coffee from him.
My father was a remarkably curious man who reinvented himself several times over – surgeon's assistant, physics teacher, economist, restaurant owner. He gave me something invaluable: the belief that it's okay to change direction, to move from one field to another. That mindset has shaped everything about my career.
When and how did you first become interested in science?
From early childhood, I was drawn to mathematics and fascinated by explanations of how the natural world worked. My father and I would spend time together running simple experiments from an old science book we kept at home – those moments stayed with me.
Cuba, despite its political oppression, had a genuine commitment to science education. The revolution expanded access to schooling in marginalized areas, and that gave kids like me a real chance to excel. Because of that, at around age 14, I was accepted into a cohort of 75 students at Cuba's elite magnet high school for science, for a rigorous program centered on mathematics, physics, and chemistry.
That education changed how I saw the world. The scientific method taught me to question everything. I remember asking my parents around that time: "If socialism is so much better than capitalism, why aren't we winning? Why are we worried about losing?"
From there, I went on to study nuclear physics in the former Soviet Union – the best program available to a kid like me. It was an adventure, but not an easy one. I was away from home for almost five years, contacts with family were infrequent, and I had to learn a new language in a very foreign place. Interestingly, I was there in Byelorussia when Chernobyl happened. Many of my Nuclear Physics professors went to Ukraine as part of the urgent scientific response to the crisis.
How did you make the transition to life sciences?
When the Soviet Union collapsed, I was called back to Cuba. The nuclear program had depended heavily on Soviet support, and when that disappeared, so did any prospect of a job in my field. I found myself doing whatever work I could find – tire repair, teaching, security work.
The turning point came when Castro's Center of Biotechnology and Engineering, established in the late 1980s to build Cuba's biotech industry, began hiring. There weren't enough young Cubans with the right academic background, so they were willing to train people on the job. I wanted to stay in science. Friends from that Institute explained to me what biotech work was, and I read some books. I became fascinated one more time and joined the Center in 1991.
The work was intense by any measure. Days ran from 8 AM to 11 PM. We ate all our meals at the Institute. I was earning less than $2 USD a month. And yet I considered myself fortunate because the economic reality outside those walls was far grimmer. Young women with medical degrees were turning to sex work to survive. Taxi drivers held degrees in engineering or nuclear physics. The country was in freefall, and biotechnology was one of the few places where there was still something purposeful to do.
Was science independent of politics in Cuba?
Not at all. Everything at the Biotech Institute had a strong connection to the government. Anyone caught showing dissent was ostracized or removed from projects. And the consequences didn't stop with the individual. Politics shaped public health decisions too.
I witnessed this firsthand during the Cuban neuropathy epidemic of 1993. I was working at a molecular biology lab focused on hepatitis C when, seemingly out of nowhere, tens of thousands of Cubans began losing their vision, suffering acute nerve pain, and in severe cases, losing the ability to walk.
The Soviet collapse put Cuba into an economic tailspin, and the government was desperate to deflect blame. Food shortages and malnutrition were obvious contributing factors but saying so was politically dangerous. A health minister had already been removed for suggesting it.
Instead, the government pushed a viral explanation and my lab was among those repurposed to find it. We were given samples, no controls, and we were under enormous pressure. We worked day and night, reporting results directly to political leaders, including Fidel Castro himself. We found fragments of viral-like sequences in spinal fluid, but the data didn't hold up. There was no clear transmission, no consistency, no real association. Deep down, many of us suspected the truth: this wasn't an infection. It was malnutrition. But saying that aloud was unthinkable.
I’ve written before about the arrival of a team from the CDC led by David Freedman, and how they were able to get to the truth. This wasn’t caused by a virus, it was caused by a vitamin deficiency. Even a dictator couldn’t dismiss what the US CDC was saying, and within weeks Cuba ended the health crisis with vitamin supplements. That was a powerful example for me. The CDC came in using science to get to the truth without regard for politics and saved lives.
I thought it was virtually impossible to leave Cuba – how did you escape?
By that point, I had become deeply radicalized against the government, though I had to keep those feelings carefully hidden, given how tightly the state controlled everyone working at the Biotech Institute. I knew I had to find a way out, but I also knew I had to be patient and strategic about it.
My first move was to transfer somewhere with less intense government oversight. I found a position at the Oncology Institute, which had far less political relevance largely because it had no funds to run experiments. Less visibility meant more room to maneuver.
The escape plan itself came from a friend who was working at the University of Chile. He had a professor there send a fax to my institute describing, in very specific terms, the type of scientist they needed for a scientific collaboration. He had reverse-engineered the description to fit me perfectly. It was clever in a way that only someone who understood how the system worked could appreciate because the leaders of my institute came to me and urged me to take the opportunity on behalf of the institute. They thought they were sending me on a mission. In September 1996, I arrived in Santiago.
And how did you manage to stay in the biotech field after emigrating?
Chile gave me a foundation I couldn't have anticipated. The University of Chile accepted me as a PhD student, and I earned a degree in Biological Sciences with a focus on microbiology through an excellent program supported by the German Academy of Science. From there, I came to New York City for a postdoctoral fellowship at Mount Sinai School of Medicine, working in bioinformatics and structural biology, followed by a second postdoc at NIAID/NIH focused on innate immune responses to viral infections.
Those eleven years – from Santiago in 1996 to the US in 2007 – were the years that made me the scientist I am today.
From there, my career took me to a non-profit vaccine company in Research Triangle Park, North Carolina, where I led a team of fourteen people working on adjuvants, mucosal immunity, and vaccines, supported by two NIH grants. Then came BARDA, where I learned vaccine development from some of the most experienced people in the field. They were ex-pharma veterans working at the frontier of pandemic preparedness, with real resources to deploy. And then Sanofi, where I joined a new group combining machine learning and AI with vaccine design to develop a next-generation influenza vaccine. I was blessed by the team we called FluNXT and the leadership group we had there. Very dedicated people with an incredible desire to improve one of the most important vaccines we have.
Aside from being our role model for living with a grateful heart, you are also our infectious disease expert here at RA Capital. So let’s indeed talk about that for a bit. What brought you to the firm?
My journey at RA Capital began during the COVID pandemic, when Peter Kolchinsky suggested the idea to create a vaccine team inside the firm. What drew me in was RA’s awesome team and the platform itself – the money followed the science whether that meant forming a new company or investing in an existing private or public company. No constraints except scientific validity and a good business case that a product would be valued for solving an important problem. That flexibility is rare. At the beginning it was a lot of COVID related investment as we were still in the middle of the fight against the virus. The vaccine team was the first team built at RA Capital with a single-indication focus. It is rooted in the leadership belief that vaccines are one of the most powerful public health interventions. During the first two years we went from the frantic “everything-COVID” mindset to a full view in the vaccine space and other anti-infectives.
Q: And now you head the Infectious Disease Team. What does that mean exactly? What kinds of things do you work on?
We’ve probably evaluated nearly every infectious disease company and startup in the world and have invested in many working on vaccines. We backed Curevo, which is developing a next-generation shingles vaccine with improved tolerability, and Vaxess, which is exploring novel patch-based delivery approaches. We funded Icosavax to work on RSV and HMPV and took it public. It was later acquired by AstraZeneca. Vaxcyte is a large public holding, working on pneumococcal and strep A vaccines. RA just led the investment in ILiAD Biotechnologies to support the development and approval of a BIC Pertussis vaccine that can protect longer against infection and prevent transmission of this important disease. I helped found and now lead GIVax, a company built within our Raven incubator that uses rotavirus as a vaccine vector. That’s an approach rooted in my earlier academic work.
We study every pathogen and try to figure out the best and most practical way to tackle it. If someone is already working on it, we can fund them. If not, we might start up a program. It’s exhilarating to be able to so systematically tackle big problems. The ability to move from idea to execution, with RA's support behind you, is something I don't take for granted.
Q: You also played a pivotal role in the success of Cidara (which was acquired by Merck for $9.2 billion in a deal that closed earlier this year)?
The Cidara experience captures another dimension of the role well, in this case in anti-virals not vaccines. JNJ had licensed a long-acting flu antiviral from Cidara, a small public company, and a few years later decided to get out of infectious disease and was licensing its portfolio out. We saw the value of that molecule, called CD388, and led the investment that allowed Cidara to re-acquire rights to the molecule and continue to develop it. I joined Cidara's scientific advisory board and contributed to clinical trial design that ultimately generated data that validated the program. It was a great experience for me to have that continuity, from early diligence all the way through to development. I love that RA isn’t just investing capital but rolling up sleeves and pitching in. Cidara was able to hit the ground running.
What makes this work genuinely fulfilling is the ability to contribute at multiple levels – analysis, deal structuring, investment, recruiting teams to projects and companies, board work, designing experiments and clinical trials. But the best is seeing clinical data emerge that validates a hypothesis you believed in from the beginning. That never gets old.
The goal, ultimately, is straightforward: to help bring better prevention and treatment options to patients, while making the most of everything I have learned, for the benefit of as many people as possible. I wanted to matter. I wanted to save lives. I’m doing it.