The Urgent Search for a Vaccine

The recent outbreak of the Zika virus in South America—which began in Brazil in May 2015 and has now spread to over 30 countries—has raised fears around the globe, as public health officials believe the viral infection threatens the health of both pregnant women and their unborn children.

The origin and current epicenter of the Zika outbreak is in Brazil. In November 2015, Brazil’s Ministry of Health announced a possible link between the increase in Zika infections and children born with microcephaly.

Although the limited data available on the Zika virus do not conclusively support this link, the correlation between these two observations, as well as additional circumstantial evidence including the possible detection of the Zika virus in the amniotic fluid of fetuses exhibiting signs of microcephaly, are forcing governments to assume that the Zika virus outbreak is directly connected to the spike in microcephaly cases. Furthermore, although most Zika virus infections are asymptomatic, the current lack of information on the long-term consequences of the infection—for example, a possible link between Zika and Guillain-Barré syndrome—is requiring governments to err on the side of caution. The recent announcement of the U.S. Centers for Disease Control and Prevention (CDC) that Zika might be also transmitted directly from person to person via sexual contact further underlines the need for immediate action. The WHO has estimated up to four million Zika cases might occur in the Americas within the next 12 months, clearly indicating that the Zika virus outbreak requires international attention.

Vector Control and Diagnostic Tools Desperately Needed

The preliminary goal in fighting the Zika virus will focus on the vector, well-known mosquito species that are also responsible for the transfer of the causative agents for malaria, dengue fever, yellow fever, and West Nile fever. Therefore, even in the unlikely scenario in which the Zika virus is not directly causing microcephaly in infants, local populations will still benefit from a reduced prevalence of the other pathogens transmitted by these mosquitoes. The immediate fight against A. aegypti and A. albopictus should be multifold and include the use of insecticides, the elimination of shallow standing water—particularly around densely populated areas—and the utilization of next-generation genetic (sterile male) or microbiological (Wolbachia, Chromobacterium [Csp P]) approaches to reduce the population of Zika vectors. GlobalData believes that in order to combat the virus more effectively in the short-term, the development of a reliable and cost-effective method to detect Zika infections is of paramount importance.

A Zika Virus Vaccine Will Not be a Silver Bullet Solution

A more ambitious, long-term goal in the fight against the Zika virus is the development of a vaccine that offers strong and durable protection against the virus. Importantly, although several companies—including pharma giants GlaxoSmithKline (GSK), Merck, Johnson & Johnson (J&J), Pfizer, and Sanofi—have already announced initial investigation into the possibility of developing a vaccine against the Zika virus, success will not come overnight. Even though the Zika virus has been sequenced, it is currently not clear what the best approach in developing a Zika virus vaccine will be, and a definitive timeline on vaccine development is impossible to ascertain.

Another consideration relevant to the creation of a Zika virus vaccine will be the future application of the vaccine. If the intent of governments is to use a possible Zika vaccine only during large outbreaks, the immunoprotection induced by the vaccine does not require a long-term effect. However, if a novel vaccine is eventually included in routine vaccination schedules, the requirements for prolonged protection, high seroconversion, and herd immunity would be important criteria for vaccine evaluations. As an alternative approach, a vaccine could be developed specifically to target pregnant women, possibly limited to specific geographic regions and seasonal applications, likely overlapping with areas that have elevated mosquito populations.

This could be a cost-effective alternative to other immunization approaches, although clinical trials targeting pregnant women may prove challenging as the safety and efficacy needs to be determined for both the mother and the unborn child. In addition, practical barriers might arise in less densely populated areas and in regions with limited access to healthcare, especially if the vaccine needs to be administered during the first trimester in order to prevent microcephaly. Hence, vaccine developers will face a variety of problems stemming both from uncertainty about future medical needs in preventing the spread of the Zika virus and from the lack of basic scientific data available for the Zika virus.

Global Collaboration is Required

Research will need to include direct evidence linking Zika infections with the microcephaly syndrome; the identification of all possible paths of viral transmission including direct transmission from person to person; the incidence rate of microcephaly in the case of an infection during pregnancy; other possible long-term symptoms caused by Zika infections; already-existing mutations within the ssRNA; mutation rates; and various other data, all of which will be required to effectively fight the Zika virus.

Brazil and its immediate neighbors are currently fighting a significant outbreak of the Zika virus, and GlobalData sees an opportunity for the international community to provide support for the countries experiencing the outbreak. This support can come in many forms since the successful fight against Zika will be based on a combination of governmental organization directly limiting its vectors; research institutions providing crucial data about the virus; diagnostic companies developing screens to identify infections in symptomatic and asymptomatic individuals; and pharmaceutical companies eventually providing vaccines. While this support will have an obviously positive impact in Brazil and the surrounding countries, it will also be of monumental assistance in limiting the future spread of the virus.

  • Mirco Junker

    Mirco Junker, PhD is Infectious Disease Analyst at GlobalData, Boston. Mirco Junker graduated from Notre Dame, conducted a postdoctoral fellowship at the Harvard Medical School, and now provides in-depth analyses of the healthcare industry by writing market research reports. 


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