Breakthroughs Blog: Vaccines

In this regular feature on Breakthroughs, we highlight some of the most interesting reads in global health research from the past week. Scientists at the National Institutes of Health’s National Institute of Allergy and Infectious Diseases have developed a Zika transmission model using mice in order to model the virus’ transmission from human-to-human. While humans are naturally more susceptible to contracting Zika than mice are, scientists were able to use genetically modified mice to validly mimic the transmission. Scientists found that while vertical transmission is possible from mother to fetus, some of the fetuses were not infected with the disease, suggesting the placenta is capable of being an effective barrier to the disease. They also found that Zika can be found in the lymph nodes, suggesting the virus can infect more areas of the body than previously thought. The World Health Organization has provisionally recommended the use of a new insecticide bed net, the Interceptor G2, which is capable of killing up to 75 percent of mosquitos that have become resistant to a common insecticide. The Interceptor G2 bed net combines two different insecticides: pyrethroid, which is currently used in insecticide-treated nets, and chlorfenapyr, an insecticide previously only used in agricultural settings. Studies in sub-Saharan Africa have yielded promising outcomes, with the nets remaining effective even after having been washing up to 20 times. Three studies recently published in Emerging Infectious Diseases found new treatments against multidrug resistant (MDR) and extensively drug resistant (XDR) tuberculosis (TB) are delivering positive results. The largest study focused on a year-long delamanid treatment for 53 MDR-TB patients. Following treatment, 73.6 percent had a favorable response, with 67.6 percent of participants having multiple negative TB cultures. The second study analyzed bedaquiline therapy on 27 children with both MDR- and XDR-TB, and found that of the 23 children that remained a part of the study over the year, all had negative cultures. The third study was retroactive, with researchers observing combined bedaquiline and delamanid therapies in XDR-TB patients. In a total of five participants, researchers found one was culture negative, three were continuing treatment, and one had died. While these studies all have small sample sizes, preliminary data suggests these drugs have a high efficacy in treating resistant strains of TB.

In this regular feature on Breakthroughs, we highlight some of the most interesting reads in global health research from the past week. The World Health Organization (WHO) and UNICEF have reported nearly 1 in 10 children did not receive any immunizations in 2016. This includes immunizations for diphtheria-tetanus-pertussis (DTP). WHO and UNICEF reported that the global immunization rate for the full round of the DTP vaccine is only 86 percent, falling short of the 90 percent goal of global immunization. Furthermore, in 2016, eight countries had DTP immunization rates of less than 50 percent. Estimates by WHO and UNICEF suggest that 10 million more children in 64 countries need to be vaccinated every year in order to achieve the 90 percent goal. This highlights the need to bring vaccines to low-resource settings that have been chronically affected by low immunization rates. A new study published in Proceedings of the National Academy of Sciences highlights a new diagnostic tool that performed well in distinguishing Zika from other flaviviruses, including dengue. UC Berkeley and Humabs BioMed partnered to create a low-cost, easy-to-use diagnostic tool to specifically test for the Zika virus. Researchers found this tool was capable of distinguishing between Zika and other flaviviruses, as well as distinguishing current and past Zika infections in patients. The tool had 91.8 percent sensitivity—the ability to correctly identify those with the disease—and 95.9 percent specificity—the ability to correctly identify those without the disease. This tool could be used in Zika- and dengue-endemic areas, assisting in diagnostic processes and subsequent treatment, especially among populations adversely affected by Zika, like pregnant women. For the first time in history, more than half of all HIV-infected individuals are receiving treatment. In 2016, it was estimated that 19.5 million individuals were receiving HIV treatment, with a total of 36.7 million people infected with HIV. These estimates are both increases from the estimated 17.1 million treated and 36.1 infected in 2015. Further, AIDS-related deaths have decreased by more than half since 2005. Though these rates are promising in the fight against the global epidemic, the United Nations (UN) acknowledges that there is much left to do in the fight against HIV and AIDS, particularly in the context of less stable health systems in resource poor settings.  

In this regular feature on Breakthroughs, we highlight some of the most interesting reads in global health research from the past week. In response to a 2004 meningitis B epidemic in New Zealand, health clinics across the country offered free vaccinations over the course of two years for any individual under the age of 20. The vaccine, MeNZB, is used primarily to protect against meningitis B, but according to ecological data in Cuba, New Zealand, and Norway, the vaccine also appears to be associated with reduced rates of gonorrhea. To study this further, researchers took retrospective data from 11 health clinics across New Zealand, and compared rates of gonorrhea and chlamydia, analyzing the relationship between vaccination and infection rates. The researchers found that vaccinated individuals were significantly less likely to contract gonorrhea than their unvaccinated counterparts—but vaccine effectiveness rates fell for those co-infected with chlamydia. While this vaccine was only on the market from 2004–2006, these results suggest further study of the vaccine’s potential is warranted, especially as gonorrhea becomes increasingly resistant to first-line drugs. The path toward the elimination of measles, mumps, and rubella has been stymied by low vaccination rates in certain areas of the world, including in developed countries like Italy, Romania, Germany, and the United States. The surge in incidence and deaths from these diseases in developed areas of the world suggests there are pockets of low-immunized communities that are leaving thousands of neighboring children in danger of contracting these diseases. The debunked belief that vaccines cause autism has also contributed to this decline in immunization rates. The recent Ebola outbreak in the Democratic Republic of the Congo (DRC) helped the global health community understand the many complex, moving parts to contain an outbreak. While the DRC beat this particular outbreak in a short period of time, the global health community is still worried that this was merely an exception and the international community is still not equipped with the systems needed to deal with a complex, intercontinental pandemic. The outbreak happened in an incredibly remote area of the DRC, which limited the spread of the virus. While the response by the government and the World Health Organization was quick and effective, it is important to consider that outbreaks that occur in or closer to larger towns could pose a much greater threat and complicate the response. Another important factor in managing an outbreak like Ebola is the political health of a nation. Countries like Sierra Leone and Liberia, both heavily impacted by the 2014 outbreak, have been institutionally weakened by recent civil wars, leaving them more susceptible to large-scale and more deadly outbreaks.  

In this regular feature on Breakthroughs, we highlight some of the most interesting reads in global health research from the past week. While polio has continued on a path toward global eradication, there have still been many substantial obstacles. The most recent challenge has been the number of cases of polio reported due to the oral polio vaccine. The vaccine, containing a weakened form of the live virus, caused just over 20 cases of polio in 2017—more than the to-date cases of wild polio. Polio is considered a “smart” virus with the capability of mutating and regaining strength rapidly, causing more problems for areas of the world that rely on the live, oral polio vaccine. Even with the problems surrounding the live polio vaccine, the vaccine has saved hundreds of thousands of lives and is credited with driving down infection rates to near-zero. Once the majority of the population is vaccinated and cases of all polio infections level off, public health professionals can begin to taper off using the vaccine to ensure continued eradication. Pandemics are among the most likely uninsured risks to occur, risk modelers have argued. A moderately severe pandemic event could cost upward of US$750 billion and affect tens of countries across the globe. To combat this financial risk, the World Health Organization (WHO) launched a pandemic bond program to prevent this risk. The bond program—called the Pandemic Emergency Financing Facility (PEFT)—would provide substantial funds to any country affected by a pandemic, and the turnover of the funds would be quick. If a program like PEFT existed during the 2014 Ebola pandemic, millions of dollars and thousandsof lives could have been saved. Instead, countries like Liberia and Sierra Leone struggled to come up with the funds to cover the various expenses associated with pandemics. Investors are already keen on buying into the bond program, suggesting it will be successful in the long-term effort to curb the disastrous effects of a moderately severe pandemic.  A generic version of a popular HIV antiretroviral drug recently launched in Kenya, making it the first country to debut an affordable HIV treatment. The drug launch is a part of a larger Optimal ARV Project, with the goal to increase access to treatment in areas of the world affected by HIV and AIDS, malaria, and tuberculosis. The antiretroviral is one that is most commonly used around the world, including the United States, with quick, positive results and minimal side-effects. While the daily regimen of taking antiretroviral drugs is still a tedious and essential set of tasks, the generic version offers poor individuals in remote-access areas the ability to use the drug with increased frequency, achieving better results, and driving down incidences of HIV.