Table 3. Significant predictors of COVID-19 vaccine acceptance among HCWs reported in each study.

	Predictors of Vaccine Acceptance
No.	Author/year, country	Reference No.	Variables (Statistically Significant)
			Age group	Sex	Marital Status	Education level	Presence of comorbidities	Flu vaccine	COVID risk/ susceptibility perception	Vaccine perceived benefit	Others
1.	Alobaidi/2022, SA*			Male	Widow/divorced/separated	Higher (MS, PhD)	✔				• Nationality: Non-Saudi • Monthly income: higher (>15K SR)
2.	Arif/2021, SA			Female	Married	Bachelor					• Monthly income: moderate (5K-10K SR) • Vaccine convenience (vaccination method, frequency, distance to vaccination site. etc) • Higher number of vaccinated friends/family members • Belief that vaccine should be mandated by the government
3.	Baghdadi/2021, SA		Middle (30–49 yr)	Female					✔	✔	• Perceived severity of COVID-19 • Belief that all HCWs should be vaccinated against COVID-19 • Work experience: low (<5 yr) • Non-smokers • Having no fear of injections • Perceived lack of barriers to receive the vaccine
4.	Barry/2021, SA			Male	Married			✔	✔	✔	• Working in adult ICU and isolated floors • Source of information: CDC
5.	Elharake/2021, SA		Younger (25–34 yr)	Male							• Nationalities: Non-Saudi
6.	Maqsood/2022, SA			Male						✔	• Nationalities: Non-Saudi
7.	Qattan/2021, SA			Male				✔	✔		• Being a frontline healthcare worker • Believe that COVID19 vaccine should be compulsory
8.	Al Awaidy/2020, Oman			Male						✔	• Recommend COVID-19 to family members • Higher level of knowledge about COVID-19 vaccine • Trust in government • Positive attitude towards COVID-19 vaccine
9.	Khamis/2022, Oman			Male						✔	Belief that vaccine should be mandated
10.	Maraqa/2021, Palestine		Younger	Male				✔	✔		• Physicians • Working in a non-governmental setting • Higher knowledge about COVID-19 • - High income
11.	Rabi/2021, Palestine		Younger								• Higher level of knowledge about COVID-19 vaccine • Perception of the vaccine as safe • Preference of vaccination over natural immunity • No fear of injections • Not influenced by media misrepresentation • COVID-19 might cause or potentiate existing chronic diseases
12.	Kumar/2021, Qatar		26–35 yr	Male	Married			✔	✔	✔	• Higher level of knowledge about COVID-19 and the vaccine • Recommending the vaccine to oneself children
13.	Zammit/2022, Tunisia		≥ 40 yr	Male							• Works in North of Tunisia • Previously infected with COVID-19 • The national and official health websites as the primary source for COVID-19-related information
14.	Albahri/2021, UAE										• Nationality: non-Emirati • Profession: Nurses
15.	AlKetbi/2021, UAE		Older	Male							• Physicians/surgeons • Working in private sector • Nationality: South Asian • Religion
16.	Saddik/2022, UAE			Male				✔	✔		• Positive attitude towardCOVID-19 vaccine • Belief that there are sufficient data about the vaccine • No concern about vaccine side effects
17.	Aloweidi /2021, Jordan				Unmarried				✔	✔	• Medical personnel advice • Social media awareness campaigns • Reading a scientific article about the available vaccines • Trust in vaccine efficacy and safety • National medical studies to prove the efficacy of the vaccines
18.	Lataifeh/2022, Jordan							✔			• Being a physician (vs. nurses) • Registering on COVID-19 vaccine special platform
19.	Qunaibi/2021, multinational		Older	Male				✔
20.	Al-Sanafi/2021, Kuwait			Male		Postgraduate degree					• Being a physician or dentist • Nationality: Kuwaiti • Working in public sector
21.	Nasr/2021, Lebanon							✔	✔		• Moderate or high knowledge level regarding COVID-19 vaccine • fear of COVID-19 disease
22.	Youssef/2022, Lebanon			Male				✔		✔	• Frontline health workers • Concerns about limited accessibility to the vaccine • Concerns about availability of the vaccine. • Receiving reliable and adequate information about vaccine • Recommendation from health authorities and health facilities
23.	Khalis/2021, Morocco										• Being a physician, nurse, or technician • high score of confidence in the information circulating about COVID-19 • high score of perceived severity of COVID-19
24.	Ahmed/2021, Saudi Arabia		• 36 > years	Female			✔
25.	Aldosary/2021, Saudi Arabia										• Higher knowledge score about COVID-19 disease • Higher practice score toward COVID-19 measures
26.	Alhasan/2021, Saudi Arabia*										• Saudi National • Receiving both vaccination doses (1st and 2nd shots) • High knowledge score about delta variant. • High perception score regarding COVID-19 measures (mask, lockdown..) • Believing that the Pfizer-BioNTech BNT162b2 vaccine is effective against Delta variant. • Agreement that mixing/matching vaccines is effective against Delta variant.
27.	Fares/2021, Egypt			Male					✔		Those who took non-compulsory vaccines Those who recommended COVID-19 vaccination to others Those who received advice from their hospitals to get the vaccine Those who showed trust in vaccine producers Those who received sufficient information and trusting the information on COVID-19 vaccine Considering taking vaccine as a community responsibility
28.	Elkhayat/2021, Egypt		Younger people (18–<30)	Male	Single	Higher		✔	✔	✔	Using reliable source of information Urban residence Job category- Doctors Attending awareness sections
29.	El-Sokkary/2021, Egypt		42.5 ± 12.2	Male		Higher			✔	✔	• Monthly income: > 5000 LE • > 10 years of working experience • Using reliable sources of information for vaccines and attending vaccine meetings.
30.	Shehata/2022, Egypt		Youngest group (18–30)	Male	Married	Lower (bachelor’s grade)		✔	✔		• Urban area • Physicians who worked in frontline positions • primary surgical and surgical subspecialty • physicians who had someone they knew diagnosed with COVID-19 and had direct contact with COVID-19 patients • Absence of comorbidities • Obesity • COPD • Non-smoking
31.	Sharaf/2022, Egypt			Male					✔	✔	• Not anxious about Covid-19 at all • never postponed other recommended vaccines • has intentions to travel internationally • responsibility and fear of transmitting the disease to relatives or friends • not concerned about the safety and efficacy of vaccines
32.	Noushad/2021, SA		Oldest group (50 and above)	Male					✔		• updating self on the development of COVID-19 vaccines • opinion about the severity of COVID-19 (increased severity perception) • Greater compliance with COVID-19 preventive guidelines • higher level of anxiety about contracting COVID-19 • Saudi nationals
33.	Hamdan- Mansour /2022, Jordan			Male							• History of COVID-19 infection • Higher level of knowledge and perception about COVID-19 vaccines.

*Evaluated the acceptance of the COVDI-19 vaccine booster dose.