Editor's Note: Henrietta H Fore is the executive director of UNICEF. Tedros Adhanom Ghebreyesus is the director general of the World Health Organization. The views expressed in this commentary are their own. View more opinion on CNN.
(CNN) - We are in the middle of a global measles crisis. Cases have soared across the world, including in places where measles had previously been eliminated -- like the United States. In this year to date, the United States has already seen its second-greatest number of cases since 2000. And this past week, New York City declared a public health emergency due to the rapid spread of the virus.
Behind each of these outbreaks, an alarming picture unfurls. In just the first three months of 2019, there have been more than 110,000 measles cases reported worldwide, a figure that is up nearly 300% from the same period last year. And these numbers will represent just a fraction of all the cases that occur. By the time you finish reading this, we estimate that at least 40 people -- most of them children -- will be infected by this fast-moving, life-threatening disease.
We're worried not only because measles can be so severe -- it still causes over 100,000 deaths every year -- but also because it is extremely contagious.
In those who are not immune, measles will infect approximately 9 in 10 people exposed to it. And since it is so infectious, it may be the first disease to appear where children are not getting the vaccines they need to keep them safe. And the presence of measles can point to a pocket of unvaccinated children and a possible dysfunction in the health system.
In short, measles is the canary in the coalmine of vaccine preventable illnesses.
And the risks are high. Around the world, millions of children are still missing out on lifesaving vaccines, leaving them and their communities vulnerable to disease and deadly outbreaks. Largely, this is a problem of access. Most live in countries where weak health care, poverty and conflict greatly undermine children's chances of getting vaccines.
But while parents in many countries are clamoring for vaccines, public uncertainty about the necessity and safety of vaccination threatens gains elsewhere.
In several high- and middle-income countries, from the United States to Ukraine, from France to the Philippines, there are parents who are delaying or refusing to vaccinate their children because they're unsure of the need for vaccines or that vaccines are safe.
This uncertainty can be fueled by the proliferation of confusing and contradictory information online. Dishonesty and distortions about vaccines are nothing new. But in today's digital age, myths can spread as fast and far as a computer virus.
In Brazil, for example, at the height of a yellow fever outbreak last year, misinformation about the safety of the vaccine circulated so quickly online that it hindered the ability of responders to bring the outbreak under control.
Harmful content has proliferated on digital channels, amplified by algorithms that reward controversy and clicks, and exploited by anti-vaccine activists to sow mistrust. Scientists, medics and health advocates have even been harassed for sharing factual health information. In addition, unproven vaccine "alternatives" are being heavily marketed for financial gain and entirely unscientific studies virally reproduced -- often within echo chambers, created by closed groups and selective news feeds, where they are difficult to refute.
It is understandable, in such a climate, how loving parents can feel lost. The answer is not to demonize or shame them, as they search for the truth about how to keep their children safe and healthy. It is a collective responsibility to support parents and build a more positive environment for vaccination -- on and offline.
We welcome initial steps taken by digital companies such as Facebook, Amazon and YouTube to quarantine these vaccine myths, but it will take much more -- not only from these online platforms but from governments, individuals and the health community -- to make sure all children get their vaccines at the right time.
It will mean empowering all health workers to be champions for vaccination, so that they can engage effectively with the parents and communities they serve.
It requires each of us to stand up for science, for health and for the importance of vaccines. It means building basic scientific literacy -- ensuring people can interpret and understand information about their health and vaccines.
It means governments must invest in primary care and immunization, and make sure these services are affordable, accessible and truly responsive to parents' needs -- especially those in the poorest, most disadvantaged communities.
To do our part, the World Health Organization and UNICEF, along with other partners of the Gavi, the Vaccine Alliance, are working to ensure that vaccines reach more people in more countries than ever before. We are supporting national authorities to strengthen health systems and services, respond to outbreaks and build trust.
Ultimately, there is no "debate" to be had about the profound benefits of vaccines. We know they are safe, and we know they work. More than 20 million lives have been saved through measles vaccination since the year 2000 alone.
But children are paying the price for complacency. It will take long-term efforts, political commitment and continuous investment -- in vaccine access, in service quality and in trust -- to ensure we are, and remain, protected together.