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History of Vaccines Blog


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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May 12, 2016   Karie Youngdahl

The College of Physicians of Philadelphia is pleased to announce a public program on Monday, May 16, 2016, at 8 am (breakfast at 7:30am) on the Zika virus epidemic. Scott C. Weaver, PhD, of the Institute for Human Infections and Immunity at the Galveston (Texas) National Laboratory, and Professor, Departments of Pathology and Microbiology & Immunology at the University of Texas Medical Branch at Galveston, will speak about current efforts toward understanding Zika virus pathophysiology and epidemiology and building an effective Zika virus vaccine. Paul A. Offit, MD, vaccine developer and chief of infectious diseases of the Children’s Hospital of Philadelphia, will comment.

Posted in: General

April 20, 2016   Karie Youngdahl

At Tuesday’s sessions of the National Foundation for Infectious Diseases Annual Conference on Vaccine Research, vaccine scientists were moderately hopeful about developing an effective Zika virus vaccine. Their hope stems both from precedent and from the relatively simplicity of Zika virus: several effective vaccines for related flaviviruses have been developed, and there appears to be only one serotype of Zika virus, unlike, for example, dengue virus, which has four types. Colonel Paul B. Keiser, MD, Walter Reed Army Institute of Research, described the other flavivirus vaccines and the lessons they offer for Zika. Yellow fever vaccine has been used since the 1930s and is exceptionally effective, although it does present serious risks to certain individuals. An inactivated vaccine for tick borne encephalitis has been available in Europe since the 1970s. This vaccine doesn’t have the effectiveness profile of yellow fever vaccine and must be given in a three-dose series with boosters every 3-5 years. The Japanese encephalitis vaccine is another model for Zika vaccine: it is formalin inactivated and given generally in a three-dose series

Posted in: General, Public Health, Yellow Fever

April 18, 2016   Karie Youngdahl

At the National Foundation for Infectious Diseases Annual Conference on Vaccine Research, presenters drew pointed comparisons between the 2014-15 Ebola epidemic and the current Zika virus disease epidemic. A session on multi-sector global efforts to test an Ebola virus disease vaccine (EVD) brought together representatives from the US Centers for Disease Control and Prevention (CDC), the World Health Organization (WHO), and the Norwegian Institute of Public Health. Anne Schuchat, MD, Principal Deputy Director of the CDC, prefaced her talk by noting that the West African EVD epidemic was the largest outbreak CDC has been involved in and involved ten times as many cases as all previously known EVD outbreaks combined. So, she says, we learned a great deal about the disease that we hadn’t known before, such as the persistence of Ebola virus in body fluids long after initial infection.

Posted in: General, Public Health

March 25, 2016   Karie Youngdahl

The World Health Organization is reporting a yellow fever outbreak in Angola that began in late 2015. Since the last reported yellow fever cases in Angola occurred more than 30 years ago, this epidemic, with more than 450 cases and 178 deaths, is alarming. The yellow fever virus is carried by mosquitoes, which infect humans with the virus as the female insects feed on blood. In Africa, 34 other countries are subject to yellow fever, but case counts have been declining in recent years. Yellow fever vaccination is part of the routine infant immunization schedule in most countries at risk for the disease. However, yellow fever immunization coverage is nowhere near universal: in Angola, it has ranged from a low of 37% of eligible infants covered in 1997 to 49% in 2013 and 77% in 2014.

Posted in: Yellow Fever

March 16, 2016   Karie Youngdahl

Today's blog post is by Carley Roche, a recent graduate from Drexel University and an intern here at The College of Physicians of Philadelphia. War is difficult on everyone, from the soldiers risking their lives to the civilians who get caught up in these violent affairs. While larger armies and more advanced weapons can aid in victory, an often overlooked variable in war chooses no allegiance: disease. One of the most devastating diseases throughout history during wartime has been typhus. Typhus is a bacterial disease caused by Rickettsia bacteria. There are two types of the disease--endemic typhus and epidemic typhus. Rickettsia typhi causes endemic typhus, also known as murine typhus, and is the least virulent. Spread to humans by fleas on animals such as cats, opossums, raccoons, and rats, most notably from the Norway rat, victims of endemic typhus will experience a bodily rash, high fever, nausea, vomiting, discomfort, and diarrhea. Rickettsia prowazekii causes epidemic typhus, which is spread via lice. Symptoms are similar to endemic typhus; they are, however, much more severe and can include delirium, hypotension, and even death.

Posted in: General