The World Health Organization (WHO) has listed vaccine hesitancy—the delay in acceptance or refusal of vaccines despite their availability—as one of its top 10 health threats facing the world in 2019.
The phenomenon has taken hold in a number of countries around the world in recent times, and notably in the U.S. as well. Data from the Centers for Disease Control and Prevention shows that while coverage of most recommended vaccines remained relatively stable and high in 2017 for American children aged 19 to 35 months, the percentage who have received no vaccinations has quadrupled since 2001.
According to a recent study published in the journal PLOS ONE, increasing numbers of people in many U.S. states now hold anti-vaccination views.
"Since 2009, the number of 'philosophical-belief' vaccine non-medical exemptions has risen in 12 of the 18 states that currently allow this policy: Arkansas, Arizona, Idaho, Maine, Minnesota, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Texas, and Utah," the PLOS ONE study authors wrote in their paper.
Other countries with notable anti-vax movements include Australia, where around 40,000 children are unvaccinated because of the objections of their parents, and Italy, which introduced new rules in 2018 suspending the mandatory vaccinations that were required for children to be admitted to school.
According to the WHO, humanity has made significant strides in the past few decades when it comes to global health: Life expectancy has increased in many parts of the world, polio is on the verge of eradication and 6 million fewer children under the age of 5 died in 2016, compared with 1990.
But despite these achievements, significant global health problems remain, ranging from the prevalence of deadly noncommunicable diseases to the damaging effects of environmental pollution.
This year marks the beginning of the WHO's 13th General Programme—a five-year strategic plan with the goal of creating a healthier world for all by addressing the remaining challenges.
Below are 10 of the most significant issues that the WHO and its partners will tackle in 2019 (in no particular order.)
Air pollution and climate change
The WHO considers air pollution to be the greatest environmental risk to public health in 2019, not surprising given that nine out of 10 people breathe polluted air, leading to approximately 7 million premature deaths worldwide. Breathing in microscopic pollutants can lead to cancer, stroke and heart and lung disease.
Climate change is also expected to have a huge impact on people's health, with an additional 250,000 deaths expected annually between 2030 and 2050 due to the link between such conditions as malnutrition, malaria and heat stress.
Noncommunicable diseases are those that cannot be directly transmitted from one person to another, such as cancer, diabetes and heart disease. Collectively, they are the biggest killers of humans, responsible for 70 percent of all deaths worldwide. The most significant drivers of these diseases are high alcohol consumption, tobacco use, physical inactivity, poor diet and air pollution.
Global influenza pandemic
The WHO warns that a global influenza pandemic could strike at any time. As a result, the organization is collaborating with more than 150 institutions around the world to constantly monitor influenza strains. This will help to provide prevention and treatment strategies where outbreaks do occur.
Fragile and vulnerable settings
Crises—such as drought, famine, conflict and population displacement—and poor health services have left more than 1.6 billion people around the world, or 22 percent of the planet's population, without access to basic care.
Antimicrobial resistance—the ability of pathogens to resist treatment with once-effective drugs—is one of the biggest health challenges of our time. Increasing resistance means we may one day be unable to treat many infections, leading to a rise in illness, disability and death, without novel medical advances. Furthermore, it may mean that routine surgeries and chemotherapy could become extremely risky.
Ebola and other high-threat pathogens
Two outbreaks of Ebola in the Democratic Republic of Congo occurred last year, causing the deaths of nearly 400 people. This highlights the danger of known high-threat pathogens with the potential to cause epidemics—like Ebola, Zika, Middle East respiratory syndrome coronavirus (MERS-CoV) and severe acute respiratory syndrome (SARS)—as well as those that have yet to be discovered.
Weak primary health care
People in many countries around the world lack access to adequate primary health care services. This is a significant problem because they are the first point of contact that an individual has with a health care system. Often, service is of poor quality or is simply unaffordable.
Vaccines are an effective and affordable way to prevent the spread of many diseases. In fact, it is estimated that without them, there would be an additional 2 million to 3 million deaths every year. Despite this, a sizable minority of people in several countries around the globe refuse vaccines (for themselves or their children)—or hesitate to accept them—even when they are readily available, a phenomenon known collectively as "vaccine hesitancy."
This can make it a difficult task to achieve sufficient levels of coverage in a population, mitigating the effects of "herd immunity" and potentially leading to outbreaks of disease. For example, vaccine hesitancy has been identified as one potential factor contributing to the 30 percent increase in measles cases globally.
Every year, about 390 million people around the world are infected with dengue fever and about 40 percent of the global population lives in regions where it risks contracting the disease. Transmitted by mosquitoes, the flu-like fever has a mortality rate of below 1 percent when it is detected early and the patient receives medical care. However, this figure can rise significantly if the disease is left untreated.
While huge strides have been made in recent decades when it comes to preventing and treating HIV infections, millions of people are still dying of HIV/AIDS every year around the world. It is estimated that approximately 37 million people are currently living with HIV, with certain groups—such as sex workers, injecting drug users and men who have sex with men—are at particular risk of being infected.
This article was updated to include additional information on vaccine hesitancy.