Is there a silver lining to the Zika virus epidemic in the Americas?

It is hard to find anything positive to say about an epidemic of an emerging virus that infects pregnant women, targets developing fetuses’ neural progenitor cells, and disrupts the sequence of neural development to cause a devastating syndrome resulting in lifelong disabilities. Microcephalic infants became the faces of the American Zika epidemic, which affected almost all countries in the Western Hemisphere in 2014–2017. Recently, Zika has nearly disappeared from the Americas as quickly as it emerged. Now that the dust is settling, what have the scientific and public health communities learned? Is there a silver lining to Zika’s devastation?

The American Zika epidemic mobilized scientists throughout the region and beyond with a force reminiscent of the response to the emergence of HIV. As emerging infections do not follow the same pace as research funding agencies, many scientists, staff, and students worked without pay early in the epidemic, as they understood the urgency of their work. They were passionate to uncover the fundamental rules of Zika—modes of transmission, accurate diagnosis, spectrum of clinical manifestations, and methods of prevention and treatment. To uncover these rules, scientific teams crossed disciplines—in our case, a virologist, perinatologist, child psychologist, immunologist, and infectious disease specialist often shared calls across countries and time zones. These multi-disciplinary research teams endure and will tackle other high burden diseases in the future.

To address the problem of diagnosis of the closely-related Zika and dengue viruses, these teams raced to develop novel recombinant antigens and monoclonal antibodies to differentiate the two infections.^1–3 Another major advance came in the use and adaptation of child development assessment tools. In many low- and middle-income countries (LMICs), these assessment tools are not in routine use and are not widely available. The response to the Zika epidemic resulted in an increasing number of child behavior specialists who became skilled in performing these assessments for research. Not surprisingly, with all of these efforts, the number of Zika-related publications in PubMed rose from just three in all of 2013 to an average of 177 publications per month in 2019. We now know the ways in which Zika can be transmitted, have improved diagnostics, better understand the full spectrum of clinical disease, and have made major advances in the development of Zika vaccine candidates. In carrying out their work, these North-South and South-South collaborations undoubtedly strengthened research and laboratory capacity in the region.

Similarly, the public health communities in countries affected by Zika mobilized in response to the epidemic. These institutions strengthened surveillance for birth defects and devised new approaches to surveillance of emerging infections in pregnant populations.⁴ In most cases, these communities became aware that services for affected children were inadequate. To address the lack of access to child behavioral specialists in LMICs, UNICEF and others are now implementing early childhood interventions to support the development of children, including those without Zika.⁵ The Zika epidemic added momentum to this “imperative for action and measurement at scale” for at-risk children in LMICs. There are also efforts to educate healthcare providers on the evaluation of child development and to provide guidance about early stimulation. Many interventions consider the realities of the local context in LMICs and can be carried out by the child’s caregivers. Even simple interventions, when introduced early in a child’s life, have been shown to generate life-long gains.⁶ However, these interventions will need to be longitudinal: delayed neurodevelopment, most notably in language, was recently reported in toddlers exposed to Zika in utero.⁷ This was also an important lesson learned from the HIV epidemic, that children and families affected by Zika need a lifetime of psycho-social support and behavioral interventions to complement their medical care.⁸ For families affected by Zika, a difficult road still lies ahead, and we must continue to provide necessary support services even though the initial urgency of the outbreak has passed.

Whether or not we experience future Zika epidemics, we will certainly see the emergence of new pathogens with unanticipated consequences. In applying the lessons of Zika to the next epidemic, we should rapidly deploy research funding and prioritize ethical reviews of emerging infection research. We should work to continue to strengthen surveillance systems, and be ready to integrate efforts to prevent transmission with maternal, reproductive, and pediatric health services.⁹ For Zika specifically, a silver lining is that we now understand its fundamental rules, and can confront the next epidemic armed with this knowledge.