Fig. 1 Zika disease beliefs and conspiracy theory endorsement (representative survey). Means and 95% confidence intervals from the Brazil wave of the 2016 and 2017 AmericasBarometer survey (n = 1532; 5 April to 11 May 2017). “T” and “F” indicate true and false, respectively, for the outcome measures.
- Table 1 Correlates of Zika beliefs and misperceptions (survey data).
*P < 0.05, **P < 0.01, ***P < 0.005 (two-sided); OLS models estimated using survey weights. Data from the Brazil wave of the 2016 and 2017 AmericasBarometer survey (n = 1532; 5 April to 11 May 2017). Outcome variables are measures of factual belief about Zika and a composite measure indicating greater misperceptions about Zika, respectively (see the Supplementary Materials for wording). Respondents ages 16 to 30 are the reference category for age, and the north is the excluded category for region.
Spreads via mosquito Spreads via sex Spread via casual contact Misperception beliefs
(mean)Years of schooling 0.01 −0.05*** −0.05*** −0.08*** (0.01) (0.01) (0.01) (0.01) Moderate income −0.04 −0.22* −0.15 −0.05 (quartile 2) (0.05) (0.10) (0.08) (0.07) Medium income −0.01 −0.17 −0.17 −0.16* (quartile 3) (0.06) (0.13) (0.09) (0.08) High income 0.01 −0.25* −0.14 −0.14 (quartile 4) (0.06) (0.11) (0.08) (0.08) Male 0.06 0.00 0.02 −0.13* (0.04) (0.08) (0.06) (0.05) Age 31–45 0.08 −0.07 −0.06 0.03 (0.04) (0.08) (0.06) (0.06) Age 46–60 0.00 −0.16 −0.08 −0.09 (0.06) (0.11) (0.07) (0.08) Age 61 or older −0.05 0.07 0.24* 0.05 (0.08) (0.14) (0.11) (0.09) Urban 0.06 −0.08 −0.20*** −0.05 (0.07) (0.09) (0.07) (0.07) Northeast region 0.03 0.07 0.18*** 0.14 (0.08) (0.11) (0.06) (0.08) Center-west region −0.05 0.14 0.16 0.05 (0.09) (0.13) (0.10) (0.10) Southeast region 0.02 0.26* 0.20*** 0.15 (0.06) (0.10) (0.06) (0.08) South region −0.01 −0.08 0.11 0.03 (0.08) (0.13) (0.07) (0.09) Constant 3.53*** 2.75*** 2.07*** 3.31*** (0.10) (0.18) (0.11) (0.12) R2 0.01 0.05 0.07 0.14 n 1402 1331 1391 1284 - Table 2 Correction effects on targeted Zika misperceptions.
*P < 0.05, **P < 0.01, ***P < 0.005 (two-sided); OLS models with robust standard errors. Respondents are separate samples from Survey Sampling International’s online panel in Brazil. For each outcome measure, higher values indicate greater belief in the claim or claims in question [measured on a Likert scale ranging from “not at all accurate” (1) to “very accurate” (4); see the Supplementary Materials for wording]. All outcome measures are false.
Misperception beliefs
(mean)GMO mosquitoes caused
outbreakLarvicides responsible for
microcephalyVaccines responsible for
microcephalyA. 2017 Zika experiment Myths correction −0.00 −0.08 0.02 0.07 (0.04) (0.06) (0.05) (0.05) Constant 1.69*** 1.92*** 1.63*** 1.53*** (0.03) (0.04) (0.04) (0.04) n 1249 1260 1254 1255 B. 2018 Zika experiment Myths correction −0.06 −0.19*** 0.01 0.01 (0.05) (0.06) (0.06) (0.06) Constant (placebo) 1.68*** 1.89*** 1.62*** 1.55*** (0.03) (0.05) (0.04) (0.04) n 1049 1059 1062 1058 - Table 3 Correction effects on other Zika beliefs.
*P < 0.05, **P < 0.01, ***P < 0.005 (two-sided); OLS models with robust standard errors. Respondents are members of Survey Sampling International’s online panel in Brazil. For each outcome measure, higher values indicate greater belief in the claim or claims in question [measured on a Likert scale ranging from “not at all accurate” (1) to “very accurate” (4); see the Supplementary Materials for wording]. “T” and “F” indicate true and false, respectively, for the outcome measures.
(A) 2017 Zika experiment Causes neurological
problems (T)Spreads
via
mosquito
bite (T)Spreads via sexual
contact (T)Spread via casual contact (F) Myths correction −0.22*** −0.09*** −0.03 −0.10*** (0.06) (0.03) (0.07) (0.03) Constant (placebo) 3.01*** 3.85*** 1.98*** 1.25*** (0.04) (0.02) (0.05) (0.03) n 1259 1261 1260 1261 (B) 2018 Zika experiment Causes
neurological
problems (T)Spreads
via
mosquito
bite (T)Spreads
via sexual
contact (T)Spread via
casual
contact (F)Weak
immune more
vulnerable (F)Transmit
Zika in
utero (T)Zika increases
microcephaly (T)Get Zika
from
donated
blood (T)Microcephaly
causes
paralysis (F)Myths
correction−0.20*** −0.13*** −0.04 −0.04 −0.04 −0.15* −0.19*** −0.12 −0.10 (0.06) (0.04) (0.07) (0.04) (0.07) (0.06) (0.04) (0.07) (0.06) Constant
(placebo)3.00*** 3.83*** 1.86*** 1.26*** 2.71*** 3.37*** 3.69*** 2.54*** 2.82*** (0.04) (0.02) (0.05) (0.03) (0.05) (0.04) (0.03) (0.05) (0.04) n 1059 1061 1053 1061 1057 1056 1056 1059 1062 - Table 4 2018 yellow fever experiment results.
*P < 0.05, **P < .01, ***P < .005 (two-sided); OLS models with robust standard errors. Respondents are members of Survey Sampling International’s online panel in Brazil. For each outcome measure, higher values indicate greater belief in the claim or claims in question [measured on a Likert scale ranging from “not at all accurate” (1) to “very accurate” (4); see the Supplementary Materials for wording]. “Misperception belief” is a composite measure calculated as the mean of the three items listed. All misperception measures are false. “T” and “F” indicate true and false, respectively, for the other outcome measures.
(A) Correction effects on targeted yellow fever misperceptions Misperception beliefs
(mean)Yellow fever vaccine
ineffectiveLife-threatening
side effectsPropolis protects from yellow fever Myths correction −0.20*** −0.03 −0.20*** −0.38*** (0.04) (0.06) (0.06) (0.06) Constant (placebo) 1.98*** 1.82*** 2.00*** 2.13*** (0.03) (0.04) (0.04) (0.04) n 1063 1072 1072 1075 (B) Correction effects on other yellow fever beliefs Spreads
via
mosquito
bite (T)No
effective
vaccine (F)Same
mosquito as
Zika (T)Symptoms
include
fever,
vomiting (T)Disease
can be
fatal (T)Government
recommends
vaccine (T)Yellow fever
in cities (T)Vaccine
causes
immune
damage (F)Hoax by
drug
companies (F)Myths
correction0.04 0.01 0.36*** 0.02 −0.07* 0.11 0.03 −0.14* 0.03 (0.04) (0.05) (0.06) (0.04) (0.04) (0.06) (0.04) (0.06) (0.05) Constant
(placebo)3.77*** 1.55*** 3.10*** 3.68*** 3.82*** 3.09*** 3.51*** 2.01*** 1.45*** (0.03) (0.03) (0.05) (0.02) (0.02) (0.04) (0.03) (0.04) (0.03) n 1068 1077 1070 1075 1073 1073 1073 1074 1068
Supplementary Materials
Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/6/5/eaaw7449/DC1
Survey instruments
Additional results
Fig. S1. Beliefs about Zika (experimental data).
Table S1. Study summaries.
Table S2. Sample statistics.
Table S3. Treatment effects on Zika beliefs (experimental data).
Table S4. Treatment effects on Zika attitudes and behavioral intentions.
Table S5. Correction effects in 2017 Zika experiment (ordered probit).
Table S6. Treatment effects on Zika beliefs and attitudes (conspiracy predispositions).
Table S7. Treatment effects on Zika beliefs and attitudes (confidence in government).
Table S8. Treatment effects on Zika beliefs and attitudes (confidence in Ministry of Health).
Table S9. Treatment effects on Zika beliefs and attitudes (confidence in medicine).
Table S10. Treatment effects on Zika beliefs and attitudes (confidence in scientists).
Table S11. Correction effects on other Zika beliefs in 2017 Zika experiment.
Table S12. Correction effects on Zika beliefs and attitudes after delay.
Table S13. Treatment effects on Zika attitudes and behavioral intentions.
Table S14. Correction effects in 2018 Zika experiment (ordered probit).
Table S15. Treatment effects on Zika beliefs and attitudes (conspiracy predispositions).
Table S16. Treatment effects on Zika beliefs and attitudes (confidence in government).
Table S17. Treatment effects on Zika beliefs and attitudes (confidence in Ministry of Health).
Table S18. Treatment effects on Zika beliefs and attitudes (confidence in medicine).
Table S19. Treatment effects on Zika beliefs and attitudes (confidence in scientists).
Table S20. Correction effects on other Zika beliefs in 2018 Zika experiment.
Table S21. Treatment effect on perceived ability to discern truth about health/science.
Table S22. Treatment effects on yellow fever attitudes and behavioral intentions.
Table S23. Correction effects in 2018 yellow fever experiment (ordered probit).
Table S24. Treatment effects on yellow fever beliefs and attitudes (conspiracy predispositions).
Table S25. Treatment effects on yellow fever beliefs and attitudes (confidence in government).
Table S26. Treatment effects on yellow fever beliefs and attitudes (confidence in Ministry of Health).
Table S27. Treatment effects on yellow fever beliefs and attitudes (confidence in medicine).
Table S28. Treatment effects on yellow fever beliefs and attitudes (confidence in scientists).
Table S29. Treatment effect on perceived ability to discern truth about health/science.
Table S30. Correction effects on other Zika beliefs by pre-experiment response time.
Table S31. Correction effects on other Zika beliefs by experimental response time.
References (41–43)
Additional Files
Supplementary Materials
This PDF file includes:
- Survey instruments
- Additional results
- Fig. S1. Beliefs about Zika (experimental data).
- Table S1. Study summaries.
- Table S2. Sample statistics.
- Table S3. Treatment effects on Zika beliefs (experimental data).
- Table S4. Treatment effects on Zika attitudes and behavioral intentions.
- Table S5. Correction effects in 2017 Zika experiment (ordered probit).
- Table S6. Treatment effects on Zika beliefs and attitudes (conspiracy predispositions).
- Table S7. Treatment effects on Zika beliefs and attitudes (confidence in government).
- Table S8. Treatment effects on Zika beliefs and attitudes (confidence in Ministry of Health).
- Table S9. Treatment effects on Zika beliefs and attitudes (confidence in medicine).
- Table S10. Treatment effects on Zika beliefs and attitudes (confidence in scientists).
- Table S11. Correction effects on other Zika beliefs in 2017 Zika experiment.
- Table S12. Correction effects on Zika beliefs and attitudes after delay.
- Table S13. Treatment effects on Zika attitudes and behavioral intentions.
- Table S14. Correction effects in 2018 Zika experiment (ordered probit).
- Table S15. Treatment effects on Zika beliefs and attitudes (conspiracy predispositions).
- Table S16. Treatment effects on Zika beliefs and attitudes (confidence in government).
- Table S17. Treatment effects on Zika beliefs and attitudes (confidence in Ministry of Health).
- Table S18. Treatment effects on Zika beliefs and attitudes (confidence in medicine).
- Table S19. Treatment effects on Zika beliefs and attitudes (confidence in scientists).
- Table S20. Correction effects on other Zika beliefs in 2018 Zika experiment.
- Table S21. Treatment effect on perceived ability to discern truth about health/science.
- Table S22. Treatment effects on yellow fever attitudes and behavioral intentions.
- Table S23. Correction effects in 2018 yellow fever experiment (ordered probit).
- Table S24. Treatment effects on yellow fever beliefs and attitudes (conspiracy predispositions).
- Table S25. Treatment effects on yellow fever beliefs and attitudes (confidence in government).
- Table S26. Treatment effects on yellow fever beliefs and attitudes (confidence in Ministry of Health).
- Table S27. Treatment effects on yellow fever beliefs and attitudes (confidence in medicine).
- Table S28. Treatment effects on yellow fever beliefs and attitudes (confidence in scientists).
- Table S29. Treatment effect on perceived ability to discern truth about health/science.
- Table S30. Correction effects on other Zika beliefs by pre-experiment response time.
- Table S31. Correction effects on other Zika beliefs by experimental response time.
- References (41–43)
Files in this Data Supplement:
