COVID-19 vaccination hesitancy in Italian healthcare workers: a systematic review and meta-analysis

ABSTRACT

Introduction

As for other vaccines, vaccination hesitancy may be a determining factor in the success (or otherwise) of the COVID-19 immunization campaign in healthcare workers (HCWs).

Areas covered

To estimate the proportion of HCWs in Italy who expressed COVID-19 vaccine hesitancy, we conducted a systematic review of the relevant literature and a meta-analysis. Determinants of vaccine compliance and options suggested by these studies to address vaccine hesitancy among HCWs were also analyzed. Seventeen studies were included in the meta-analysis and systematic review, selected from scientific articles available in the MEDLINE/PubMed, Google Scholar and Scopus databases between 1 January 2020 and 25 January 2022. The vaccine hesitancy rate among HCWs was 13.1% (95%CI: 6.9–20.9%). The vaccine hesitancy rate among HCWs investigated before and during the vaccination campaign was 18.2% (95%CI = 12.8–24.2%) and 8.9% (95%CI = 3.4–16.6%), respectively. That main reasons for vaccine hesitation were lack of information about vaccination, opinion that the vaccine is unsafe, and fear of adverse events.

Expert opinion

Despite strategies to achieve a greater willingness to immunize in this category, mandatory vaccination appears to be one of the most important measures that can guarantee the protection of HCWs and the patients they care for.

KEYWORDS:

• Healthcare workers
• vaccine compliance
• COVID-19
• SARS-CoV-2
• nosocomial infection
• mandatory vaccination

1. Introduction

COVID-19, the infectious disease caused by the novel coronavirus SARS-CoV-2, was declared a pandemic in early 2020, having reached global proportions [1]. To deal with the COVID-19 pandemic, a mass vaccination campaign was launched in European countries on 27 December 2020 [2]. In Italy, the government opted to prioritize vaccination of healthcare workers (HCWs) (contextually to frail patients), a decision in line with the recommendations of the Center for Disease Control and Prevention (CDC) [3]. By providing critical care to patients who are or may be infected with SARS-CoV-2, HCWs are at high risk for exposure to the virus and thus the development of COVID-19; furthermore, vaccinating HCWs safeguards healthcare capacity [2].

As with other vaccines, vaccine hesitancy can be a determining factor in the success (or otherwise) of the COVID-19 immunization campaign. In fact, in 2019, the World Health Organization (WHO) listed vaccine hesitancy as a major health threat that year [4]. Indeed, a 2022 narrative review [5] COVID-19 vaccine hesitancy rates in 42/114 countries/territories worldwide ranged from 13% to 59%; this phenomenon appeared more pronounced in Africa, Europe, and Central Asia. Today, vaccine hesitancy is still a challenging health threat as it can compromise the effectiveness of COVID-19 vaccination in the general population and subgroups, including health personnel.

Vaccination hesitancy among Italian HCWs is a topic already investigated in the literature; indeed, insufficient vaccination coverage in Italian health personnel is reported, considering other vaccine-preventable diseases recommended for the category [6–8]. Factors explaining suboptimal vaccination attitudes among HCWs [6–9] include misinformation, loss of confidence, fear of adverse effects, absence of educational campaigns, inaccurate risk perception, unknown or uncertain vaccination status and difficulties in accessing vaccination in the workplace.

To estimate the proportion of HCWs expressing COVID-19 vaccine hesitancy in Italy, we conducted a systematic review of the relevant literature and a meta-analysis. Determinants of vaccine compliance and options suggested by these studies to deal with vaccine hesitation among HCWs were also analyzed.

2. Methods

2.1. Search strategy and selection criteria

The Scopus, MEDLINE/PubMed and Google Scholar databases (up to page 5) were systematically searched. Research articles, brief reports, reviews and meta-analyses published between 1 January 2019 and 25 January 2022 were included in our search. The following terms were used for the search strategy: (adherence OR hesitancy OR compliance OR attitude) AND (covid* OR SARS-CoV-2) AND (vaccin* OR immun*) AND (healthcare workers OR health personnel OR physician OR nurse OR doctor OR residents OR students) AND (Italy). Studies in English or Italian with full text were included. Abstracts without full text, letters to the editor not reporting original data, articles not reporting epidemiological data (editorials, commentaries, etc.) and all studies focusing on issues unrelated to the purpose of this review (vaccine knowledge, adverse vaccine reactions, etc.) were excluded. When necessary, study authors were contacted for additional information. References of all articles were reviewed for further study. The list of papers was independently screened by title and/or abstract by two reviewers who applied the predefined inclusion/exclusion criteria. Discrepancies were recorded and resolved by consensus.

Extracted data included year, sample size, number of hesitant HCWs, professional category, area of questionnaire administration, timing of the investigation (before or during the COVID-19 vaccination campaign), potential determinants of vaccine hesitancy, and options for managing hesitant HCWs.

2.2. Quality assessment

The quality of selected studies was assessed according to the STROBE checklist, which includes 22 methodological questions [10]. Studies assessed according to STROBE had a minimum and maximum possible score of 0 and 44, respectively, and were classified as low quality (<15.5), moderate quality (15.5–29.5) or high quality (30–44).

The risk of bias for each study was independently assessed by two researchers. Discrepancies were recorded and resolved by consensus.

2.3. Pooled analysis

Three different meta-analysis groups were performed: the first included all HCWs, the second compared hesitancy according to different times of survey administration (before the vaccination campaign [1 February 2020–26 December 2020] vs. during the vaccination campaign [from 27 December 2020]) and the third by job category (HCWs, including residents vs. Medical School students). Sub-analysis by study quality was not possible because all studies were of high quality.

The pooled proportion in the meta-analysis was calculated using the Freeman-Tukey double arcsine transformation to stabilize variances, and the DerSimonian-Laird weights for random effects models, with the estimate of heterogeneity obtained from the inverse-variance fixed-effects model. The pooled prevalence and the associated 95% Wald confidence interval were plotted, and a forest plot was drawn. The I² statistic was calculated as a measure of the proportion of the overall variance attributable to heterogeneity between studies rather than to chance. Heterogeneity between studies in different groups was also assessed. A p-value<0.05 was considered to indicate statistical significance of the heterogeneity.

A sensitivity analysis was conducted to evaluate stability; among the studies included in this systematic review, one study at a time was excluded, and the conclusion subsequently based on the others was then reevaluated to avoid severe distortions.

Statistical analysis was conducted using STATA MP17.

Strategies to increase vaccination compliance among HCWs and suggested strategies to address vaccine hesitancy were collected from all available studies and their respective findings were compared, with particular attention to the evidence presented in several of the included papers.

3. Results

3.1. Identification of relevant studies

The flow-chart, constructed following the PRISMA guidance [11] (Figure 1), shows the process of article selection. According to the aforementioned inclusion criteria, 13 articles were identified in Google Scholar, 9 in Scopus, and 15 in MEDLINE/PubMed. After exclusion of duplicate articles in the two databases, there were 19 eligible studies [12–30]. Of these, one [29] was excluded because it evaluated the same phenomenon in a more recent, comprehensive article already included in the meta-analysis and another [30] because additional information was requested from the authors but they did not respond. Thus, overall, 17 studies were eligible [12–28], of which 14 were quantitative [12–25] and three were qualitative [26–28] (Table 1). The remaining 94 studies did not match the inclusion criteria [27–114].

Figure 1. Flow-chart of the bibliographic research.

Table 1. Characteristics of the selected studies included in meta-analysis and systematic review.

First author	Year	Quality	Hesitant HCWs (n)	Total sample	Study period	Italian region	Timing	Population	Evaluation of hesitancy
Quantitative study
Papini F [11]	2022	high	144	2,137	2021	Italy	during	HCW	Respondents were classified as “hesitant” if they selected one of the following answers to the question “If you think you are not vaccinating yourself against COVID-19, can you indicate the reasons among those listed?”: “Because the COVID-19 vaccine had too short a period of testing and control,” “I am afraid of side effects,” “I prefer to wait until more people have been vaccinated, or to wait until next year,” “I doubt it is effective,” “COVID-19 is not a serious disease/the symptoms are generally mild at least in my age group,” “It is preferable to develop physiological immunity (after exposure to the disease)” or “Serious side effects due to the COVID-19 vaccine are kept under wraps.” Furthermore, a participant was considered vaccine hesitant if he or she answered No or Don’t Know to one of the following proposals: “Would you recommend the COVID-19 vaccine to your patients?” or “Would you recommend the COVID-19 vaccine to your family members?.”
Baccolini V [12]	2021	high	297	1,543	2021	Lazio	during	stu	Investigation on vaccination intention (ion a scale from 0 [not at all] to 10 [definitely], how likely is that you’ll get a COVID-19 vaccine?)
Belingheri M [13]	2021	high	81	422	2020	Lombardia	before	stu	Intention to get the COVID-19 vaccine (YES/NO)
Belingheri M [14]	2021	high	75	421	2021	Lombardia	during	dentists	Intention to get the COVID-19 vaccine (YES/NO)
Di Gennaro F [15]	2021	high	568	1,723	2020	social media	before	HCW, res	Attitude toward vaccines recommendations
Di Giuseppe G [16]	2021	high	150	779	2020	Campania	before	HCW	Willingness to receive a vaccine against COVID-19 (YES/NO)
Di Valerio Z [17]	2021	high	119	10,898	2021	social media	during	HCW, stu	Attitude toward COVID-19 vaccination
Forgeschi G [18]	2021	high	48	345	2021	Tuscany	during	hcws	For people who had not been vaccinated, they were asked the reason for it, by choosing among the following options: unavailability in booking for the vaccine, lack of confidence in the efficacy of the vaccine, presence of contraindications to vaccination, previous contagion, concern about long-term effects.
Gallè F [19]	2021	high	79	1,639	2021	Lazio, Campania, Puglia	during	stu	Willingness to receive a vaccine against COVID-19 (YES/NO)
Ledda C [20]	2021	high	196	787	2020	Sicily	before	HCW	Attitudes about vaccine preventable diseases
Pastorino R [21]	2021	high	20	274	2020	Lazio	before	stu	Willingness to receive a vaccine against COVID-19 (YES/NO)
Riccò M [22]	2021	high	11	166	2021	social media	during	HCW	Trust in COVID-19 vaccine
Scardina G [23]	2021	high	1214	6,323	2020	Tuscany	before	HCW, res	COVID-19 vaccination attitude and intention to get the vaccine
Trabucco Aurilio M [24]	2021	high	45	531	2020	Lazio, Molise	before	nu	Participants were asked to indicate (1) whether they had accepted or intended to accept COVID-19 vaccination (“intend/not intend to accept” or “undecided”)
Qualitative study
Vinceti SR [25]	2021	high	-	-	-	-	-	-
Craxì L [26]	2021	high	-	-	-	-	-	-
Frati P [27]	2021	high	-	-	-	-	-	-

HCW = healthcare worker; phy = physician; nu = nurse; oth = other HCW; res = medical resident; stu = students

3.2. Quality assessment

The STROBE checklist was applied appropriately to the included studies, and all were determined to be of high quality (Table 1).

3.3. Pooled analysis

According to our meta-analysis, the prevalence of vaccine hesitancy among HCWs was 13.1% (95%CI: 6.9–20.9%), in accordance with an I² of 99.6% and a p-value for the heterogeneity test of <0.0001. In a comparison of vaccine hesitancy according to different times of survey administration (before vs. during the vaccination campaign), the prevalence of vaccine hesitancy among HCWs investigated before and during the vaccination campaign was 18.2% (95%CI = 12.8–24.2%; I² = 97.7%; p < 0.0001) and 8.9% (95%CI = 3.4–16.6%; I² = 99.4%; p < 0.0001), respectively, according to a p value in the test of heterogeneity between sub-groups of 0.052 (Figure 2).

Figure 2. Forest plot of the pooled prevalence of vaccine hesitancy as determined by the different timing of survey administration (before vs. during the vaccination campaign).

In a sub-analysis of vaccination hesitancy according to job category, the prevalence was 13.6% (95%CI = 5.8–24.1%; I² = 99.7%; p < 0.0001) for HCWs and 9.5% (95%CI = 3.4–18.1%; I² = 98.3%; p < 0.0001) for students, according to a p-value of 0.491 in the test of heterogeneity between sub-groups. Sub-analysis according to the different time of survey administration (before vs. during the vaccination campaign) is described in Figure 3.

Figure 3. Forest plot of the pooled prevalence of vaccine hesitancy, by job category (HCWs, including residents vs. Medical School students) and as time of survey administration (before vs. during the vaccination campaign).

Sensitivity analysis showed no severe distortions from any specific study.

3.4. Determinants of vaccination compliance and suggested strategies to address vaccination hesitancy

All studies concluded that vaccination hesitation is a crucial issue in the management of COVID-19 pandemic. Many determinants of hesitancy have been investigated; most studies have reported that the main reasons are lack of information about vaccination, opinion that the vaccine is unsafe, and fear of adverse events [14–17,21,23], with the exception of Trabucco Aurilio M et al. [25] who did not identify safety concerns in their sample of nurses. Moreover, the role of pharmaceutical companies in influencing vaccine policy decisions and the uncertainty associated with the rapid development process of COVID-19 vaccines [15–17,23] were also determinants of the hesitation. Minor factors of a negative attitude toward the vaccine were fear of ineffectiveness due to virus mutations [23], disagreement with vaccinations in general, the opinion that COVID-19 is not a threatening disease [15] and lower trust in adenoviral vaccines amid reports of its association with thromboembolic events [23]. A history of infection prior to vaccination [13,14,20,25] and a diagnosis among family members and friends [15] did not appear to influence vaccination compliance nor hesitancy. Concern about COVID-19 disease-related risk is a determinant of better attitude, as reported by three studies [12,16,17,23], whereas for Bellingheri M et al. [14] it did not influence willingness. HCWs reported that the safety and protection of themselves and their patients was one of the main reasons for vaccination uptake [17,21]; it was particularly important for individuals with comorbidities [21], even though, as reported by Bellingheri M et al. [15], some HCWs reported immune disorders and severe allergies as additional reasons for avoiding receiving COVID-19 vaccination. HCWs with higher education degree and information from scientific sources were associated with better acceptance [17,20,21]; indeed, HCWs who used mass media or the Internet as their main source of information did not have significant benefit in their willingness to accept the COVID-19 vaccine in the future [17]. Overall, the main determinant of vaccination compliance was having received previous vaccination, especially the anti-influenza vaccine [12,14–16,18,22,25].

Regarding age, higher levels of compliance have been reported in young HCWs [18,21], even if Ledda C et al. [21] reported low hesitancy in subjects older than 51 years. More discussed is the different approach to immunization between the sexes, with four studies [12,17,20,21] reporting better compliance in males and two [13,25] in females.

Physicians seemed to report less hesitancy, compared with other healthcare professionals [12,17,24]; in particular, physicians employed in pediatrics, oncology, and geriatrics seemed more prone to have an accepting attitude toward vaccines (probably because of the characteristics of their patients) [18]. In general, having worked in a COVID-19 ward increased compliance with vaccination [18,24]. Furthermore, as reported by Riccò M et al. [23], health personnel identified vaccines as instrumental in coping with a series of significant issues that emerged during the first stage of the pandemic, i.e. the limited reliability of most Personal Protective Equipment (PPE), the limited utility of non-pharmacological interventions in healthcare settings, inappropriate risk perceptions among many healthcare professionals and awareness of the difficulty of tracing and tracking HCWs. Finally, as reported by Baccolini V et al. [13], hesitancy to the COVID-19 vaccine has changed over time and in relation to several factors, including confidence in the efficacy and safety of the vaccine, perception of disease risk and education level. By identifying the factors that hinder vaccination, it will be possible to plan vaccination campaigns that can lead to overcome resistance on the part of health personnel [19].

Regarding strategies to manage vaccine hesitancy among HCWs, many authors have proposed the urge to better educate health personnel and fight fake news [12–15,17,18,25,28]; in fact, improving vaccine acceptance and information in HCWs can be doubly effective in the struggle against the pandemic, as they are employed on the frontlines and can be decisive in influencing the general population [18].

On the other hand, the presence of a non-negligible number of HCWs who are opposed or undecided may compromise hospital health policies and jeopardize the safety of the fragile patients with whom they come into contact [25], so several recent works have advocated mandatory vaccination, in response to a pressing social need to protect individual and public health, and above all as a defense of vulnerable subjects or patients [12,14,23,26,28]. Health personnel themselves have expressed fair adherence to mandatory vaccination for health professional [27]. In fact, knowledge of recommended vaccinations and acceptance rates of mandatory vaccinations increased significantly among HCWs during the COVID-19 pandemic in Italy [21].

4. Conclusion

Our meta-analysis estimated vaccine hesitancy among HCWs in Italy to be 13% (95%CI = 7–21%), lower than the value reported in a 2021 scoping review (23%) [114] that investigated vaccine hesitancy among HCWs worldwide. Moreover, our study showed that vaccine hesitancy decreased in the study set during the vaccination campaign, compared with those set before it (9% vs 18%); probably, evidence of vaccine safety, increased incidence of COVID-19 cases, and the example of other colleagues increased vaccine compliance, as also reported by Baccolini V et al. [13].

Considering the occupational category, students appear to be slightly less hesitant than HCWs (9% vs. 14%). This difference is more pronounced in the subjects interviewed before the start of the vaccination campaign, with students showing a percentage of hesitancy equal to 14%, whereas for HCWs this was 20%; on the other hand, the subjects interviewed during the vaccination campaign expressed the same value of vaccination hesitancy (8%). Considering that, especially during the first lockdown, academic and internship activities were suspended [115], Medical School students should have had less ‘on-the-ground’ awareness of COVID-related issues. On the contrary, HCWs experienced the concerns of nosocomial management, ward reorganization, awareness of being at risk for infection, awareness of the complications of COVID-19. Nevertheless, the data showed that despite this, HCWs were more hesitant than students of Medical School.

The systematic review showed the main determinants of vaccination hesitancy; lack of information about the vaccination, the opinion that the vaccine is not safe, and fear of adverse events are known determinants of vaccination refusal in the scientific literature; indeed, these data confirmed evidence already reported in the literature for other vaccinations [6–8]. On the other hand, the role of pharmaceutical companies in influencing vaccination policy decisions and the incertitude associated with the rapid development process of COVID-19 as determinants of hesitation are pathognomonic of COVID-19 vaccination compared with other vaccines; such evidence, confirmed by other studies in the literature [116], should be surprising considering that HCWs should be familiar with the mechanism of drug development and marketing.

History of disease or experience with it among family members and friends did not influence opinion about immunization, whereas fear of COVID-19 complications and the safety and protection of self and patients seemed to increase willingness to vaccinate. Higher education and scientific sources have played a fundamental role in the attitude of HCWs; indeed, it must be considered that older Italian HCWs (including nurses and auxiliary staff) often do not have a master degree. Trust in the scientific community has already been identified has a major determinant of vaccination compliance in the general population [117,118] and thus, also for health care workers has a main role. Then again, the role of social media and the internet in spreading misinformation, and thereby facilitating vaccine distrust, is well known [119,120].

In any case, one of the main determinants of vaccination adherence was having received a previous vaccination, particularly anti-influenza vaccine; this evidence had already been reported in the literature for other vaccinations [71,121], but it seems to be valid for COVID-19 vaccination as well [114].

The relationship between age and willingness to vaccinate is already reported in the literature, especially regarding other vaccinations [8]. Our systematic review did not clearly highlight the attitude to COVID-19 vaccination of Italian HCWs considering age class, but a scoping review in 2021 [114] showed that older health personnel were more likely to accept COVID-19 vaccines, worldwide. Anyway, we can consider the professional category as a proxy for the age group and therefore our meta-analysis showed a better compliance in students (hence young subjects) especially before the beginning of the vaccination campaign; more studies are needed to evaluate this topic for Italian HCWs. The same issue is evidenced with regard to sex, with the scoping review mentioned above suggesting better compliance in male subjects [114].

Regarding the professional category, physicians seem to be more prone to vaccination and this evidence is confirmed in the literature [8,122]; moreover, this topic has been well studied with regard to other vaccinations and many studies in the literature agree that a higher level of education and degree are associated with a better compliance to vaccination [123,124].

Having worked in a COVID-19 ward is another determinant of vaccination readiness, probably because those HCWs have seen COVID complications up close; furthermore, Italian HCWs at the beginning of the pandemic considered the availability of PPE inadequate [125] and so, as also reported by Bianchi FP et al. [126], the vaccine may be considered by HCWs as a type of PPE.

Education of HCWs and fighting fake news to combat vaccination hesitancy among HCWs are topics investigated in many studies in the literature [127–134]; despite this, our systemic review revealed that mandatory anti-COVID-19 was desirable for both the authors of the studies and the interviewed HCWs themselves. Indeed, on 1 April 2021, the Italian Government issued the Decree Law no. 44 establishing compulsory COVID-19 vaccination for HCWs [26].

The main limitation of this meta-analysis was the high heterogeneity across studies, as indicated by the I² values. The reason of this high heterogeneity may be multiple. Indeed, one of the reasons is that the phenomenon was investigated among the HCWs of many Italian regions; moreover, the author investigated the ‘vaccine hesitancy’ using different definitions as reported in Table 1. Furthermore, the performed sensitivity analyses did not show an improving of heterogeneity values across studies. Anyway, the use of a random-effects analysis in statistical analysis minimized this bias; therefore, this does not appear to be a critical issue. It was also not possible to stratify susceptible HCWs on the basis of their previous illness, gender, age group, and job mansion. Another argument is that most surveys were administered online or on social media and thus it is possible that HCWs answered more than one questionnaire; this potential bias is unfortunately not detectable or correctable. However, a strength of our review and meta-analysis was the large sample size resulting from the collation of selected papers, which improved statistical analysis and provided a better view of COVID-19 vaccine hesitancy among Italian HCWs. In addition, all studies were published from 2021, so this view is up-to-date and reliable. Finally, the meta-analysis showed a comparison of vaccine hesitancy before and during the vaccination campaign, not previously reported in the literature.

5. Expert opinion

Our study highlighted a moderate proportion of healthcare workers expressing hesitation in vaccination and the main determinants of vaccination compliance. Despite strategies to achieve greater immunization willingness in this category, a few months after the start of the vaccination campaign the Italian government opted for mandatory vaccination. This strategy, which has already proved successful with regard to other categories of the population [135], appears to be the only one capable of guaranteeing the protection of HCWs and the patients they care for.

Vaccination resistance by healthcare professionals is a globally studied phenomenon [31,61,74,114], although it may seem counterintuitive. Therefore, even though education and training programs are essential, especially for HCWs with lower levels of education, they do not seem to be sufficient [104]. Emergency situations require drastic measures such as mandatory vaccination; the obligation introduced in Italy, in fact, is based on fitness for work assessed by occupational health physicians, with suspension of salary until immunization [28]. The impact of this law on immunization status has led to an increase in vaccination coverage with the elimination of the last resistance in health personnel. Paradoxically, however, hundreds of HCWs still reject the vaccine.

Vaccination of HCWs, especially in a pandemic context, is a vital measure from a public health perspective; in fact, it guarantees the protection of operators and patients (especially the most fragile ones), allows the safety of nosocomial structures and reduces absenteeism due to illness, ensuring a smooth service to citizens. Furthermore, HCWs are among the most trusted sources of vaccine information and have a direct influence on the vaccination decisions of their patients and social contacts [136]. Indeed, the success of a vaccination campaign largely depends on the penetrance of the message addressed to general population, which takes on an even more strategic value when vaccine candidates suffer from chronic diseases [137,138]. This last point is of crucial importance in the fight against the pandemic and the return to normalcy.

On the other hand, the role of information sources, particularly social media, must also be questioned. Italy has already experienced the risk of vaccine campaign failure due to the uncontrolled dissemination of erroneous information by the media on two separate occasions (Fluad 2014, Vaxveria 2021) [139,140]. Although media content cannot be controlled, it must be taken into account that especially social platforms are the battlefield of Italian no-vax groups that, even if small in number, are very organized and able to circulate false news in a very short time [140]. As reported by Paris C et al. [141], media communication has a dramatic effect on vaccine hesitancy even in HCWs. This is precisely why it is appropriate for public health institutions to organize to ensure proper institutional and scientific communication, especially on social networks.

The presence of figures of high scientific depth on the mass and social media is fundamental in order to disseminate the most up-to-date scientific evidence and inform and educate the population [142]. Scientific community must deal with this issue with a better willingness to communicate even the clinical studies to those people not able to understand the medical information autonomously. Experiences reported in Italy, such as that of the website ‘Vaccinarsi,’ indicate that during the pandemic there was a strong increase in views, concluding that combining disciplines such as health education and digital communication through Information and Communication Technologies (ICT) represents the best strategy to support citizens [75]. At the same time, training experiences of health operators in digital communication and social networks knowledge are reported [143].

Finally, the role of the Italian government should also be discussed. The decision of the obligation in health professionals (and subsequently in the over 50s) should have been explained more clearly and justified from a scientific point of view [67]. Politicians should not be seduced by the vote pool of the no vax and anti-science community, but should rely on scientific evidence and educate the population to data-based decisions.

In conclusion, vaccination hesitancy toward the COVID-19 vaccine among Italian health professionals is an existing phenomenon. In order to achieve a high vaccination coverage, mandatory vaccination was introduced, which resulted in an increase in vaccination uptake with the achievement of very high vaccination coverage. This strategy is successful and has already been tested with the flu vaccine in some Italian regions in previous years [140], with interesting results [144]. Potential susceptibility to vaccine-preventable diseases has been addressed many times by our research team [8,123,145–154]; we must emphasize that even in the time of COVID-19, circulation of microbiological agents in nosocomial facilities is still possible. Therefore, our opinion is that the obligation of vaccination should be deeply considered by policymakers in order to extend to health professionals, especially those working in wards particularly at risk, even for other vaccine-preventable diseases. The effects of this mandatory strategy should be evaluated in terms of cost-efficacy and considering the medical-legal aspects, but at present we believe that it is the fastest solution to solve the problem of vaccination hesitation in healthcare personnel. At the same time, in the medium-long term, complementary strategies to increase vaccination compliance should be put in place, in order to reevaluate the attitude of the HCWs toward vaccination and possibly return to a non-mandatory strategy.

Article highlights

• Vaccine hesitancy can be a determining factor in the success (or otherwise) of the COVID-19 immunization campaign

• Vaccination hesitancy among Italian HCWs is a topic already investigated in the literature

• Insufficient vaccination coverage is reported, considering other vaccine-preventable diseases recommended for the category

• Our study estimated the prevalence of COVID-19 vaccine hesitancy in Italian HCWs (not currently available from institutional data), that was assessed around 13%.

• COVID-19 vaccine hesitancy decreased in the study set during the vaccination campaign, compared with those set before it (9% vs 18%)

• The scenario of management strategies for hesitant individuals is very difficult

• Our results highlight that vaccine hesitancy in healthcare professionals is a genuine public health concern in Italy

• Mandatory vaccination seems to be a winning strategy to deal with low uptake

Author contributions

FPB and ST conceived the study. FPB and PS did the literature research. FPB did the meta-analysis. SL and AM participated in the design of the meta-analysis. NB supervised the meta-analysis. FPB and ST co-drafted the first version of the article.

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Additional information

Funding

This paper was not funded.