Fighting the Zika virus - A lesson for defending against emerging pathogens

Dr. Gary J. Nabel, Chief Scientific Officer, Global Research & Development – Sanofi

In recent months, Zika virus has emerged as a global public health concern. Discovered in 1947 in Uganda, Zika infection previously posed no threat to humans because it was largely asymptotic: only one in five cases caused a mild self-limited illness, and outbreaks were confined to specific areas of Africa and Asia. However, in 2007, Zika began to spread across the Pacific to tropical and sub-tropical parts of the Americas.

As the virus disseminated to new geographic regions, physicians in affected areas reported a connection between infection and microcephaly, a birth defect where a baby’s head is smaller than expected when compared to babies of the same sex and age. It was also associated with Guillain-Barré syndrome, a disorder in which the body’s immune system attacks parts of the peripheral nervous system. Of additional concern was the recognition that infection could be transmitted by sexual contact, in addition to vector transmission by mosquitos. The sudden emergence of Zika in new areas and growing concern of its possible relationship with other devastating disorders has led global health experts to increase efforts to better understand the Zika virus and identify ways to combat its spread. 

The threat of Zika had prompted efforts to fight the outbreak. The biopharmaceutical industry has an important role to play in this response, together with partners in government/public health, academic and regulatory communities. To optimize use of resources and speed, focus must be prioritized strategically. In any emerging outbreak, the first priority is to accelerate the development of medicines already known to be safe in humans with known on-target efficacy. It is also useful to search for repurposed drugs that can be rapidly tested in clinical trials. The next priority is to advance vaccines and other antiviral therapies with efficacy to prevent and cure, respectively, Zika infection in relevant animal models. However, because the Zika infection is largely asymptomatic and self-limited in duration, treatment with antiviral drugs alone is likely impractical. For that reason, effective preventive measures, such as vaccines and antibodies, remain a priority.

Research companies with expertise in infectious diseases are working with global public health and regulatory agencies to accelerate the development of a vaccine to prevent the spread of this mosquito-borne illness. Biopharmaceutical researchers have begun to pursue several potentially promising avenues to address Zika. For example, the Zika virus is in the same family as several other mosquito-borne viruses, allowing scientists to draw important parallel insights that may inform drug development. One such insight includes the discovery that Zika shows a 60 percent genetic similarity with dengue viruses and some diagnostic tests and antibodies do not readily distinguish between the two. The development of a specific diagnostic assay at the point of care remains an urgent need for the field. At Sanofi, we are exploring whether a dengue vaccine named Dengvaxia could provide a platform for a Zika-specific vaccine to be developed or even protect against both viruses. Researchers are also exploring ways that antiviral treatments may be effective if used to complement vaccinations.

The emergence of Zika highlights the need for global action to defend against emerging pathogens. Sustained global investment and support from all stakeholders is needed to develop and test medicines that can be available in advance of outbreaks. In addition, diverse challenges exist to addressing diseases that occur in an outbreak setting. For example, the time window for determining safety and efficacy of novel vaccines and therapies in humans is limited, and the necessary population size and clinical trial infrastructure are lacking. Regulatory, manufacturing, legal and ethical considerations also add to the complexity. Only together, working in a collaborative approach, can the biopharmaceutical industry and partners solve the public health challenges posed by viruses like Zika and develop novel strategies for the development of future vaccines and treatments. 

Zika offers many lessons in global health preparedness – particularly because vector transmission, globalization and climate change have converged to increase the risks of further outbreaks. We have elsewhere proposed specific steps that might be taken to improve upon the current response, which is neither organized nor systematic ( G. J. Nabel and E Zerhouni, Sci. Trans. Med., 8;330d; 1-3 (a9) 2016). Our industry is committed to working with global health leaders to advance safe and effective vaccines to prevent the spread of Zika and to leverage the lessons from this and other outbreaks to learn how responses can be improved. Agile and effective collaboration can save lives around the world.

For more information go to: http://phrma.org/zika-virus-backgrounder