These recommendations represent the collective effort of working group members. They reflect a consensus opinion, acknowledging that individual participants had differing views on some issues. The issues addressed here are complex and cover a wide range of potential gene drive technologies. Therefore, these recommendations will need to be interpreted in a case-by-case manner depending on the nature of the investigational gene drive products and the environment where they are to be tested. The working group members agree that these recommendations provide important context and direction for further planning.
The term “threshold” refers to the proportion of modified mosquitoes with respect to the total mosquito population that will reliably initiate spread of the modification to high levels within the local mosquito population by mating. The goal of gene drive is to rapidly increase the proportion of vector mosquitoes carrying the beneficial modification. Low-threshold gene drives are defined here to include those that are predicted to spread from a rare introduction (zero threshold) or low initial release frequency.
Population suppression is sometimes called population reduction. Population replacement is sometimes termed population modification, population alteration, population transformation, or population conversion. The present article retains the terminology that was used in the WHO Guidance Framework.
The working group acknowledged that self-limiting or self-exhausting drive approaches might be useful in restricted locations, for other diseases or under other transmission conditions, and recognized the importance of modeling for making this determination.
It is possible that candidates may be imported in the form of a modified mosquito strain, most likely as eggs, to be interbred with local mosquitoes or as a DNA construct to be introduced into local mosquitoes by transfection.
This phase of testing is herein termed physical confinement, in keeping with the terminology of the WHO Guidance Framework,14 but is also widely known as containment. Recommendations are based on requirements recognized as Arthropod Containment Level (ACL), and the physical structure is standardly called a containment facility.
We thank the following for reviewing this report and providing valuable comments and suggestions: Jérémy Bouyer, Brinda Dass, Jason Delborne, Kevin Esvelt, Sarah Hartley, Calestous Juma, Daniel Masiga, Alan Pearson, Kent Redford, and Dominic White. We also thank Laren Friedman for creating the figures.
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