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History of Vaccines Blog

September 28, 2017  Karie Youngdahl

The World Health Organization has reached another disease elimination milestone: the organization announced on September 21, 2017, that maternal and neonatal tetanus have been eliminated from the WHO Region of the Americas. This achievement comes after a concerted campaign in Haiti to prevent the disease through intensive immunization campaigns, improved surveillance, and attention to safe birth and umbilical care practices. Tetanus is a serious infection with particularly high case-fatality rates in neonates, who may contract the disease via unhygienic birth practices and through improper handling of the umbilical cord and stump. Tetanus has an unusual elimination threshold – unlike other disease that have been eradicated (smallpox) or eliminated regionally (polio, rubella, and measles in the Americas for example), tetanus is not passed person-to-person.

Posted in: Public Health, Tetanus

July 11, 2017  Karie Youngdahl

A year of measles outbreaks in Europe have led to 35 deaths and more than 12,000 confirmed cases. Thirty-one of the measles deaths have occurred in Romania, where years of declining measles-containing vaccine (MCV) coverage is taking its toll. For 2015, the World Health Organization estimates two-dose MCV coverages at 88% of Romanian children, down from a high of 97% coverage in 2003. Measles remains endemic in 14 European countries. In most countries experiencing outbreaks this year, measles immunization rates are much lower than the 95% coverage needed to support herd immunity.Italy alone has recorded 3,300 confirmed cases of measles and one death this year to date – the last time the US, obviously a much larger country, recorded more cases was in 1991, the year of a major epidemic.

Posted in: Measles, Public Health

April 24, 2017  Karie Youngdahl
By 2017, will polio be eradicated? Will we have a new Lyme disease vaccine? Can we make influenza vaccines more effective? Vaccinologist Stanley A. Plotkin, MD, made a series of predictions for the field for the next ten years that included some hopeful answers to these questions, along with a more pessimistic take on the effect of the current political climate on vaccine acceptance and support for scientific research. Plotkin made his predictions at the National Foundation for Infectious Diseases Annual Conference on Vaccine Research in Bethesda, Maryland. But first, he reviewed his predictions from the 2007 conference when he completed a similar exercise.
Some of his 2007 predictions have come to pass: a new monovalent rotavirus vaccine was licensed, the rotavirus disease burden in developed countries that use the vaccine has been greatly reduced, and the HIV vaccine tested in the Thai trial showed partial efficacy. However, his prediction did not come to pass that by 2017 a prophylactic Type 1 diabetes vaccine for those at high genetic risk of the disease would be licensed.
Posted in: General, HIV, Influenza, Pertussis (whooping cough), Pneumococcal disease, Polio, Public Health, Rotavirus, Vaccine Research

February 21, 2017  Karie Youngdahl

Are you a glass half empty or glass half full type of person? Your orientation along the optimism-pessimism spectrum will determine whether you think this year’s seasonal influenza vaccine is a moderate success or near failure. The Centers for Disease Control and Prevention released its interim estimate of the 2016-17 influenza vaccine effectiveness (VE) last week: the vaccine appears to be 48% effective at preventing physician-attended influenza illness.This VE estimate is similar to last year’s estimate of 47% VE. You can see a table of VE for 2004-16 here. How does the CDC get these data? CDC used five study sites, where they enrolled patients aged ≥6 months seeking outpatient medical care for an acute respiratory illness (ARI) with cough, within 7 days of illness onset. Researchers interviewed study subjects or their parents to collect respiratory specimens, demographic data, health status, symptoms, and 2016–17 influenza vaccination status. Specimens were tested at U.S. Flu Vaccine Effectiveness Network laboratories using CDC’s real-time reverse transcription – polymerase chain reaction (rRT-PCR) protocol for detection and identification of influenza viruses.

Posted in: Influenza, Public Health

January 11, 2017  Karie Youngdahl

Robert F. Kennedy Jr.'s announcement yesterday that president-elect Donald J. Trump asked him to chair a government commission on "vaccine safety and scientific integrity" has prompted a deluge of responses on social media, on blogs, and in the media in general. Though he calls himself (and Trump) "very pro-vaccine," Kennedy has been a dogged pursuer of the discredited connection between vaccination and autism and other neurodevelopmental disorders. If Kennedy's statement about his appointment is true -- and a Trump spokesperson has not quite confirmed it -- public health and medical workers are right to be concerned about the effect this commission may have on public perception of vaccines. 

Posted in: General, Public Health

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

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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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