History of Vaccines Blog

November 10, 2016  Karie Youngdahl

What does the United States president-elect have to say about vaccines?

Donald J. Trump has frequently stated that he believes that vaccines can cause autism, as in the Tweets shown here. In one of the primary debates, he dialed back his criticism a bit, stating, “I am totally in favor of vaccines, but I want smaller doses over a longer period of time.” But as Tara Haelle, a blogger at wrote, “Vaccines are very precisely manufactured to include only what is absolutely necessary to induce enough of an immune response that the body can protect itself against those diseases. So a smaller dose wouldn’t protect a child. It would stick a child with a needle for no reason at all. And spreading out vaccines? That just increases the risks to the children, including leaving them more susceptible to the diseases for a longer period of time. Trump is not ‘totally in favor of vaccines’ if he doesn’t want children protected from the diseases above as early as possible.” In contrast, in 2015, Hillary Clinton Tweeted, “The Science is clear: The earth is round, the sky is blue, and #vaccineswork. Let’s protect all our kids. #GrandmothersKnowBest.”

Posted in: General, Public Health

October 26, 2016  carleyroche

During the month of October, we see pumpkins, black cats, witches, and skeletons everywhere we turn. These images remind us of costumed children, scary movies, and tasty treats. But there is a bigger history behind these images, specifically the skeleton. A symbol for death and the afterlife, sometimes positive and sometimes negative, the skeleton holds a powerful meaning across many diverse cultures. It was also once adopted by the 19th-century anti-vaccination movement to scare people, especially parents, into forgoing smallpox vaccination. Below are a few examples of skeletal images used by Victorian Era anti-vaccinators.

Posted in: Historical Medical Library, Smallpox

October 20, 2016  Karie Youngdahl

Human papillomavirus vaccination series completion will now require only two doses of vaccine for adolescents younger than 15 years. The Advisory Committee on Immunization Practices approved this recommendation at their biannual meeting in Atlanta yesterday. The new schedule for <15 year olds calls for the second dose to be given between 6 and 12 months after the first dose. Adolescents receiving the first dose of HPV vaccine at age 15 or older will continue to be recommended three doses of vaccine, given at 0, 1-2, and 6 months.

Posted in: HPV, Meningococcal disease

October 12, 2016  Karie Youngdahl

Frequent visitors to this site will probably be acquainted with the name Maurice Hilleman and the man's work. During a long career with the U.S. Army, Squibb, and Merck, Hilleman developed dozens of vaccines and made important innovations in vaccinology. Before Hilleman died in 2005, Paul A. Offit, MD, himself developer of a widely used rotavirus vaccine, filmed a series of interviews with Hilleman and other scientists. Now Dr. Offit has produced and released a documentary using the footage, and we are proud to host a screening of it. It's an excellent film, with fascinating historical footage, animations, and insights into the world of infectious diseases prevention. Please join us for the screening -- we think you'll really enjoy the film.

Posted in: General, Measles

September 30, 2016  Karie Youngdahl

The World Health Organization Region of the Americas has achieved a milestone in disease elimination – the Pan American Health Organization (PAHO) on September 27, 2016, declared the Americas to be free of endemic measles. In the pre-vaccine era, the WHO estimates that measles killed 2.6 million children per year globally, and so measles elimination has done a great deal to combat a major threat to child health. The Region of the Americas is the first of the six WHO regions to eliminate transmission of measles. The United States was certified measles-free in 2000, and the last cases of endemic measles were reported in other countries of the region in 2002. The International Expert Committee for Documenting and Verifying Measles, Rubella, and Congenital Rubella Syndrome Elimination in the Americas was responsible for collecting reports from region countries to certify that measles has in fact been eliminated. Polio (certification in 1994), rubella (2015) and smallpox (1971) have been eliminated from the region as well, and, of course, smallpox has been eradicated globally (certification in 1980).

Posted in: Measles, Public Health

September 27, 2016  Karie Youngdahl

Carley Roche, an intern here at The College of Physicians of Philadelphia, wrote today's blog post. In December 1924 the city of Philadelphia experienced an uptick in the incidence of smallpox with 9 new cases of the disease. While there had been a few reported cases earlier in the year, it soon became apparent in early January 1925 that the December outbreak might be more severe than the others, as the first smallpox death occurred in Philadelphia in more than 12 years. The Department of Public Health would spend the next 6 months quarantining and vaccinating citizens of the city in order to prevent a massive outbreak of smallpox beyond the city limits.

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August 31, 2016  Karie Youngdahl

Donald A. Henderson, MD, MPH, died on August 21, 2016, at age 87. Henderson was a crucial figure in the eradication of smallpox. Posted to the World Health Organization in 1966 as a CDC employee, he developed the program that would, just a little more than 10 years later, eradicate a disease that killed more than 30% of those it infected, and that was responsible for hundreds of millions of deaths in the 20th century alone. 

Henderson’s key insights into smallpox eradication came from his training by Alexander Langmuir as one of the early recruits of the CDC’s Epidemic Intelligence Service, as well as from his public health education at Johns Hopkins University School of Hygiene and Public Health. Though he launched the WHO’s program with the goal of using mass vaccination as the main tool to eradicate smallpox, his use of rigorous surveillance and reporting techniques, learned in these public health contexts, laid the groundwork for a shift in strategy that successfully employed containment, or ring, vaccination to halt the spread of outbreaks. 

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June 23, 2016  Karie Youngdahl

Three years of poor performance of the live nasal spray influenza vaccine (LAIV) have resulted in an unusual policy shift from the US Advisory Committee on Immunization Practices. At their annual meeting yesterday to discuss influenza vaccination recommendations, the ACIP voted that the LAIV should not be used in the 2016-2017 influenza season. Data released in May 2016 showed that the LAIV effectiveness was effectively zero as compared with about 60% for the inactivated vaccine, given via injection. According to the CDC, vaccine effectiveness is “the percent reduction in the frequency of influenza illness among vaccinated people compared to people not vaccinated.” No vaccine effectiveness was observed for the LAIV in children in 2013-14 nor in 2014-15. Based on these findings, last year the ACIP voted not to preferentially recommend the LAIV for young children over the inactivated vaccine. (The previous recommendations encouraged use of LAIV in children due to its assumed better performance at preventing disease.)

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June 21, 2016  Karie Youngdahl

I've been hosting an internal debate about whether to ignore the Del Bigtree/Andrew Wakefield documentary Vaxxed or to see it. On the one hand, the documentary is rehashing a false narrative about the MMR vaccine having a causal role in autism development that has been countered time and again with solid epidemiological evidence. On the other hand, I hate to dismiss something without investigating it more closely for myself. But up until now, the film hasn't been accessible to me and I could ignore it. That was no longer the case beginning this past weekend, when Vaxxed began showing for a few days at a local Philadelphia multiplex. In spite of my trepidation, and at the prodding of one of my colleagues, I went out yesterday to see it in the middle of the afternoon. This being downtown Philly, in the historic district, lots of tourists and museum visitors were walking near the theater. A mother and her two preteen kids were in front of me, across from the marquee prominently advertising that Vaxxed was playing. I heard her say to her kids, “Oh, I can’t believe Vaxxed is here – it’s this amazing movie that explains how the CDC is hiding evidence that vaccines cause autism.” The rest of her analysis trailed away as they made their way up Walnut Street.

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May 17, 2016  Karie Youngdahl

We know so little about Zika virus that we can’t even spell it correctly. Scott C. Weaver, MS, PhD, visiting Philadelphia from the University of Texas Medical Branch at Galveston, noted that the forest where Zika virus was discovered in the 1940s is actually spelled Ziika. Weaver brought years of research experience to his talk Monday, May 16, at The College of Physicians of Philadelphia. He is an arbovirus specialist and has worked extensively on Chikungunya virus, and, even before the current Western Hemisphere Zika virus epidemic, on Zika virus itself. Given that human cases of Zika virus disease were not known until the 1950s and that 80% of Zika cases present with no symptoms, it’s not surprising that we don’t know more about the virus and how it works. Before 2007, only 14 human cases had been diagnosed. Weaver traced the spread of Zika virus across the globe, showing a CDC map representing incidence of Zika virus antibodies and infection in local populations throughout many African and Asian countries. The virus almost certainly originated in Africa at least a millennium ago; about 50-100 years ago it spread to Asia. In 2007 the virus jumped to Yap Island from Asia, with a population of about 7,000 people, most of whom became infected. Then, in 2013, it moved to French Polynesia, with more than 100,000 people to potentially infect. French Polynesians then started to transport the virus around the world, probably to Brazil in late 2013. With this move to South America, hundreds of millions of people are now susceptible to infection. 

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