Table 1 Identified studies on infection-preventive behavior

Allington et al. [30]

Study 1: 3.4–7.4 2020

Study 2: 1.4–3.4 2020

Study 3: 20.5–22.5 2020

Study 1: N = 949, Mage (SD) = 36.35 (10.49); Study 2: N = 2250, Mage (SD) = 45.47 (17.66); Study 3: N = 2254, Mage (SD) = 43.93 (16.11); sample of UK-residents, Study 1: non-representative sample, Study 2 and 3: national representativeness with regard to age, gender, region, working status, social grade and education

Health-protective behavior

Study 1: 6 items on three conspiracy narratives on the origin of COVID-19 (true/false), 6 items on health-protective behaviors (yes/no); Study 2: 1 item on conspiracy belief, 5 items on health-protective behavior; Study 3: 5 items on conspiracy belief, 4 items on health-protective behavior

Study 1: Sig. negative relationship between conspiracy belief and health-protective behavior: OR = 0.46, 95% CI [0.34, 0.61], p < 0.001; Study 2: Sig. negative relationship between conspiracy belief and health-protective behavior: OR = 0.50, 95% CI [0.39, 0.66], p < 0.001; Study 3: Sig. negative relationship between conspiracy belief and health-protective behavior: OR = 0.37, 95% CI [0.29, 0.47], p < 0.001

Alper et al. [24]

Not reported

N = 1088, Mage (SD) = 31.02 (39.43), non-representative Turkish sample

Preventive measures

Conspiracy belief: 2 items; preventive measures: 7 items, scale from 1 (strongly disagree) to 7 (strongly agree)

Correlation of conspiracy belief and preventive measures not significant: r = 0.02, p = 0.526

Biddlestone et al. [33]

4.4–13.4 2020

N = 704, Mage (SD) = 37.26 (2.51), non-representative international sample (66 nationalities, mainly from the USA and UK)

Behaviors that reduce the spread of COVID-19

Conspiracy belief: 10 items, scale from 1 (strongly disagree) to 7 (strongly agree); 12 items, scale from 1 (definitely not) to 5 (definitely yes) behaviors that reduce the spread of COVID-19 (8 items social distancing intentions, 4 items hygiene intentions)

Negative, n. sig. association of hygiene intentions and conspiracy belief: r = − 0.02; negative sig. association of social distancing intentions and conspiracy belief: r = − 0.16, p < 0.001; conspiracy belief is a negative predictor of social distancing intentions in the SEM model: β = − 0.04, p < 0.001

Bierwiaczonek et al. [27]

16.3–20.4 2020

N = 403, Mage (SD) = 37.42 (11.14), non-representative US American sample

Social distancing

Conspiracy belief: 3 items, scale from 1 (not at all) to 7 (very much) on three commonly shared conspiracy theories; 3 items, scale from 1 (strongly disagree) to 5 (strongly agree) on willingness to practice social distancing during the COVID-19 pandemic

Conspiracy belief predicts less social distancing at a later wave (T): Conspiracy belief T1 and social distancing T2: β = − 0.067, p = 0.002; Conspiracy belief T2 and social distancing T3: β = − 0.065, p = 0.002; Conspiracy belief T3 and social distancing T4: β = − 0.063, p = 0.002; Conspiracy belief T4 and social distancing T5: β = − 0.062, p = 0.002

Earnshaw et al. [28]

13.4–14.4 2020

N = 845, Mage (SD) = 40.15 (11.67), non-representative US American sample

Complying with Public Health Recommendations

6-item questionnaire on different conspiracy narratives (agree/disagree); 8-item questionnaire on complying with public health recommendations (never, rarely, often, always)

No sig. association between complying with public health recommendations and conspiracy belief: b (SE) = − 0.04 (0.05), β = 0.2

Freeman et al. [23]

4.5–11.5 2020

N = 2501, Mage (SD) = 46.6 (17.3), English sample, quota sampled to match the population for age, gender, income, and region

Following of UK government coronavirus guidance/future medical tests and treatments

Coronavirus conspiracy explanations: 48 items, scale from 1 (do not agree) to 5 (agree completely); Adherence to the government recommendations: 8 items, scale from 1 (not at all) to 5 (all of the time); Future medical tests and treatments: 6 items, scale from 1 (definitely) to 5 (definitely not)

Sig. negative association of conspiracy belief and adherence to guidelines/medical tests and treatments: r (− 0.27 to − 0.47), p < 0.001; Negative sig. association of conspiracy belief and adherence to guidelines: Conspiracy belief that COVID-19 is a bioweapon correlates negative with staying at home (OR = 4.57, 95% CI [3.62, 5.79]), endorsing the conspiracy narrative that Jews have created the virus to collapse the economy for financial gain was negatively associated with adhering to the guidance to stay at home (OR = 14.34, 95% CI [11.26, 18.25])

Garry et al. [31]

16.7–19.7 2020

N = 1045, representative sample of the English population in terms of gender, age, Government Office Region and 2019 vote

Adherence to current and future guidelines

6 items on different conspiracy narratives (strongly disagree, disagree, slightly disagree, slightly agree, agree, strongly agree, don’t know); 3 items on adherence to current guidelines, scale from 1 (not at all) to 7 (completely), 5 items on adherence to future guidelines (yes definitely, yes probably, no probably not, no definitely not, don’t know)

Conspiracy belief predicts current and future non-adherence significantly: b (SE) = 0.32 (0.03), β = 0.36, p < 0.001; future: b (SE) = 0.35 (0.03), β = 0.38, p < 0.001

Imhoff and Lamberty [32]

20.3–25.3 2020

Study 1: N = 220, Mage (SD) = 40.18 (12.33), US American sample; Study 2a: N = 288, Mage (SD) = 36.60 (11.16), US American sample;Study 2b: N = 298, Mage (SD) = 37.29 (12.79), sample from UK; non-representative samples

Containment-related behavior

Conspiracy belief: two sets (COVID-19 hoax and SARS-CoV-2 human-made) with 3 items each, scale from 1 (strongly disagree) to 7 (strongly agree); 7 items on containment-related behavior, scale from 1 (never) to 7 (always/strongly)

Study 1: Sig. negative association between conspiracy belief COVID-19 is a hoax and containment-related behavior: r = − 0.356, p < 0.002; b (SE) = − 0.647 (0.109), p < 0.001; Association conspiracy belief SARS-CoV-2 human-made and containment-related behavior n. sig. r = − 0.123 (n. sig.); b (SE) = 0.104 (0.104), p = 0.319; Study 2: Negative association between COVID-19 hoax and containment-related behavior: Study 2a: r = − 0.524 (sig.), b (SE) = − 0.834 (0.092), p < 0.001; Study 2b: r = − 0.154 (n. sig.), b (SE) = − 0.397 (0.109), p < 0.001); Association SARS-CoV-2 human-made: Study 2a: r = − 0.307 (sig., p < 0.001); b (SE) = 0.104 (0.093), p = 0.265; Study 2b: r = 0.014 (n. sig.), b (SE) = 0.154 (0.082), p = 0.061)

Kowalski et al. [25]

11.4–14.4 2020; 21.4–28.4 2020

Study 1: N = 507, Mage (SD) = 44.07 (14.41), representative Polish sample in terms of gender and settlement size; Study 2: N = 840, Mage (SD) = 29.94 (10.39), non-representative Polish sample

Adherence to safety guidelines

14-item (Study 1) and 12-item questionnaire (Study 2) on different conspiracy narratives, scales from 1 (strongly disagreeing) to 7 (strongly agreeing); 4-item (Study 1) and 5-item questionnaire (Study 2) on adherence to safety and self-isolation guidelines, 7-level scale

Sig. negative association between conspiracy belief and adherence to safety guidelines: rs = − 0.22; conspiracy belief predicted adherence to safety guidelines (sig.): Study 1: b (SE) = − 0.05 (0.01), p ≤ 0.001; Study 2: b (SE) = − 0.08 (0.01), p < 0.001

Oleksy et al. [26]

13.3–15.3 2020

Study 1: N = 1046, representative Polish sample in terms of gender, age and size of residence

Protective behavior

Conspiracy belief: 3 items on general conspiracy narratives, 2 items on government-related conspiracy narratives; Protective behavior: 9 items (yes/no)

Government-related and general conspiracy belief correlated n. sig. with protective behavior: r = 0.01 and r = 0.05; Government-related conspiracy belief sig. negatively predicted protective behavior: b (SE) = − 0.04 (0.02); General conspiracy belief n. sig.: b (SE) = 0.02 (0.02)

Romer and Jamieson [29]

17.3–27.3 2020; 10.7–21.7 2020

N = 840, representative US American sample in terms of age, gender, race/ethnicity and education

Taking of preventive actions

Conspiracy belief: 3-item questionnaire (3 different conspiracy narratives), scale from 1 (definitely false) to 4 (definitely true); Preventive actions: list of 9 actions to prevent further spread of COVID-19 (yes/no)

Conspiracy belief in March sig. predicted actions taken in July: β = −0.16, 99% CI [− 0.26, − 0.07], p ± 0.005

Teovanović et al. [22]

10.4–22.4 2020

N = 407, Mage (SD) = 34.88 (12.81), non-representative Serbian sample

Adherence to COVID-19 guidelines by the WHO and the Serbian Ministry of Health

13 items on conspiracy belief, scale from 1 (completely disagree) to 5 (completely agree); 12 items on adherence to guidelines, thereof 5 items on preventive behavior on a scale from 1 (never) to 5 (very often), 7 items on avoided risk behaviors (never, once, twice, three times, > three times)

Conspiracy belief sig. negatively correlated with the adherence to COVID-19 guidelines: r = −0.17 p < 0.05; Conspiracy belief was a sig. negative predictor for adherence to COVID-19-guidelines: b (SE) =  − 0.09 (0.03), 95% CI [− 0.14, − 0.04], p = 0.001