Table 1 Characteristics of quantative included studies related to COVID-19 conspiracy beliefs and theories

Agley and Xiao [18]

USA

Cross-sectional

Convenience

N = 660, general population,

Mean age = 24.8

% Female = 32.3

Ethnicity = White, Hispanic, Black or African, American,Asian and others

A list of five COVID-19 conspiracy beliefs (5G, Bill Gates,

Zoonotic, Laboratory development as military weapon, Liberty restriction)

using a Likert-type scale (1 = Extremely unbelievable to 7 = Extremely believable)

5G: Mean = 1.94 (SD =  ± 1.72)

Zoonotic: Mean = 5.56 (SD =  ± 1.64)

Bill Gates: Mean = 2.27 (SD =  ± 1.88)

Laboratory: Mean = 3.28 (SD =  ± 2.00)

Liberty Restriction: Mean = 2.96 (SD =  ± 2.04)

Profile 1 (n = 463, 70.15%), the largest class, generally believed the scientific consensus narrative about COVID-19 and tended not to believe in other conspiracy beliefs

Profile 2 (n = 54, 8.18%) considered all of the conspiracy beliefs to be highly plausible

Profile 3 (n = 77, 11.67%) reported low-to-moderate believability for all of the conspiracy beliefs

Profile 4 (n = 66, 10%) reported fairly high believability for most conspiracy beliefs

High

Allington et al. [29]

UK

Cross-sectional

Study 1: Convenience

Study 2 and 3: Stratified random sampling

Study 1: N = 949, general population, Mean age = 36.3, Female = 

68.3, Ethnicity = NR

Study 2: N = 2250, general population, Mean age = 45.5, % Female = 51.3, Ethnicity = NR

Study 3: N = 2254, general population, Mean age = 43.9, % Female = 49.9, Ethnicity = NR

Study 1:A list of three COVID-19 conspiracy beliefs (Laboratory development, 5G Intentional spread)

Study 2: On item that coronavirus was probably created in a laboratory

Study 3: A list of five COVID-19 conspiracy beliefs (Laboratory development, 5G, Intentional spread, not really exist, part of a global effort to force everyone to be vaccinated)

NR

Study 1: 24.24% believed that COVID-19 was probably created in a laboratory. 5.16% believed on 5G conspiracy theory. 9.8% believed that pandemic was planned by certain pharmaceutical corporations

Study 2: 24.6% believed that coronavirus was probably created in a laboratory

Study 3: 0.14% believed that COVID-19 was probably created in a laboratory. 8.13% believed on 5G conspiracy theory. 7.32% believed that coronavirus did not really exist. 13.74% believed that dying from coronavirus is being deliberately exaggerated by the authorities and 12.67% believed that pandemic is part of a global effort to force everyone to be vaccinated

Moderate

Alper [39]

Turkey

Cross-sectional

Convenience

N = 1088, general population,

Mean age = 31.0

% Female = 72.6

Ethnicity = NR

A list of two COVID-19 conspiracy theories (Intentional spread or

natural spread no intention) using a Likert-type scale (1 = strongly disagree, to 7 = strongly agree) and the 15-item Generic Conspiracist Beliefs Scale

Intentional spread: Mean = 2.91 (SD =  ± 1.72)

Generic conspiracist beliefs: Mean = 2.53 (SD =  ± 0.78)

NR

High

Bertin et al. [49]

France

Cross-sectional

Convenience

Study 1:N = 409, general population,

Mean age = 28.4

% Female = 73.1

Ethnicity = NR

Study 2:N = 469, general population,

Mean age = 26.1

% Female = 59.7

Ethnicity = NR

Study 1:A list of COVID-19 conspiracy beliefs involving a threatening foreign outgroup (e.g., China) and theories involving unspecified outgroup or members of the national ingroup (e.g., French government)

Study 2: same scale as in Study 1, and added a conspiracy theory about the creation of the coronavirus by a famous French laboratory

Study 1:Outgroup COVID-19 conspiracy beliefs: Mean = 1.44 (SD =  ± 0.69)

Ingroup COVID-19 conspiracy beliefs: Mean = 2.47 (SD =  ± 0.97)

Study 2: Outgroup COVID-19 conspiracy beliefs: Mean = 1.60 (SD =  ± 0.69)

Ingroup COVID-19 conspiracy beliefs: Mean = 2.60 (SD =  ± 0.94)

Chloroquine conspiracy beliefs: Mean = 2.47 (SD =  ± 0.97)

NR

High

Biddlestone et al. [54]

UK

Cross-sectional

Convenience

N = 704, general population,

Mean age = 37.3

% Female = 53.4

Ethnicity = British, American, other

A list of three COVID-19 conspiracy beliefs (5G, Laboratory development, Intentional spread using a Likert-type scale (1 = strongly disagree, to 7 = strongly agree)

Overall COVID‐19 conspiracies: Mean = 1.50 (SD =  ± 0.57)

NR

Moderate

Bierwiaczonek et al. [55]

USA

Longitudinal

Convenience

N = 403, general population,

Mean age = 37.4

% Female = 45.9

Ethnicity = Caucasian, African American, Hispanic, Asian, Native American, other

A list of three COVID-19 conspiracy beliefs (Human made, Laboratory development as military weapon, Intentional spread using a Likert-type scale (1 = not at all, to 7 = very much)

Human made Mean = 3.14 (SD =  ± 1.99)

Laboratory development as military weapon Mean = 3.06 (SD =  ± 1.92)

Intentional spread: Mean = 2.83 (SD =  ± 1.92)

NR

High

Čavojová et al. [56]

Slovakia

Cross-sectional

Convenience

N = 783, general population,

Mean age = 42.0

% Female = 53.3

Ethnicity = NR

A list of various conspiracy theories (Intentional spread, Vaccination narrative,Bill Gates narrative (+ microchip) on a 5-point scale

Overall COVID‐19 conspiracies: Mean = 2.07 (SD =  ± 0.87)

NR

Moderate

Chen et al. [57]

Ecuador

Cross-sectional

Convenience

N = 252, health care workers

Mean age = NR, Age =  > 18 years

% Female = 65.5

Ethnicity = NR

A list of various conspiracy theories (Intentional spread, natural spread no intention, Laboratory accident, not sure) in a yes or no response

NR

Intentional spread: n = 61, 24.2%

Natural spread: n = 52, 20.6%

Laboratory accident: n = 35, 13.9%

Not sure: n = 104, 41.3%

High

Duplaga [58]

Poland

Cross-sectional

Representative

N = 1002, general population,

Mean age = 40.1

% Female = 50.6

Ethnicity = Polish

Items asking for opinions about three popular conspiracy theories related to COVID-19 (Genetic manipulations carried out by man, to spread panic and to achieve a political aim, as a pretext for the introduction of total surveillance of the population on a 5-point scale

NR

Genetic manipulations carried out by man: n = 459, 45.8% (both agree and decidedly agree)

To spread panic and to achieve a political aim: n = 418, 42.7% (both agree and decidedly agree)

As a pretext for the introduction of total surveillance of the population: n = 562, 56% (both agree and decidedly agree)

Moderate

Earnshaw et al. [19]

USA

Cross-sectional

Convenience

N = 845, general population,

Mean age = 40.1

% Female = 40.9

Ethnicity = Asian, Black, Latin, White, Other

Conspiracy beliefs were measured with six items modeled after a measure of HIV conspiracy beliefs (5G,Vaccination narrative, Intentional spread as bioweapons program, no such thing as the coronavirus, government could cure coronavirus, but chooses not to for financial)

Average of conspiracy beliefs: Mean = 3.11 (SD =  ± 1.80)

One or more conspiracy COVID‐19 beliefs: n = 279, 33%

High

Fountoulakis et al. [20]

Greece

Ccross-sectional

Convenience

N = 3399, general population,

Mean age = 34.0

% Female = 81.1

Ethnicity = NR

A list of various conspiracy theories (5G, Laboratory development, Intentional spread) on a 5-point scale

NR

Beliefs in conspiracy theories seem widely prevalent with the more bizarre (like the relationship between COVID-19 and 5G, or the involvement of a supernatural power) enjoying lower acceptance. However, on average at least half of cases accepted at least to a moderate degree some non-bizarre conspiracy including the deliberate release of the virus as a bioweapon to deliberately create a global crisis (numbers not given)

Moderate

Freeman et al. [22]

UK

Cross-sectional

Convenience

N = 2501, general population

Mean age = 46.6

% Female = 50.65

Ethnicity: White English / Welsh / Scottish / Northern Irish / British = 80.3%

Oxford Coronavirus Explanations, Attitudes, and Narratives Survey (OCEANS) coronavirus general conspiracy seven-item, a 14-item-specific coronavirus conspiracy scale on a 5-point scale

Mean total generic coronavirus conspiracy score: Mean = 3.41 (SD =  ± 1.70)

Μean total specific coronavirus conspiracy score: Mean = 46.1 (SD =  ± 26.0)

Mean total score for the four official explanations (scepticism, Conspiracy cause of the virus, The spread of the virus is a deliberate attempt, conspiracy reasons for lockdown): Mean = 12.9 (SD =  ± 3.40)

50% of participants showed little evidence of conspiracy thinking, 25% showed a degree of endorsement, 15% showed a consistent pattern of endorsement, and 10% had very high levels of endorsement

Conspiracy cause of the virus:

21% = the virus is a hoax

62.3% = the virus is manmade

48.9% = the virus is produced by powerful organisations (e.g., government, military)

The spread of the virus is a deliberate attempt:

42.4% = to reduce the size of the global population

41.6% = by governments to gain political control

38.9% = aby a group of powerful people to make money

Conspiracy reasons for lockdown:

24.2% = to stop immigration

38.9% = to control every aspect of our lives

37.7% = to impose mass surveillance

32.6% = to destabilise the nation for political gain

Specific Conspiracy Beliefs:

45.4% = Coronavirus is a bioweapon developed by China to destroy the West

28.3% = The virus is a biological weapon manufactured by the United States

21% = Bill Gates has created the virus in order to reduce the world population

21.3% = Coronavirus is caused by 5 G and is a form of radiation poisoning transmitted through radio waves

28.5% = Coronavirus is being used by the government to implement a police state

24.6% = Big Pharma created coronavirus to profit from the vaccines

Moderate

Freeman et al. [21]

UK

Cross-sectional

Convenience

N = 5114, general population

Mean age = 46.9

% Female = 50.35

Ethnicity: White English / Welsh / Scottish / Northern Irish / British = 79.3%

Oxford Coronavirus Explanations, Attitudes, and Narratives Survey (OCEANS) coronavirus general conspiracy seven-item, a 14-item-specific coronavirus conspiracy scale on a 5-point scale

NR

Endorsement of coronavirus conspiracy beliefs:

22.6% = the virus is a hoax

56.8% = the virus is manmade

39.5% = The spread of the virus is a deliberate attempt to reduce the size of the global population

36.5% = The spread of the virus is a deliberate attempt by governments to gain political control

35.9% = The spread of the virus is a deliberate attempt by a group of powerful people to make money

40.5% = COVID-19 is a bioweapon developed by China to destroy the West

23.6% = The virus is a biological weapon manufactured by the United States

20.7% = Bill Gates has created the virus in order to reduce the world population

24.1% = Big Pharma created COVID-19 to profit from the vaccines

33% = COVID-19 is being used by the government to implement a police state

20.1% = COVID-19 is caused by 5 G and is a form of radiation poisoning transmitted through radio waves

23.1% = The vaccine will be used to carry out mass sterilisation

Moderate

Garry [23]

UK

Cross-sectional

Representative

N = 2057, general population,

Mean age = NR

% Female = NR

Ethnicity = English

10 statements with which respondents are asked to either agree or disagree

In the ‘best practice’ condition, the response options include the following options:’’strongly disagree, disagree, slightly disagree, slightly agree, agree, strongly agree, don't know’’

NR

31.7% = Coronavirus is a bioweapon developed by China to destroy the West

13.4% = Muslims are spreading the virus as an attack on Western values

17.2% = Lockdown is a plot by environmental activists to control the rest of us

17.1% = The coronavirus vaccine will contain microchips to control the people

18.8% = The United Nations (UN) and World Health Organisation (WHO) have manufactured the virus to take global control

10.6% = Jews have created the virus to collapse the economy for financial gain

High

Georgiou et al. [24]

Multisite

Cross-sectional

Convenience

N = 640, general population,

Mean age = NR, Age =  > 18 years

% Female = 49.5

Ethnicity = NR

A 9-item COVID-19 conspiracy scale (5G,Vaccination narrative, Intentional spread as bioweapons program) on a 7-point scale ranging from 1 = Strongly disagree to 7 = Strongly degree

The beliefs in conspiracy theory inventory (BCTI) and the generalised conspiracy beliefs scale (GCBS)

Average COVID conspiracy scale: Mean = 27.0 (SD =  ± 10.25),

General conspiracy beliefs (GCBS): Mean = 35.10 (SD =  ± 13.60),

Specific conspiracy beliefs (BCTI): Mean = 50.5 (SD =  ± 25.6)

NR

High

Hursh et al. [26]

USA

Cross-sectional

Convenience

N = 534, general population,

Mean age = 41.9,

% Female = 51.0,

Ethnicity = White

Generic Conspiracist Beliefs scale (GCB)

GCB scale: Mean = 70.4 (SD =  ± 21.7)

NR

High

Jolley et al. [62]

UK

Cross-sectional

Convenience

N = 534, general population,

Mean age = 34.3,

% Female = 49.5,

Ethnicity = Britons

Belief in 5G COVID‐19 conspiracy theories was measured with five items

Belief in 5G COVID‐19: Mean = 1.93 (SD =  ± 1.38)

NR

Moderate

Jovančević and Milinsevic [27]

Serbia and Latin America

Cross-sectional

Convenience

N = 412 (general population,

Mean age = 31.9,

% Female = 82.3,

Ethnicity = 292 Serbian and 120 Latin American

One item that the virus was created in the laboratory on purpose

Belief in COVID‐19 lab conspiracy: Serbians Mean = 3.18 (SD =  ± 1.24)

Belief in COVID‐19 lab conspiracy: Latin Americans: Mean = 3.18 (SD =  ± 1.53)

NR

Moderate

Kaparounaki [28]

Greece

Cross-sectional

Convenience

N = 1000 (general population,

Mean age = 22.1,

% Female = 68.0,

Ethnicity = NR

Questions to assess beliefs in conspiracy theories including those pertaining to COVID-19

NR

35% believed in one or more conspiracy theories while 20% have a neutral but open approach. For covid-19, 29% believe it is a laboratory product (23% neutral), 25% that the spreading was a deliberate covert action (22% neutral) and 24% that it was developed as a bioweapon (22% neutral)

Moderate

Kim and Kim [30]

Korea

Cross-sectional

Representative

N = 3399, general population,

Mean age = NR

% Female = 52.1

Ethnicity = NR

A seven-item questionnaire for various beliefs in conspiracy theories

NR

17.9% of respondents supported that the government is always monitoring the public. 2.8% of respondents agreed that certain powerful nations deliberately created the coronavirus (COVID-19) to dominate the world and 8% agreed that coronavirus disease (COVID-19) was deliberately created by pharmaceutical companies to make money

High

Kowalski and Gaweda [31]

Poland

Longitudinal

ΝR

N = 110, general population,

Mean age = NR

% Female = 52.1

Ethnicity = NR

A 12-items questionnaire for various beliefs in conspiracy theories on a seven-point Likert scale

NR

NR

Moderate

Kowalski, et al. [32]

Poland

Cross-sectional

Proportional quota and convenience

Study 1: N = 507, general population,

Mean age = 44.1

% Female = 49.9

Ethnicity = NR

Study 2: N = 840, general population,

Mean age = 29.9

% Female = 72.3

Ethnicity = NR

Study 1:A 14-items questionnaire for various beliefs in conspiracy theories on a seven-point Likert scale

Study 1: A 12-items questionnaire for various beliefs in conspiracy theories on a seven-point Likert scale

NR

Study 1: 32.1% declared full agreement with at least one conspiracy theory (13% when government conspiracy is excluded)

Study 2: 17% declared full support for at least one conspiracy theory

Moderate

Latkin et al. [33]

USA

Cross-sectional

Convenience

N = 683, general population,

Mean age = 39.1

% Female = 55.5

Ethnicity = NR

One question for COVID-19 related to China purposely spread the coronavirus on a five-point Likert scale

NR

13.3% (n = 91) agreed or strongly agreed that China spread virus purposefully

High

Maftei and Holman [34]

Romania

Cross-sectional

Convenience

N = 245, general population,

Mean age = NR

% Female = 78.4

Ethnicity = NR

The 15-item Generic Conspiracist Beliefs Scale (GCB)

GCB: Mean = 2.93 (SD =  ± 0.82)

NR

Moderate

Patsali et al. [35]

Greece

Cross-sectional

Convenience

N = 1535, university students,

Mean age = 22.2

% Female = 71.9

Ethnicity = NR

A 16-items questionnaire for various beliefs in conspiracy theories on a five-point Likert scale

NR

Beliefs in conspiracy theories ranged from 20 to 68%. Less than 50% rejected six out of fifteen beliefs surveyed

Moderate

Pickles et al. [36]

Australia

Longitudinal

Representative

N = 7613, general population,

Mean age = 43.3

% Female = 64.4

Ethnicity = NR

A list of various conspiracy theories (5G, Laboratory development, Intentional spread)

NR

0.6% believed that 5G networks are spreading the virus. 4.2% believed that parcels from China can spread the virus. 12.2% believed that the virus was engineered and released from a Chinese laboratory in Wuhan

Moderate

Prati [37]

Italy

Cross-sectional

Representative

N = 624, general population,

Mean age = 32.3

% Female = 54.0

Ethnicity = NR

Belief about the non-natural origin of the virus based on yes; no; do not know

NR

55% (n = 343) believed that the virus is a laboratory construct and/or the product of purposeful manipulation

Moderate

Romer and Jamieson [8]

USA

Longitudinal

Representative

Wave 1: N = 1050, general population,

Mean age = NR

% Female = 54.4

Wave 2: N = 840, general population,

Mean age = NR

% Female = 55.4

Ethnicity = White, Black, Hispanic

A list of various conspiracy theories (pharmaceutical industry created the virus, laboratory development a biological weapon, the CDC exaggerating the danger to damage the Trump on a 4-point scale)

Wave 1: Average COVID‐19 conspiracy belief:Mean = 1.75 (SD =  ± 0.85)

Wave 2: Average COVID‐19 conspiracy belief: Mean = 1.90 (SD =  ± 1.08)

14.8% believed the pharmaceutical industry created the virus, 28.3% believed the Chinese government created the virus as a bioweapon, 25.3% believed the CDC exaggerating the danger to damage the Trump

Low

Salali and Uysal [38]

UK and Turkey

Cross-sectional

Representative

UK:N = 1088

Mean age = NR

% Female = NR

Turkey: N = 3936

Mean age = NR

% Female = NR

Ethnicity = NR

Beliefs on the origin of the virus (natural/artificial/not sure)

NR

More participants in the UK believed in the natural origin of the virus (54% in Turkey, 63% in the UK, n = 5024, χ2 = 24.6, p < 0.001), and 18% in Turkey and 12% in the UK thought the origin to be artificial, i.e., human made

Low

Sallam et al. [40]

Jordan

Cross-sectional

Convenience

N = 1540, University students,

Mean age = 22.0

% Female = 74.4

Ethnicity = most were Jordanians

On question as follows: “Do you think the COVID-19 pandemic is part of a global conspiracy theory?” (no/yes/maybe)

NR

16.4% (n = 253) of the participants stated that they believe in the role of conspiracy in the origin of the disease, and those who answered maybe represented 49.9% (n = 769) of the study population

Low

Sutton and Douglas [41]

UK

Cross-sectional

Convenience

N = 748, general population

Mean age = 30.7

% Female = 67.6

Ethnicity = White, Black, Asian, mixed race

Freeman (2020) conspiracy scale on three conspiracy beliefs on a five-point (N = 251)

Five-point conspiracy balanced scale on three conspiracy beliefs (N = 251)

Nine-point conspiracy balanced scale on three conspiracy beliefs (N = 246)

NR

Freeman scale: 2% believed that Jews have created the virus for financial gain. 2.8% believed that Muslims are spreading the virus as an attack on Western values, and 31.9% believed that coronavirus is a bioweapon developed by China

Five-point balanced scale: 0.4% believed that Jews have created the virus for financial gain. 1.6% believed that Muslims are spreading the virus as an attack on Western values, and 8.8% believed that coronavirus is a bioweapon developed by China

Nine-point balanced scale: 0.8% believed that Jews have created the virus for financial gain. 0.8% believed that Muslims are spreading the virus as an attack on Western values, and 10.6% believed that coronavirus is a bioweapon developed by China

Low

Teovanović et al. [42]

Serbia

Cross-sectional

Convenience

N = 407, general population,

Mean age = 34.9

% Female = 76.9

Ethnicity = NR

A 13-items questionnaire for various beliefs in conspiracy theories (e.g., 5G) on a five-point Likert scale

Average COVID‐19 conspiracy belief: Mean = 2.25 (SD =  ± 0.79)

NR

Low

Sallam et al. [43]

Jordan, Kuwait and other Arab countries

Cross-sectional

Convenience

N = 3414, general population,

Mean age = 31.0

% Female = 76.0

Ethnicity = Jordan, Kuwait, Saudi Arabia, Others

An 8-items questionnaire that assessed belief in conspiracy about COVID-19’s origin

NR

59.5% believed that COVID-19 is a man-made virus (n = 2031). 40% believed that COVID-19 is a man-made disease made to force everyone to get the vaccine (n = 1376), and 27.7% believed that the COVID-19 vaccine is a way to implant microchips into people to control them (n = 947)

Moderate

Sallam et al. [44]

Jordan

Cross-sectional

Convenience

N = 3150, general population,

Mean age = 31.0

% Female = 76.0

Ethnicity = Jordans and non-Jordans

A list of various conspiracy theories (part of a global conspiracy, a biological warfare, 5G, spiritual divine test or trial)

NR

47.9% believed that COVID-19 is part of a global conspiracy (n = 1501). 57.0% believed that COVID-19 is part of a biological warfare (n = 1778). 21.0% believed that 5G networks have a role in COVID-19 spread (n = 641). 82.7% that COVID-19 pandemic is a divine spiritual test (n = 2595)

Moderate

Jutzi et al. [47]

USA

Cross-sectional

Convenience

Study 2 only*: N = 348, general population,

Mean age = 37.7

% Female = 40.8

Ethnicity = Americans

A list of two conspiracy theories (a biological warfare, laboratory accident) on a five-point Likert scale

Average COVID‐19 conspiracy belief: Mean = 3.21 (SD =  ± 0.96)

NR

Moderate

Lobato et al. [50]

USA

Cross-sectional

Representative

N = 296, general population,

Mean age = 39.5

% Female = 36.2

Ethnicity = Americans

A list of various conspiracy theories (virus is a chimera Donald Trump, a biological warfare 5G) ranged from scores of 0 to 100

Average COVID‐19 conspiracy belief: Mean = 40.9 (SD =  ± 28.47)

NR

Moderate

Oleksy et al. [51]

Poland

Cross-sectional

Convenience

Study 1: N = 1046, general population,

Mean age = 44.1

% Female = 49.9

Ethnicity = NR

Study 2: N = 1680, general population,

Mean age = 26.2

% Female = 74.0

Ethnicity = NR

Studies 1 & 2: A two items questionnaire for general and government-related conspiracies

Study 1: Average COVID‐19 general conspiracy belief: Mean = 4.33 (SD =  ± 1.38)

Average COVID‐19 government-related conspiracies: Mean = 4.39 (SD =  ± 1.66)

Study 2: Average COVID‐19 general conspiracy belief: Mean = 3.76 (SD =  ± 1.44)

Average COVID‐19 government-related conspiracies: Mean = 3.48 (SD =  ± 1.47)

NR

Low