Category Archives: Vaccines

Episode 60: Saad Omer On Translating Vaccine Science Into Policy

Photo by Kay Hinton

Translating science into policy is challenging, especially when it has to do with vaccinating pregnant women and other vulnerable populations. Our 60th podcast features Dr. Saad Omer (MBBS, PhD, MPH), vaccinologist at Emory University, who is also involved in several working groups to translate vaccine science into evidence-based policy at the National Vaccine Advisory Committee, The World Health Organization, and at the Pan American Health Organization. While Saad has a large research portfolio, he is most known for his trials to estimate efficacy and immunogenicity of maternal and/or infant influenza, pertussis, polio, measles and pneumococcal vaccines. In 2009, he was awarded the Maurice Hilleman award in vaccinology by the National Foundation of Infectious Diseases on his work on impact of maternal influenza immunization on respiratory illness in infants younger than 6 months- for whom there is no vaccine.

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Episode 57: Mary Carol Jennings On Accelerating Vaccine Access

How does Johns Hopkins International Vaccine Access Center (IVAC) help speed up equitable access to life saving vaccines like rotavirus or HPV vaccines? Mary Carol Jennings, MD, on top of being drawn to community medicine, has always felt a calling for advocacy and bringing positive change to her surroundings. Even through her rigorous medical training, she made time for helping others at all stages of her career. At IVAC, Mary Carol is lead on two projects: RAVIN, an accelerator project for equitable vaccine access to rotavirus vaccine, and developing a new project on HPV vaccine access and advocacy.

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Episode 52: Kate O’Brien On Vaccines & Social Justice

This week, Nina is joined by International Vaccine Access Center (IVAC at Johns Hopkins School of Public Health) Advocacy and Communications Specialist Swati Sudarsan as they interview Kate O’Brien, Executive Director of the International Vaccine Access Center. Did you know vaccines can address social justice? In this episode, Kate explains that the children around the world who have the least access to vaccines suffer the most from vaccine preventable diseases – but she aims to change that. First on her list is an evaluation of the full benefits of vaccines, in an analysis she calls the “full public health value of vaccines.” She explains that vaccines not only prevent disease in an immunized child, but it can protect the people around them, can help families avert the costs of hospitalization from disease, and can even reduce an emerging crisis – antibiotic resistance.

Kate is a sitting member of the Strategic Advisory Group of Experts (SAGE), which advises the World Health Organization on global vaccine policy, and serves on the Gavi Board representing the Technical and Research constituency. She is a senior advisor at the Center for American Indian Health, and of course, a beloved professor in the Department of International Health at the Johns Hopkins Bloomberg School of Public Health.

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A special thank you to Swati Sudarsan and Rose Weeks from IVAC for production help.

Episode 51: Peter Hotez on Vaccine Hesitancy


Last time on PHU Podcast, we spoke about vaccine confidence with Heidi Larson and Pauline Paterson. On our latest podcast, Nina speaks with Dr. Peter Hotez on a related topic: vaccine hesitancy. Vaccine confidence and hesitancy are related but different issues. Think: opposite sides of the same coin. Vaccine hesitancy describes the idea that people are unsure about whether to get vaccinated (and they may be pro- or anti-vaccine). According to the WHO, vaccine hesitancy is caused by any of the 3 C’s: complacency, convenience and confidence. Note that this only refers to scenarios in which vaccines are readily available to the person.

Peter Hotez is well known for his science communication and advocacy efforts on vaccines–which have been motivated and inspired both by his daughter, who has autism, and his long research career in vaccine development for neglected tropical diseases.  Peter is has a long list of jobs including:

  • Founding dean  at the National School of Tropical Medicine
  • Professor of Pediatrics and Molecular Virology & Microbiology at Baylor College of Medicine
  • Texas Children’s Hospital Endowed Chair of Tropical Pediatrics
  • Director of Texas Children’s Hospital Center for Vaccine Development
  • Baker Institute Fellow in Disease and Poverty at Rice University.
  • Co-founder, Global Network for Neglected Tropical Diseases in 2006 as part of the Clinton Global Initiative.
  • Founding Editor-in-Chief of PLOS Neglected Tropical Diseases
  • 2014-2016 United States Science Envoy

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Podcast 50: The Vaccine Confidence Project with Heidi Larson & Pauline Paterson

Vaccine Confidence Project

We had a transatlantic, bi-coastal three way Skype podcast last month with researchers Drs. Heidi Larson and Pauline Paterson who co-direct the Vaccine Confidence Project at the London School of Hygiene and Tropical Medicine.

Heidi LarsonPauline Paterson

Heidi and Pauline are globally respected and known for this unique, extensive, and broad research into understanding how we can boost the global community’s confidence in vaccines. A large piece of their work is profiling conversations from around the world and to pinpoint factors that lead to confidence or not. The other side of this coin is the term ‘vaccine hesitancy’ that describes why people do not feel confident in vaccines (a person can still vaccinate their child, but still be vaccine hesitant).

Please note: Most of this podcast has good audio quality, however, due to the Skype connection, had a few moments here and there of poor connectivity. The PHU wizards did their best to provide the best quality, please be patient as we continue to improve our Skype recording process.

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Podcast returning next week!

We are pleased to let you know that the PHU podcast will be starting up again next week! I will be discussing vaccine hesitancy with Drs. Heidi Larson and Pauline Paterson who co-direct the Vaccine Confidence Project via London School of Hygiene and Tropical Medicine (among many other cool things!).

Thesis Me Pic
Dr. Nina in the house!

It’s been a long time since the last podcast, but with good reason: on September 1st, I successfully defended my doctoral thesis in molecular microbiology & immunology. I also have completed two manuscripts for publication over the summer. Other great things I was up to:

Summar Collage Pix

  • Got a job! Starting soon: associate at the International Vaccine Access Center on the Policy, Advocacy, and Communications Team! Learn more about IVAC on this podcast with my new boss Lois. Or listen to Bill “heartthrob” Moss here and here.
  • Fellow, New York Academy of Sciences Science Alliance Leadership Training – July 2017. Five days of leadership training at the Academy. Met so many great people and learned so much about myself, how I function in group settings, and things to work on to become a better leader (and group member).
  • Oral presentation, American Society for Microbiology Conference for Undergraduate Educators – gave a ‘microbrew’ talk on my scicomm course. Fantastic conference in Denver, Colorado with fellow educators interested in improving science teaching methodologies. I can’t wait for next year already! July 26-August 1.
  • Completed Teaching As Research Fellowship: June 2017. Completed this yearlong fellowship that provided training and resources to research the effectiveness of my teaching methods in my course, “Communicating Science.” Presented on June 30 at Johns Hopkins University.
  • Awarded Gordis Teaching Fellowship: Johns Hopkins School of Public Health teaching fellowship to design and teach a course to public health studies undergraduates at Johns Hopkins. Taught self-designed course “Communicating Science: Skills to Analyze and Communicate Science News”. Awarded for three semesters: Spring 2016, Fall 2016, Spring 2017.
  • Instructor, Introduction to Biomedical Sciences, August 2017. Taught three classes as part of Dr. Gundula Bosch’s intensive summer course for incoming JHSPH graduate students. Sessions taught: Science Communication, Molecular Biology, Musculoskeletal System, Cardiovascular System. This was my fourth year co-teaching this course and always meet so many fantastic new students.
  • Invited speaker, JHSPH Molecular Microbiology & Immunology Postdoc Forum. July 2017. Science Communication.
  • Invited speaker, Mississippi State University, September 2017. The anti-vaccine movement.
  • Completed Johns Hopkins Teaching Academy “Preparing Future Faculty” Certificate Program, Johns Hopkins University, September 2017. This certificate program provides training in teaching methods for Hopkins graduate students and postdocs. Check out here.

Episode 40! Lois Privor-Dumm On Vaccine Policy & Advocacy Communication


Nina gets to do her favorite thing on the latest episode: talk about vaccines! Nina is back over at the International Vaccine Access Center with Director of Policy and Advocacy Communications Lois Privor-Dumm. Lois has been working on vaccine advocacy for decades to bring life saving vaccines (like the one to prevent meningitis) to countries all over the world.

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Special Halloween podcast! On BS…aka Science Policy of the Presidential Candidates

Nina and Kenny
Nina and Kenny

Happy Halloween! Four scientists get together on Halloween to talk about a spooky topic: the science views of the presidential candidates! The science communication show Public Health United welcomes Dr. Bill Moss (see our previous podcast together), Dr. Katherine Fenstermacher (Hopkins), and Kenny Shatzkes (Rutgers, Eagleton Fellow) to talk about their frustration while watching the debates, the lessons they’ve learned in communicating science and policy, and how scientists and policymakers need to collaborate and reach compromises to form better science policies. I cannot even count the number of laughs we all have together. Truly a fun and informative episode on science policy during this election season! FYI, the title of this special edition podcast is based on Harry Frankfurt’s NYT best selling book, “On Bullshit” which details the difference between liars and bullshitters…listen to hear what the difference is and how destructive the latter can be!

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Get In The Game: Vaccine Communication with Dr. Paul Offit


I had the pleasure of visiting my old work place and interviewing Dr. Paul Offit, vaccine communicator and researcher at Children’s Hospital of Philadelphia. What ensued was a very stimulating and often times LOL kind of conversation. I am very thrilled to share this insightful podcast with a leader of scicomm (an often extremely difficult role).

Paul Offit

Download the podcast here or access on iTunes here.

Show Links:
Paul Offit at Children’s Hospital of Philadelphia
Children’s Hospital of Philadelphia Vaccine Education Center
List of Paul Offit’s books on Amazon
Information on rotavirus vaccines
Link to Paul Offit’s free vaccine course on Coursera
Watch Nina at Ignite Baltimore speaking on vaccine communication issues
PBS/Frontline Article: The Vaccine War



Vaccine Concerns: Synthesis of Vaccine Viruses (Ingredients Part 2B) by Nina Martin

After reading Part 1 and Part 2A, you should now understand why we use medium, FBS, and antibiotics to grow cells and that it’s important to passage cells if you want to continue or expand your cell line. We also discussed fibroblast cells and how they are typically used in the lab because they are easy to grow and you can expand your cell line into multiple flasks rapidly. These concepts are absolutely vital in understanding how vaccines are made.

Let us move on to the next big concept in vaccine manufacturing: attenuation of the virus. You may have already heard the term attenuate. For example, the measles vaccine is a live, attenuated vaccine. What does this mean and how does this fit in with our ingredients list?

To attenuate means to weaken; to attenuate a virus means to weaken it. Remember that for an efficacious vaccine, we want to expose people to the germ and activate the immune system without causing illness. In the lab, scientists have figured out how to change the measles virus so it will still activate your immune response, but not actually make you sick. Here’s how:

Virus attenuation via adaptation into a new host cell. 1. Sample is taken from host. 2. Passaged through chick embryos multiple times. 3. Passaged through chicken embryo fibroblasts multiple times. 4. Attenuated virus is isolated from cells and sequenced.

Wild measles virus is well suited for human cells: once you breathe it in, measles will invade your lung (epithelial) cells, take over its machinery, and reproduce itself. A scientist name Enders first discovered that if you add measles virus to non-human host cells, like chicken egg (embryo) cells, the virus will adapt (aka mutate) to its new host. This is survival of the fittest at its best! Please note that the measles vaccine virus used in MMR is passaged in chicken embryo fibroblast cells and not in eggs.

Measles attenuation
Diagram of how measles virus was attenuated. Key: Names within the colored boxes are the names of the measles strains. 1. Measles virus was isolated from a patient with last name Edmonston. 2. The Edmonston strain was serially passaged 24 times in human kidney cells, 28 times in amnion cells, 6 times in chick embryos, and then in chicken embryo fibroblasts to create the Edmonston B strain. The current measles vaccine virus in the U.S. (Attenuvax, Merk) was made by further attenuating the Edmonston B strain 40 times in chicken embryo fibroblasts. We call this live, further attenuated virus the Moraten or Edmonston-Enders strain.  The Schwarz strain, made by attenuating the Edmonston A strain, is widely used in vaccines in Europe and other countries around the world.

 By repeating the process of adding virus to cells, letting it grow, then isolating the virus and adding it to a new plate of cells, over time you can create a virus that is so well adapted to surviving in its chicken host that it can no longer efficiently reproduce in the human host. We call this process passaging the virus in cells or tissues. Please read our previous article for a nice summary of how we passage cells in the lab. The measles vaccine virus is passaged in chicken embryo fibroblasts while other vaccine viruses, like rubella, is passaged in other host cells like monkey kidneys or human diploid cells (more on this in a bit). Theoretically any cell that is not the typical cell for measles invasion could work–though some viruses will not grow at all in certain hosts. It’s important to know that we passage the virus at least 40  times (or even more depending on the specific vaccine) in chicken embryo cells. This is necessary (and great) because when you give the attenuated (weakened) virus back to the human host, there is only an extremely small chance of it reverting back to the wild virus—each round of passaging created a new batch of mutations that helped the virus survive in the chicken. It is almost impossible for the virus to jump back to the human-disease causing form.

Rubella attenuation
The rubella virus vaccine strain currently used in the U.S. in the MMR vaccine (Meruvax II) was created by serially passaging rubella virus in WI-38 cells at a low temperature (for viruses). Growing the virus in the diploid cells at low temperature resulted in the production of the avirulent (attenuated) strain RA 27/3.  Two other strains were previously used in vaccines in the 1960’s and 70’s (HPV-77 & HPV-77/DEC but were continued due to side effects and because they didn’t provide as much protection as the RA 27/3 strain did.

 So now when you see non-human cells listed in the vaccine package insert, you know why: wild virus is passaged in non-human cells many times, forcing it to adapt to the new host and no longer causing disease in the human host.

Common concern: Use of chicken embryo fibroblasts to passage virus Some people have legitimate concerns about vaccines that are prepared in chicken embryos. After isolating the virus from the egg, there still could be a small amount of chicken proteins that some people have an allergic reaction to (i.e. when you get redness and other symptoms from the flu shot). Viruses that are grown in chicken fibroblast cells (not in the egg, just in cells) do not experience an allergic reaction because the virus was never in the whole egg. So even though the measles vaccine is grown in chicken fibroblast cells, there is no reported evidence of having an egg allergy to this. Another concern is the use of chicken embryos in general. Often when people hear the word embryo, they do not realize that we mean a chicken egg. So if you don’t have an issue with eating chicken or egg products, there should also be no issue with this process. However, some people are ethically against the use and/or consumption of animals, period, and thus this is a legit concern to have. Unfortunately, we don’t have a better way to mass produce the amount of virus needed for vaccines and other research purposes. Some researchers are currently working on genetically engineering attenuated viruses and others are working on alternatives to animal testing. But these standard practices are currently the most reliable tools we have.

Common concern: Use of human fetal diploid cell lines to passage virus Let’s get some definitions out of the way. You may see the term ‘human diploid cells’. Diploid refers to the number of copies of chromosomes found in a cell (di = two). If you remember from science class, most cells of the body, besides your sex cells, are diploid. So nothing out of the ordinary there. Second, I’ve observed online that some people are confused about the term “cell line.” A cell line is a cell culture developed from a single cell and therefore consisting of cells with more or less identical genetic makeup. You can propagate some cell lines indefinitely. This is important to understand because we can isolate cells from a tissue once and then culture them for decades–we don’t isolate cells from new tissues over and over again. There are two cell lines that were first created in the 1960’s that are used to make some vaccine viruses and were originally derived from two human fetuses called Wi-38 and MRC-5. Both the Wi-38 and MRC-5 cell lines are composed of fibroblast cells from lung tissue. I’ve observed some confusion online regarding the synthesis of these cell lines: some people think fetuses are sacrificed every time this cell line is used. It’s important to understand that this cell line was made in the 1960’s from two fetuses that were already destined for abortion. The parents agreed to donate the fetuses for research at the time of termination. Others are concerned about the religious implications of using fetus cells in vaccines. First, some people are under the impression that you can find fetus cells in the final vaccine product. This is not true: the virus is isolated from the cells and washed several times. Second, the Vatican has issued a statement several years ago that is it acceptable to use vaccines that were prepared with these cells as it serves for the greater good. They also ask for better methods of vaccine manufacturing that will avoid using these cell lines. Asking for better methods is definitely a great suggestion, just remember that you need to support science funding in order for that to happen! Please read this article for more information about the cell lines used and the religious implications.

Common concern: vaccines contain cells (whether they be human, animal, other)
Please note that viruses are removed and purified from cells before vaccine manufacturing. You will see on some package inserts that residual amounts of cellular products MAY be found in the final product. I am personally not concerned about this after reading Plotkin’s article here and knowing that we consume plant and animal cells at a much larger rate than the miniscule amount found in vaccines. The vaccine product is also extensively tested and scanned for any dangerous contaminants before release.

If you read the previous articles, I hope you can see that production of the vaccine virus is separate from production of the final vaccine product that is injected into you. This means that the ingredients we have discussed so far, including animal and human cell lines, are not found in the final product (except possibly in amounts less than 1 ppm).  In the next article, we will get into how the vaccine virus is packaged into the vaccine product and what ingredients are actually found in the injectable form.

Photo credits:
Figure 1. Virus Attenuation. Taken from:
“Attenuation of measles strain” diagram modified from Plotkin et al. “Vaccines.” (textbook). Philadelphia: Saunders; 2012.

Plotkin et al. “Vaccines.” (textbook). Philadelphia: Saunders; 2012.
Plotkin. “The history of Rubella and Rubella vaccination leading to elimination.” Clin Infect Dis. (2006) 43 (Supplement 3): S164-S168.
Hilleman et al. “Live, Attenuated Rubella-Virus Vaccine.” N Engl J Med 1968; 279:300-303

Please let me know if you spot any inaccuracies in this text at