Vaccination in 2019: Daunting Challenges and Optimism

The Closing Plenary of IDWeek 2019 led the audience on a journey from the daunting challenges of vaccination that are the reality in 2019 to the optimism that at least some global infectious diseases may be eradicated within the next few generations.

Remarkable progress has been made in reducing the death of children under 5 years of age to a number of infectious. The global cases of measles and tetanus have dropped by over 80%, with diphtheria reduced by over 70%, according to Peter Hotez, MD, PhD, Baylor College of Medicine, Houston, Texas. However, this good news does not extend to a raft of “neglected tropical diseases,” which affect about 1.6 billion people and include schistosomiasis, leishmaniasis, and Chagas disease.

Efforts by Hotez and others to both reduce the costs of vaccination and expand vaccination efforts, have made inroads into reducing the number of cases. The not so good news is the changing drivers of disease in the 21^st century. “New global Anthropocene hot zones of neglected tropical disease and disease for which vaccines exist have arisen in regions of the world as a result of political instability combined with climate change, urbanization, deforestation, shifting poverty where poor are increasingly living amidst the wealthy, as well as antiscience,” said Hotez.

This dismal reality includes Texas and the Gulf Coast. The region is 1 of the hot zones where poverty, climate changes that favors the establishment of organisms like the Zika virus, and urbanization have combined to fuel emergence of diseases.

Antiscience in the form of “vaccine hesitancy” has become a prominent driver. In Texas, for example, non-medical vaccine exemptions have risen from a couple thousand in 2003 to over 63,000 in 2018. Media saturation of false information, “well-oiled” political lobbying, and specific targeting of pediatric infections have fueled the antiscience, antivax sentiment.

Long an antiscience critic, Hotez has become the target of antivax fury. He is undeterred, citing various global programs that continue to pursue expanded vaccination and research in hard-hit regions, and campaigns to counter the spread of disinformation that give cause for hope.

One beacon of hope is Anthony Fauci, MD, Director of the National Institute of Allergy and Infectious Diseases (NIAID) in Bethesda, Maryland. Within his tenure as NIAID director, the global picture of emerging/re-emerging infectious disease has gone from 1 (HIV) to dozens.

Fauci spoke of a changing landscape of infectious diseases that has spawned a “3-pronged” 21^st-century approach that hinges on 3 approaches.

The first is the priority-pathogen approach. The wake-up call for this thinking came in the wake of the World Trade Center catastrophe, with the deliberate dissemination of anthrax. The development of vaccines for smallpox and anthrax reflect this view. The priority approach also encompasses threats that emerge naturally and spread. These include Ebola, Lassa fever, Nipah virus infection, Zika, and severe acquired respiratory syndrome (SARS).

The second is the platform approach, which harnesses platform technologies, such as DNA and RNA vaccines, viral vectors, recombinant proteins, nanoparticles, virus-like particles, and adjuvants, to battle infections.

Finally, the prototype pathogen approach uses the wisdom of past experience to devise prototype vaccines. Knowledge of the relatedness of a virus to other pathogenic viruses can guide research that seeks viral targets that offer the best opportunity for vaccine success. As one example, development of the SARS vaccine took 20 months. Flash ahead a decade and the process for the Zika virus took only 3.25 months. Optimism is growing that the use of nanoparticle-based vaccine technology could produce a vaccine that is not blunted by genetic drift that can occur during the current process, and which might yield a universal vaccine.

An intriguing strategy that is being pursued assumes that broadly neutralizing antibodies that are induced by a vaccine are the basis of the protection. These antibodies are being used to trace back to the epitopes (immunogens) on the virus or bacterium that are the disease culprits. The vaccine would stimulate antibodies to the immunogens, allowing precisely targeted protection.

“Twenty-first century vaccinology is combining the traditional 3-pillar priority pathogen, platform technology, and prototype pathogen approach with structure-based immunogen design,” said Fauci.

The optimistic tone was continued by the final speaker, Penny Heaton, MD, chief executive officer of the Bill & Melinda Gate Medical Research Institute in Cambridge, Massachusetts. Protection from infectious diseases has been breathtakingly successful in the United States in the past 3 decades for diarrheal disease, pneumonia, and polio, as examples. But the success has eluded poor regions of the globe. The raison d’etre of the institute is the premise that freedom from infectious disease are for all, not just for those who can afford it.

The poorest among us are susceptible to tuberculosis, malaria, and diarrheal diseases, with a collective death toll of about 2.5 million each year. Diarrheal diseases are the leading cause of death among children under 5 years of age in sub-Saharan Africa. “This should not be. This does not have to be,” said Heaton.

The Bill & Melinda Gate Medical Research Institute funds various steps from basic research to phase 3 testing of vaccines. “Our mission is to help develop products to accelerate the end of the tuberculosis epidemic, eradicate malaria, end diarrheal deaths in children, and reduce adverse birth outcomes and mortality due to infectious diseases,” explained Heaton.

One example is the development of a means of vaccination against measles and rubella using a patch that is applied to the skin for a short time. Research is in infancy stages. If successful, vaccination could be delivered in rural populations cheaply and without the need of medical personnel and dedicated vaccine storage technology. Once developed, the patch vaccination technology could be expanded to other diseases.

These and other initiatives keep Heaton optimistic that what has been experienced in the United States in the past several generations can become a global success.

DISCLOSURES

Anthony Fauci: none

Penny Heaton: none

Peter Hotez: none

PRESENTATIONS

SUNDAY OCTOBER 6 Closing Plenary Session

All About Vaccines: The Individual, the Community, the World

Peter Hotez MD, PhD, founding dean of the National School of Tropical Medicine, Baylor College of Medicine, Houston, Texas: Neglected Disease and Vaccine Diplomacy in a Time of War, Political Instability, Antiscience, and Climate Change

Anthony S. Fauci, MD, director of the National Institute of Allergy and Infectious Diseases

Bethesda, MD: Vaccines for Emerging Infectious Disease Threats: From Science to Implementation

Penny M. Heaton, MD, CEO, Bill & Melinda Gates Medical Research Institute

Cambridge, MA: Developing Vaccines for Poverty-Related Diseases: A New Global Public Health Model

Brian Hoyle, PhD, is a medical and science writer and editor from Halifax, Nova Scotia, Canada. He has been a full-time freelance writer/editor for over 15 years. Prior to that, he was a research microbiologist and lab manager of a provincial government water testing lab. He can be reached at hoyle@square-rainbow.com