Vaccinations are the best way to promote health by reducing morbidity and mortality from infectious diseases. Nevertheless, the usual administration method, by needle puncture, can cause fear and generate a rejection or avoidance of vaccination.

The recorded prevalence of needle-related fear (NF) is highly variable. This is due to the fact that, in general, studies have been carried out in population groups subjected to treatments that require needle administration, as is the case of patients with allergies (e.g., Ferreira et al., 2013, 11%), cancer (e.g., Cox & Fallowfield, 2007, 41%; Harris et al., 2009, 16.9%; Kettwich et al., 2007, 64%), diabetes (e.g., Cemeroglu et al., 2015, 22%; Howe et al., 2011, 9.5-40.9%), dialysis (Mulder et al., 2013, 25.9-26.7%), multiple sclerosis (Turner et al., 2009, 41.4%) or dental interventions (e.g., Armfield, 2010, 13.8%; Elmore et al., 2014, 42.6%; Milgrom et al., 1997, 4.6%; Taani, 2001, 82.1%). As an example, in a sample of young adult travellers attending a vaccination clinic, 21.7% reported that they were afraid of injections and 8.2% described their fear as excessive (Nir et al., 2003). For this excessive or phobic degree of fear, as an example, prevalences of 11 to 19% have been recorded in children (Majstorovic & Veerkamp, 2004), and 3.5 to 10% in the adult population (Nir et al., 2003). Information from the NF in Spanish population is scarce. A significant study was carried out by Prieto (2011), regarding dental puncture in university students, finding a prevalence of 10.7% to 15.1% of moderate level of anxiety and fear; and from 4.1% to 4.7% of high level of anxiety and fear.

Studies on avoidance of treatment due to NF have also been carried out in specific population groups such as those undergoing dental interventions (e.g., Crawford et al., 2005, 8%; Vika et al., 2006, 11.3%), diabetes (Zambanini et al., 1999, 13.9%), or dialysis (Mulder et al., 2013, 41.2-55.3%). Regarding avoidance of vaccination, the results showed evidence of avoidance of vaccination against influenza (McLenon and Roger, 2019, 8-27% healthcare personnel, and 6-16% adult patients; Wright et al., 2009, 64.1% adult patients), pneumococci (Johnson et al., 2008, 19% adult population), and tetanus (Johnson et al., 2008, 20% adult population; Wright et al., 2009, 30.8% adult patients).

The prevalence of NF, and the avoidance of treatment due to this reason, is influenced by the sociodemographic variables of age and sex. Higher levels of prevalence have been observed in young people and women (e.g., Cox & Fallowfield, 2007; Sokolowski et al., 2010; Wright et al., 2009). In one study carried out in Canada, 63% of children (aged 6-17) reported fear of needles and significant relationships between fear of needles and the female sex, as well as increasing perceived pain intensity during immunizations (Taddio et al., 2012). Everything indicates that NF decreases with age (e.g., Majstorovic & Veerkamp, 2003; Muris et al., 2000). Through meta-regression studies, in studies with samples from Australia, Canada, Egypt, Hungary, India, Italy, Iran, Israel, Saudi Arabia, and Sweden, prevalence data of 20-50% in young people, 20-30% in young adults, and less than 5% in older adults were obtained, observing a decrease of 8.7% per decade (McLenon & Roger, 2019). Concerning sex, Tsao et al. (2006) found that parental anxiety and sensitivity contributed to anxiety and sensitivity in girls but not in boys (aged 8-18). In their turn, McLenon and Roger (2019) recorded a higher mean prevalence in women (1.4 times) than in men, although individual results were heterogeneous, being high in countries such as Saudi Arabia and Israel, but quite low in others like Sweden. In general, the studies refer to children and adolescents. In an Spanish sample, Prieto (2011) did not observe statistically significant differences according to gender.

At the time of this study no references were found on the prevalence of NF among adult citizens who needed vaccination as a result of a pandemic such as COVID-19, which affects the world population and has a high rate of infection and mortality, not being comparable to the cases studied referenced in the bibliography. Therefore, given the expected increase in the number of future pandemics and the possibility that NF has a negative impact on vaccination plans, it is considered necessary to address this knowledge gap.

In parallel to NF, in previous vaccination plans against influenza, measles, or papilloma, it has been observed that vaccine-related conspiracy theories (CTs) were associated with a greater vaccination refusal (e.g., Jolley & Douglas, 2014; Sallam, 2021). These TCs focus primarily on fear of potential vaccine side effects and in hoaxing and mistrusting in the governments, vaccine manufacturers, and healthcare professionals (e.g., Gualda et al., 2019; Roozenbeek et al., 2020; Sallam et al., 2021). Although negative correlations between vaccination TCs and vaccination intention have been repeatedly established (e.g., Jolley & Douglas, 2014; Roozenbeek et al., 2020; Salali & Uysal, 2020), whether there is any relationship between CTs and NF is unknown, specifically, whether people with NF exhibit more reasons, other than their NF, related to CTs to justify vaccination avoidance.

In this context, the present study aims to expand previous research on the relationship between needle-related fear (NF), vaccination fear (VF), vaccination intention (VI), and some commonly used reasons to justify vaccination avoidance in adult Spanish citizens. The hypotheses of the study were that NF (1) will be influenced by demographic variables such as gender and age and will present (2) positive and significative relationships with VF, (3) negative and significative relationship with VI, and also (4) positive and significative relationships with alleged reasons to avoid vaccination (RAV) other than NF.

The sample analysed is large and has allowed the aims of this study to be achieved. In the first place, they allow us to establish prevalences of 5.1% for NF, 40% for VF, and 49.8% for VI. In turn, percentages of 44.8% were obtained for negative beliefs related to the usefulness of vaccines, 44.2% related to their safety, 6% who do not believe in the information on the severity of the disease, 12, 4% who see the interests of pharmaceutical companies behind, and 7.6% who distrust the information provided by the government. In any case, the percentage of people who declare neither for nor against is striking, being indicative of the high percentage of hesitant, especially for VI (23.7%) and for those who doubt the efficacy of the vaccine for controlling the infection (41.8%). The prevalence of 5.1% obtained for NF is within the range of 3.5 to 10% reported by Nir et al. (2003) for the adult population, but it is lower than the 8% reported by Crawford et al. (2005), and 11.3% by Vika et al. (2006). It is also below the 10.7% to 15.1% reported by Prieto (2011) in the Spanish adult population. In any case, these differences may disappear if we take into account that 7.4% declared themselves undecided (perhaps fearful).

The analysis of NF related to sociodemographic variables indicates being a woman (t = -2.68, p < .007), of 20 to 40 years (F = 2.28, p = .044), and without dependents in charge (t = 3.345, p > .001) as risk factors. Being female has previously been described as a risk factor by other researchers (e.g., Cox & Fallowfield, 2007; Sokolowski et al., 2010; Tsao et al., 2006; Wright et al., 2009). But not by Prieto (2011) in a sample of Spanish university students. This divergence was also detected by McLenon and Roger (2019) in their meta-analysis of samples (mostly children and adolescents) from Australia, Canada, Egypt, Hungary, India, Italy, Iran, Israel, Saudi Arabia, and Sweden, observing a higher average prevalence in women compared to men, but with high data in countries such as Saudi Arabia and Israel, and quite low in others such as Sweden. The differences described by these researchers could be related to the specific group analysed. For age, in the present study, the prevalence of NF increases during the third decade of life, after which it begins to decline. Therefore, initially, it could be said that the data obtained in this study differ from those reported by other researchers such as Majstorovic and Veerkamp (2003) or Muris et al. (2000), who indicate that NF decreases with age in the adult population. Also McLenon and Roger (2019), who established a decline of 8.7% per decade. But if we take into account the studies carried out in children and adolescents, we observe that NF is higher in the group of adolescents (e.g., Cox & Fallowfield, 2007; Sokolowski et al., 2010; Wright et al., 2009). So, in a first phase, NF increases with age, confirming obtained results.

The correlation analysis results were in line with hypotheses 2 to 4. NF has weak but significant and positive correlations with VF (rho = .30, p > .001, Γ = .35, D = .23); and weak but significant and negative with VI (rho = -.20, p > .001, Γ = -.28; D = -.17). With respect to RAVs, correlations were significant (p < .001, Γ = .32 to .49, D = .20 to 0.32) and positive but weak (rho = .23 to .35) for all, except for RAV-1 (negative belief in the efficacy of the vaccine for infection control) which present a very poor correlation. The strongest correlations were with RAV-3 (hoax belief about the severity of the infection) and with RAV-4 (mistrust of pharmaceutical companies), followed by RAV-5 (mistrust in government). Contrary to what might be expected, RAV-2 (negative belief in the safety of vaccines and their side effects) shows a lower correlation than RAV-3, RAV-4, or RAV-5, which seems to indicate that NF and its possible causes, such as injection pain, have not been linked to the safety of the vaccine, a fact that is consistent with the etiology of NF.

The hierarchical regression analysis confirms the data found in the correlation analysis. The explained variance of NF on VF and VI is significant (β = .29, t > 14.0, p < .001) but relatively low (8.4% and 3.7% respectively), and highly influenced by sociodemographic variables of gender and dependency, capable of increasing it up to 14.2% and 6.2% respectively. In the same way, the explained variance of NF in RAV2 to RAV-5 is also significant (β = .18 to .28, t > 9.3, p < .001) but relatively low (6.1%, 8.2%, 6.4%, and 3.8% respectively), increasing as consequence of the sociodemographic variable of gender, and less by dependency, at 12.4%, 8.2%, 8.0%, and 4.5% respectively. RAV-1 on the efficacy of the vaccines presented a lower explained variance (2.2%, increased by sociodemographic variables to 5.1%) and a negative relationship.

In conclusion, the results confirm the study hypotheses. NF is influenced by sociodemographic variables of age, gender, and dependency. NF presents significant (although low) relationships with analysed variables, being positive with FV, negative with VI, and positive with RAVs related to negative beliefs about the safety of vaccines, hoax about the severity of the infection, and mistrust of pharmaceutical companies and the government. Only RAV on vaccine effectivity not was confirmed.