Abstract
This study assesses public response to a proposed field trial in the United States of genetically engineered mosquito (OX513A) designed to suppress wild-type Aedes aegypti mosquitoes, which can transmit diseases such as Zika, dengue, and chikungunya.
Despite an increase in vector-borne diseases in the United States, there has been public opposition to novel vector control methods, particularly those that leverage advances in genetic engineering. In 2016, the US Food and Drug Administration (FDA) invited public comments on a draft environmental assessment for a proposed field trial of a genetically engineered mosquito (OX513A) designed to suppress wild-type Aedes aegypti mosquitoes, which can transmit diseases such as Zika, dengue, and chikungunya. Trials of OX513A in other countries have demonstrated reductions in numbers of A aegypti.
The environmental assessment indicated the trial would be unlikely to adversely affect the environment in Key Haven, Florida, the proposed trial site. We assessed public response to this proposed trial based on the content of public comments submitted to the FDA because the views expressed in such public forums may influence testing and deployment. In addition, given that individual informed consent for such environmental interventions is not feasible, efforts to understand and respond to public concerns are critical for maintaining public trust in public health activities.
Methods
The study was deemed exempt by the University of California, San Diego, institutional review board. Transcripts of comments from self-selected respondents to docket FDA-2014-N-2235 between March 11, 2016, and May 16, 2016, were obtained through the Freedom of Information Act. Content analysis was used to classify each comment as opposed, neutral, or supportive of the trial, and thematic analysis using both inductive and deductive approaches was conducted to identify additional themes in the data. To assess reliability, a primary rater coded all comments and a secondary rater coded a random 10% for each code (κ = 0.98 for opposed, neutral, and supportive classifications). Comments that included respondent zip code were geocoded and linked to publicly available geographic and sociodemographic data. Using SPSS Statistics (IBM), version 23, the Mood median test and χ2 test for trend were used to analyze characteristics of comments and themes. A 2-sided P value less than .05 was considered significant.
Results
Of 2649 comments submitted to the FDA, 2624 were analyzed after quality control. Median word count was 57.0 and 82.8% were from individuals. Most comments (74.8%) were opposed, 3.6% were neutral, and 21.6% were supportive of the trial (Table 1). Themes identified were ecological safety (51.2%), human health implications (67.3%), genetically modified organisms generally (65.1%), and mistrust of government or industry (23.6%). The greatest differences between comments opposing vs supporting were for human health (61.4% opposing comments vs 86.8% supporting comments; difference, −25.4%) and mistrust of government or industry (30.1% opposing comments vs 1.4% supporting comments; difference, 28.7%). Zip codes were available from 1125 comments (42.9%). Opposition was significantly associated with zip codes with micropolitan areas, higher elevations, lower average house values, and lower household incomes (Table 2).
Table 1. Description of and Themes Present in Public Comments by Attitude Toward the Use of Genetically Engineered Mosquitoes in a Field Trial Reviewed by the US Food and Drug Administration.
| Variable | No. of Public Comments (%) | Between-Group Difference for Opposed vs Supported, % (95% CI) | P Value | ||
|---|---|---|---|---|---|
| Opposed | Neutral | Supported | |||
| Total No. of commentsa | 1962 (74.8) | 95 (3.6) | 567 (21.6) | NA | NA |
| Characteristics | |||||
| No. of words in the comment, median (IQR)b | 52.0 (74)c | 74.0 (122)c | 77.0 (65)c | NA | <.001d |
| Submitter category (% individual consumer)e | 1639 (83.5) | 79 (83.2) | 455 (80.2) | NA | .07f |
| Anonymousg | 562 (28.6) | 23 (24.2) | 119 (21.0) | NA | <.001f |
| Zip code providedh | 809 (41.2) | 44 (46.3) | 272 (48.0) | NA | .004f |
| Comment Themei | |||||
| Ecological safetyj | 962 (49.1) | 61 (64.9) | 320 (56.4) | −7.4 (−12.1 to 2.6) | .001f |
| Human healthj | 1205 (61.4) | 70 (74.5) | 492 (86.8) | −25.4 (−28.8 to −21.6) | <.001f |
| Genetically modified organismsj | 1331 (67.8) | 55 (57.9) | 322 (56.8) | 11 (6.4 to 15.7) | <.001f |
| Mistrust of government or industryj,k | 590 (30.1) | 19 (20.4) | 8 (1.4) | 28.7 (26.2 to 30.9) | <.001f |
Abbreviations: IQR, interquartile range; NA, not applicable.
In response to the Freedom of Information Act request, 2649 comment transcripts were received; 25 of these were removed because they were duplicates (17 comments), they were found to be blank (7 comments), or the comment was completely unrelated to genetically engineered mosquitoes and likely submitted in error (1 comment).
Median word count for all comments was 57.
Post hoc pairwise comparisons using the Mood median test revealed significant differences between opposed vs neutral (P < .02), supportive vs neutral (P < .002), and opposed vs supportive (P < .001).
Mood median test.
Submitter category was selected by the respondent. A total of 26 categories were represented. “Individual consumer” was the most-frequent category (82.8%), “academia” was the second most-frequent category (2.7%), and “health professional” was the third most-frequent category (2.4%).
χ2 test for trend.
Anonymous was defined as the absence of both first and last name.
Of the 1125 comments submitted with zip code, there were 940 unique zip codes represented; the majority of comments with zip code came from Florida (n = 293) and California (n = 147), with South Dakota being the only US state not represented. Zip codes with the most submitted comments included 33040 (Key West, Florida; n = 42), 33037 (North Key Largo, Florida; n = 8), and 32952 (Merritt Island, Florida; n = 8).
Themes were generated both a priori based on existing literature and expert opinion and from the raw data itself as coding proceeded, consistent with the literature on qualitative data analysis. Although each comment was rated as being either opposed, neutral, or supportive and could only be assigned to 1 of these categories, with respect to the thematic analysis, a single comment could have been categorized in multiple thematic categories (eg, ecological safety and human health).
Sample sizes were as follows: ecological safety (n = 2622), human health (n = 2622), genetically modified organisms (n = 2624), and mistrust of government or industry (n = 2615). κ statistics were 0.81 for ecological safety, 0.77 for human health, 0.75 for genetically modified organisms, 0.73 for mistrust of government, and 0.95 for mistrust of industry.
Initial coding and reliability assessment of mistrust of US government produced a κ of less than .70; therefore, specific discrepancies were discussed among the first 2 raters, the rating criteria revised, and a random subset of 265 comments were subjected to another round of coding with a third rater.
Table 2. Relationship Between Zip Code–Based Geographic and Sociodemographic Factors and Geocoded Attitudes Toward the Use of Genetically Engineered Mosquitoes.
| Opposed, Median (IQR) (n = 809 Comments) |
Neutral, Median (IQR) (n = 44 Comments) |
Supported, Median (IQR) (n = 272 Comments) |
P Value | P Value for Post Hoc Pairwise Testsa | |||
|---|---|---|---|---|---|---|---|
| Opposed vs Neutral | Supported vs Neutral | Opposed vs Supported | |||||
| Geographic Variablesb | |||||||
| Area, square milesc | |||||||
| Land | 18.5 (7.3-50.1) | 21.9 (7.9-65.0) | 11.8 (5.3-26.1) | <.001d | .98 | .03 | <.001 |
| Water | 0.37 (0.05-1.92) | 0.60 (0.02-2.62) | 0.37 (0.02-2.23) | .65d | NA | NA | NA |
| Elevation, fte | 174.0 (21.0-746.0) | 333.5 (31.2-845.5) | 57.0 (16.0-536.0) | .01d | .62 | .05 | .005 |
| Micropolitan, No. (%)f | 126 (16.2) | 11 (26.2) | 25 (9.4) | .02g | NA | NA | NA |
| Sociodemographic Variablesb | |||||||
| House value, $h | 208 700 (137 250-349 000) |
205 900 (133 750-328 875) |
288 350 (172 325-451 275) |
<.001d | .88 | .002 | <.001 |
| Income per household, $h | 53 581 (43 475-70 107) |
55 175 (44 504-67 886) |
60 306 (48 840-84 959) |
<.001d | .62 | .42 | <.001 |
| Age, yi | 40.3 (35.8-43.7) | 41.4 (35.8-44.0) | 40.2 (34.9-43.8) | .46d | NA | NA | NA |
| Female proportioni,j | 0.51 (0.50-0.52) | 0.51 (0.50-0.52) | 0.51 (0.50-0.52) | .04d | .64 | .14 | .02 |
| Race/ethnicity proportion | |||||||
| Asiani,j | 0.03 (0.01-0.06) | 0.02 (0.01-0.04) | 0.04 (0.02-0.10) | <.001d | .02 | <.001 | <.001 |
| Black or African Americani,j | 0.05 (0.02-0.10) | 0.05 (0.01-0.12) | 0.05 (0.02-0.10) | .41d | NA | NA | NA |
| Hawaiian or Pacific Islanderi,j | 0.002 (0.001-0.003) |
0.002 (0.001-0.002) |
0.002 (0.001-0.004) |
.91d | NA | NA | NA |
| Hispanicj,k | 0.09 (0.04-0.19) | 0.06 (0.02-0.20) | 0.09 (0.05-0.14) | .77d | NA | NA | NA |
| American Indian or Alaska Nativej,k | 0.01 (0.01-0.02) |
0.01 (0.008-0.014) |
0.01 (0.006-0.014) |
.002d | .27 | .25 | .001 |
| Whitei,j | 0.86 (0.74-0.93) | 0.86 (0.70-1.00) | 0.84 (0.71-0.91) | .12d | NA | NA | NA |
Abbreviations: IQR, interquartile range; NA, not applicable.
Post hoc pairwise Mood median tests.
Data retrieved via CDXZipCode data feed on July 2016.
Source: US Census Bureau.
Mood median test.
Source: National Elevation Dataset of the US Geological Survey, converted to county by ZipCode World (all zip codes within a county were considered to have the same elevation).
Core-based statistical area defined by the US Office of Management and Budget. Total sample size was 1089 comments (opposed, 780; neutral, 42; supported, 267).
χ2 test for trend.
Source: 2010-2014 aggregated American Community Survey.
Source: 2010 census.
Total sample size was 1106 comments (opposed, 794; neutral, 42; supported, 270).
Source: 2000 and 2010 census.
Discussion
This study found that members of the public who responded to a federal document had predominately negative views on the use of genetically engineered mosquitoes. Even though this group is unlikely representative of the general public, the vocal minority who have expressed views on this topic have influenced whether and where field trials may go forward, and therefore, it is worthwhile to understand those views. In August 2016, the FDA concluded that the proposed trial of OX513A would be unlikely to harm the environment. Due to opposition from the residents of Key Haven, Florida, however, the local mosquito control board did not approve the trial. Instead, 2 nonbinding referendums were put on the November ballot, 1 for Key Haven residents (35% in favor), and 1 for all of Monroe County (58% in favor). The mosquito control board then approved the trial but moved the trial site to another Monroe County location.
The associations observed between some demographic factors and opposed views might inform approaches to future public engagement strategies regarding the use of genetically engineered mosquitoes. Limitations of the study include the self-selected response and lack of information on respondent-level covariates. Future studies that incorporate representative sampling and evaluate educational attainment, media coverage, and proximity to A aegypti are required.
Section Editor: Jody W. Zylke, MD, Deputy Editor.
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