May 3, 2021


#160 – Paul Offit, M.D.: The latest on COVID-19 vaccines and their safety, herd immunity, and viral variants

“If you ask me the question, ‘What do I fear most about this whole pandemic?’ it's actually not the variants. ... It's that there would be a significant percentage of the population that is going to choose not to vaccinate so much so that we can't get to that 80+% of population immunity we need to slow this virus.” —Paul Offit

Read Time 24 minutes

Paul Offit is a pediatrician specializing in infectious diseases and an expert in virology and vaccine development. He currently serves on the FDA committee evaluating COVID-19 vaccines. In this episode, Paul’s second appearance on The Drive, he provides an update on all the SARS-CoV-2 vaccines currently deployed, explains why the concerns raised around the mRNA vaccines are not legitimate, and offers his view on the prospects and timeframe of reaching herd immunity. He also takes a deep dive into immunology, explaining the short-term and long-term immune response to both natural infection and vaccination and how these two can function together to provide durable immunity. Additionally, they discuss the theories on the origins of this virus, what impact the new COVID-19 variants might have, and the recent pausing of the J&J vaccine. Finally, they discuss how we can be better prepared for an inevitable future outbreak of a novel virus. This episode was originally recorded on April 14, 2021.



We discuss:

  • Overview and current status of the SARS-CoV-2 vaccine strategies [4:10];
  • Addressing concerns about mRNA vaccines [9:00];
  • How the failure to make an effective HIV vaccine aided the development of a COVID-19 vaccine [16:45];
  • Where SARS-CoV-2 falls on the spectrum of its ability to mutate and what that means for immunity and vaccination [21:30];
  • How the combination of short-term and long-term immune response to SARS-CoV-2 work together to provide durable immunity [28:00];
  • Importance of understanding relative vs. absolute risk reduction [38:15];
  • Implications of pausing the J&J vaccine due to reports of blood clotting in the brain [42:45];
  • What constitutes herd immunity and the concerns of rising vaccine hesitancy [47:45];
  • When we might reach herd immunity, future vaccines for children, and long-term outlook for maintaining population immunity [58:45];
  • Theories about the origins of SARS-CoV-2 [1:07:00];
  • Preparing for the possibility of a future pandemic and how we can learn from our mistakes [1:10:40]; and
  • More.


Overview and current status of the SARS-CoV-2 vaccine strategies [4:10]

This interview includes a discussion of several different kinds of vaccines. Here is an overview of the various types of vaccines:

Figure 1. Overview of vaccine types. Image credit: McGill University COVID19 Vaccine Tracker

  • Tens of millions of people have now been vaccinated against SARS-CoV-2

Specific types of SARS-CoV-2 vaccines

Figure 2. Types of COVID-19 vaccines. Image credit: Wellcome

  • 1) mRNA is the farthest along in the US
    • FDA granted EUA to Pfizer on Dec 10 and Moderna on Dec 17
    • 120 million have received at least one dose of one of these
  • 2) Adenovirus
    • Uses adenovirus as a vector to deliver viral DNA
    • Jenner Institute/Astra Zeneca (AZ): replication-defective adenovirus vector
      • Tens of millions of AZ in UK and Europe
    • Janssen / Johnson & Johnson (J&J): replication-defective adenovirus type 26
      • 200K in west Africa for Ebola
      • more than 6 million in US for SARS-CoV-2 
    • 20 million + doses of these vaccines
    • Russian vaccine is also a replication-defective adenovirus vaccine (human Ad26 followed by human Ad5)
  • 3) Purified protein
  • 4) Live attenuated
    • still in the works
    • Paul doesn’t think one has been approved anywhere
  • 5) Whole killed viral vaccine
    • Used in China on 10+ million people
    • Similar to how we make vaccines for polio, rabies, Hep A, etc. 
    • some question how well it works against SARS-CoV-2
    • Whole killed virus was first used in late 1800s by Louis Pasteur against rabies
  • The first vaccines were live non-human viruses
    • Used cowpox in late 1700s
    • The virus was close enough to human smallpox that produced immune response
    • but they didn’t understand the science behind it back then


Addressing concerns about mRNA vaccines [9:00]

  • People say mRNA is experimental and like science fiction
    • Peter has tried to point out it’s not as experimental as people think and has been around for decades
    • Now is just the first time we did the final step of sequencing and putting it into clinical practice

{end of show notes preview}

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Paul Offit, M.D.

Dr. Paul Offit is a pediatrician specializing in infectious diseases and an expert on vaccines, immunology, and virology. He is the co-inventor of a rotavirus vaccine that has been credited with saving hundreds of lives every day. Offit is the Maurice R. Hilleman professor of vaccinology, professor of pediatrics at the Perelman School of Medicine at the University of Pennsylvania and director of The Vaccine Education Center at  Children’s Hospital of Philadelphia (CHOP). Dr. Offit is currently a member of the National Institutes of Health (NIH) working group on vaccines, a subgroup of the Accelerating COVID-19 Therapeutic Interventions and Vaccines (ACTIV) project that is planning a strategy to combat COVID-19. He is also a member of the FDA’s Vaccines and Related Biological Products Advisory Committee (VRBPAC). Previously, he was a member of the Centers for Disease Control and Prevention’s (CDC) Advisory Committee on Immunization Practices. Dr. Offit is a board member of Vaccinate Your Family and Autism Science Foundation and the author of eleven books.


Twitter: @DrPaulOffit

Facebook: Paul Offit

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  1. I am a doctor and the talk of vaccine mandation in this podcast made me sick to my stomach. Medical autonomy is a fundamental RIGHT. Not a privilege. A Right.
    It doesn’t matter whether you might affect or not affect other people. You simply CANNOT force people to take medication they don’t want to. If we care so much about society’s health and wellbeing, why don’t we START with the junk food companies, polluters, big tech etc that are collectively destroying everyone’s health?

  2. Thank you Peter and Dr. Offit for an informative discussion, though rather limited in scope in some ways – understandably.

    I would have preferred a little more on the origins of this virus which has killed over 3 million people in the world already, some of them close to me, so the pain is real.

    I do understand Dr. Offit works for the government and thus has to toe the party line about it ‘not being of lab origin’, but his argument sounded a bit disingenuous.

    I would also have liked some mention of India and its own vaccine development with an inactivated virus. As of date, India has vaccinated more people than the US has and it is the only country to have sent free vaccines to many nations that could not afford the ones from Big Pharma.

    Sadly though, like so many other things, this horrible scourge has become a political football.

    Pradeep Bansal, MD

  3. I just finished listening to episode 160. What I did not hear discussed was other than vaccines, what should we do to help mitigate this virus. It is well known that the metabolically unstable are more likely to suffer serious consequences, or in general get the disease. So, how about putting out an education campaign on how type II diabetics, high blood pressure sufferers, etc. can cure their metabolic disease by cutting unhealthy carbohydrates, which will make them much less likely to become infected. It seems as if we always default to a shot or pill.

    I find this discussion to be a conflict of interest for Paul Offit because he currently serves on the FDA committee evaluating COVID-19 vaccines. He has to support the use of the vaccine. Also, this vaccine was approved for EMERGENCY only use so technically I believe it is not through final approval. The country is no longer in an emergency state.

    There was a podcast that I recently listened to involving 3 researchers (2 physicians) and they laid out all the possible side effects of taking any of the Covid Vaccines. Here is a link to an article and a 3 hour long video. I recommend you take the time to read and watch this very eye opening information: I just found out YouTube took the video down due to what they call violating community guidelines.

    Finally, I frequently heard, I think, in my opinion… Forcing someone to take a vaccine is against our rights as a US citizen.

  4. Mandates don’t have to be highly authoritarian orders in the cartoonish manner portrayed by the uneducated and the willfully ignorant anti-vaxers and their evil manipulative profiteering puppet masters. Incentives will do. Like: stay out of our schools, our pubs, our buildings. Our buses. Our planes. If you want to reject vaccine technology and live like a cave man, live in a cave. Yes, this COULD be carried too far, to an extreme. But in this case, it is not. Covid can mutate and get worse. This is not “forced medication” – which occurs more often probably than it should. Covid vaccine incentivization is not forced and is not the terrible injustice its critics claim. This is really a global emergency it is the duty to get people vaccinated asap and people who obstruct that harm us all.

  5. Thank you for this educational piece Dr. Attia. I believe that another portion of population that isn’t getting vaccinated is because of the language barrier and low income/resources to education. I have used some of the information on this podcast to share it in spanish to my community in Omaha. You can see it at:Watch “Bonita Omaha ep 77” on YouTube

  6. I have been a podcast listener and bit of a follower of Dr. Attia’s for some time. While I do not always agree with his views, the majority of time I think that he gives reliable advice with integrity and interviews people of integrity. This, however, is the exception, and it appears that Dr. Offit has been interviewed twice on this podcast. I read a very interesting interview Dr. Offit did with the MedScape editor in Oct. 2020, where he stated, among other things that did occur even though he expressed concern about them, that the FDA would never approve a vaccine for use in a population not included in a clinical trial( those >65, children, and African Americans), and yet that is exactly what has, unfortunately happened. He is a PR mouthpiece for the safety of vaccines, while at the same time has been questioned for conflict of interest violations when he voted for the recommendation of the rotavirus vaccine on three occasions, while he was developing a rotavirus vaccine with Merck. I am sorry to say that I question Dr. Offit’s integrity and have a difficult time trusting what he says on this podcast.

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