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Date: Dec 2015

This article was originally published on the Dengue Vaccine Initiative website and is cross-posted here with permission. IVAC is a member of the Dengue Vaccine Initiative (DVI). 

On December 9 2015, Mexico approved Sanofi Pasteur’s dengue vaccine marking the first time a dengue vaccine has been licensed for use in a country. Called Dengvaxia® and developed by the French pharmaceutical company, Sanofi Pasteur, the vaccine was approved for people aged 9 to 45 years in areas that are highly endemic, with a dengue seroprevalence of more than 60 percent.

The Dengue Vaccine Initiative (DVI) views Mexico’s licensure of Dengvaxia® as an important milestone in the fight against dengue. Recent studies have demonstrated that in children and adolescents aged 9 years and above, Dengvaxia® reduces dengue cases overall by approximately 65 percent; dengue cases requiring hospitalization by 81 percent; and severe dengue cases by 93 percent. The vaccine’s efficacy was most apparent in individuals with evidence of prior dengue virus exposure. In children below the age of 9 years and in those with no evidence of prior dengue, the vaccine’s efficacy was substantially lower. There was also an increased risk of cases requiring hospitalization during the third year after vaccine initiation in children under 9.

These results suggest that Dengvaxia® may have significant public health impact in reducing dengue disease burden for people 9 years of age and older, especially in areas with existing high infection rates of dengue. Questions remain regarding Dengvaxia®, including duration of protection, price, and impact on overall dengue virus transmission given that the youngest age groups will not be vaccinated. These and other issues will have to be closely followed in order to ascertain the ultimate impact of this vaccine.

Dengue, also known as “breakbone fever,” is caused by a virus transmitted by Aedes mosquitoes, the same mosquitoes that can transmit chikungunya and Zika virus. Dengue virus causes approximately 400 million infections globally each year. In the Americas alone, dengue’s economic burden has been estimated to cost $2.1 billion dollars a year.

DVI believes that this first vaccine licensure in a dengue-endemic country may pave the way for other countries considering new technologies to fight dengue, but stresses that the decision to introduce a dengue vaccine should follow scientific evidence. Following registration, ministries of health will still face important decisions about whether and how to introduce the vaccine into national programs. These decisions may vary according to the specific demographic characteristics, dengue epidemiology and the capacity of public health systems of each country. Therefore, DVI continues to strongly support increasing efforts to improve endemic countries’ access to the evidence needed to inform vaccine introduction decisions.

DVI also welcomes the decision by Mexico as an opportunity to increase our understanding of the questions raised above, as well as the effectiveness of the vaccine in field conditions. DVI recognizes the importance of effective integration of dengue prevention and control strategies, notably vaccination and vector-control approaches, to comprehensively reduce dengue. DVI also encourages the global health community to facilitate and support mechanisms for regional knowledge transfers and information sharing among endemic countries to collectively fight dengue and other vector-borne diseases that are also on the rise. We hope this development spurs other vaccine candidates currently in clinical development to continue to progress in the pipeline.

About the Dengue Vaccine Initiative
The Dengue Vaccine Initiative is an international consortium of the International Vaccine Institute, the World Health Organization Initiative for Vaccine Research, the International Vaccine Access Center at the Johns Hopkins University Bloomberg School of Public Health and the Sabin Vaccine Institute that specializes in research, health economics, policy and advocacy to equip countries with objective information and scientific evidence to fight dengue fever. The Initiative is supported by the Bill & Melinda Gates Foundation.

By Rose Weeks

This article was originally published on Next Billion and is cross-posted here with permission. 

FOUR REASONS TO STEP UP PROGRESS ON REDUCING DIARRHEAL DISEASE

When my 6-week-old son got his first rotavirus vaccine dose last year, my husband and I were up what seemed like all night as he fussed and spat up. But even in my sleep-deprived state, I felt relieved to know that he would be protected from this life-threatening diarrheal disease.

Before the rotavirus vaccine was introduced in 2006, hundreds of children died from diarrheal disease in the United States. It was a devastating and preventable loss of life, but a tiny fraction of the 600,000 children estimated to die globally from diarrheal disease annually.

The just-published Pneumonia & Diarrhea Progress Report states that countries with the largest number of deaths from these diseases have not yet fully scaled up the use of available solutions to prevent and treat diarrhea, like rotavirus vaccine, oral rehydration solution (ORS) and breastfeeding.

Diarrhea still kills 1,000 per day: “It’s better, but it’s still horrific,” said Dr. Richard Guerrant, the director of the University of Virginia’s Center for Global Health, at last month’s annual meeting of the American Society of Tropical Medicine & Hygiene, a convening of thousands of public health scientists.

Beyond the death toll, incidence has barely waned at all. Children in low- and middle-income countries continue to experience about three episodes of diarrhea each year. Repeated cases of severe diarrhea, especially during important development stages in a child’s life, can have a lasting impact on physical and cognitive growth. Diarrhea can also make children more susceptible to death from other causes like pneumonia.

THE UNFINISHED AGENDA


ORS only reaches 1 of 3 children in need.
Children sick with severe diarrhea can be fully rehydrated with ORS – an inexpensive mixture of sugar, salt and safe water – within a few hours. ORS has saved an estimated 50 million lives worldwide. However, only one-third of children in low- and middle-income countries who need ORS get it.

Dr. Christopher Duggan, a professor in the Harvard School of Public Health who has studied ORS since the 1980s, spoke at the TropMed annual meeting about how social marketing is a critical tool to expand access. In Bangladesh, Social Marketing Company, an offshoot of PSI, has invested millions in marketing the use of ORS. Today, Bangladesh’s coverage for ORS is 77 percent, the best of the high-burden countries. Bangladesh also packages zinc supplements – another proven way to reduce the duration and severity of diarrheal episodes – with ORS. As a result, the country has attained higher coverage of zinc use than any other country surveyed.

Even when not fatal, diarrheal infections stunt children’s growth and cognitive development.
Malnutrition weakens immune systems, making children more vulnerable to infections like diarrhea. Diarrhea, in turn, prevents children from absorbing nutrients, contributing to malnutrition. This creates a viscous cycle. Children with a typical number of diarrhea cases per year suffer an average of 8-centimeter growth loss and a 10-point IQ loss, said Guerrant.

Making the situation worse, many caregivers withhold food from children and babies when they are suffering from diarrhea. It is very important to continue feeding children appropriate food during an episode of diarrhea, said Duggan.

Innovative market-based approaches to improving nutrition include mobile clinics, training community health workers and door-to-door sales of Sprinkles (sachets containing micronutrients). Some m-health programs like Totohealth in Kenya use SMS to monitor child development.

Vaccines against rotavirus, which causes 2 in 5 diarrheal deaths, are not reaching more than 90 million children or 70 percent of all infants worldwide. And not all children in the U.S. are vaccinated.
Rotavirus causes 40 percent of diarrhea hospitalizations and 200,000 deaths in children younger than 5 each year. Unlike other forms of diarrhea, rotavirus infections cannot be controlled by hygiene and sanitation alone.

Two rotavirus vaccines have been internationally licensed since 2006 and are used routinely in nearly 80 countries. Despite this, only 15 percent of the children in countries eligible for vaccine support from Gavi, the Vaccine Alliance – the world’s poorest – have access to rotavirus vaccines.

Dr. Umesh Parashar, who leads the Centers for Disease Control and Prevention’s Enteric Viruses Epidemiology Team, said that the use of rotavirus vaccines in the U.S. has led to a striking decline in rotavirus-related hospitalizations. In some years, there are few cases observed. Yet, because coverage is still not routinely high, varying geographically from 59-88 percent, the accumulation of unvaccinated infants periodically leads to outbreaks.

Public health impact has been dramatic in low- and middle-income countries where rotavirus vaccines have been introduced. In Mexico, the vaccine led to a 50 percent decrease in diarrheal deaths in children younger than 5.

New rotavirus vaccines are being developed in emerging economies to expand supply and lower price, but may need more help to be available for other countries.
Dr. Duncan Steele of the Bill & Melinda Gates Foundation – now making headline-worthy investments in accelerating the introduction of rotavirus vaccine in low- and middle-income countries – discussed one bright spot on the horizon.

Companies in China, India, Indonesia and Vietnam are developing new vaccines with prices as low as U.S. $1 per dose for governments (such as Bharat Biotech’s ROTAVAC, which India is soon rolling out in four states). But there are not yet enough doses of these new vaccines to cover all children in the countries where they are being produced, much less the millions of children around the world who are in need of this vaccine.

THE TIME TO ACT IS NOW

“The main message is – we are not winning this fight,” Steele summarized, pointing to the need for greater advocacy to mobilize support for proven, low-cost diarrheal disease solutions such as ORS, zinc and dysentery treatment.

“The time to act is now,” urged Mathu Santosham, chair for the Rotavirus Organization of Technical Allies Council.

Fourteen of the 15 countries with the most deaths due to pneumonia and diarrhea are currently eligible for new vaccine support from Gavi, but five won’t be eligible for long and some have only months to seek funding for rotavirus vaccines. Most poor countries have yet to approach global targets for ORS and zinc use.

Regardless of their birthplace, all children should be protected from suffering, stunting and the risk of death from diarrheal disease.

Rose Weeks is the director of communications for the Center for American Indian Health at Johns Hopkins Bloomberg School of Public Health and secunded to the International Vaccine Access Center to support the ROTA Council project.