Respondents’ characteristics and the differences in the intention among subgroups
A total of 552 valid responses had been received. As shown in Table 1, the majority of the respondents aged between 25 and 54 years old (n = 439, 79.5%); more females (n = 328, 59.4%) than males (n = 224, 40.6%); more residents (n = 413, 74.8%) than non-residents (n = 123, 22,3%); more than four-fifths (n = 487, 88%) had a bachelor degree or above. In general, the participants were broadly representative of the population in Macao in terms of age and types of residency, but the proportion of female and people having higher levels of education were higher than intended.
Intention to receive COVID-19 vaccination
Overall, 334 or 62.3% of the respondents indicated their intention to receive COVID-19 vaccination, while 106 (19.2%) of the respondents were hesitant and 102 (18.5%) of respondents did not want to get vaccinated. Among respondents where were Macao residents, the percentages of positive, uncertain, and negative responses were 58.4%, 21.3% and 20.3% respectively. Among the subgroups, people aged 55–64 years old, being male, non-residents studying in Macao, being married or single, having a Master degree or above, living alone and expected to have frequent travel in and out of Macau at least once a day had higher intention to get COVID-19 vaccination (Fig. 2). According to the Pearson Chi-square test results (Table 1), statistically significant differences in the intention were observed among the subgroups of age, gender, residency types, education level, parental status and having plans to travel in and out of Macao.
Respondents’ perception about the measurements
Descriptive statistics for items assessing factors related to intention are reported in Table 2. The results of Spearman's rho suggested that each of the items was significantly associated with respondents’ level of intention to receive COVID-19 vaccination.
Threat appraisal - Respondents rated severity (mean = 3.82 ± 1.47) higher than susceptibility (mean = 2.49 ± 1.24). While 67% of respondents believed that COVID-19 can be a life-threatening illness, only 19% believed that the risk for them to catch COVID-19 was high. Regarding maladaptive responses, respondents rated the money they had to spend on COVID-19 vaccination the least concern (mean = 1.72 ± 1.10), followed by the time needed to get vaccinated (mean = 2.04 ± 1.17) and then worries about the vaccine safety (mean = 2.63 ± 1.35).
Coping appraisal - Respondents rated highly their self-efficacy in terms of their ability to register for COVID-19 vaccination (mean = 4.41 ± 1.02), make appropriate arrangements (mean = 4.14 ± 1.22), their level of confidence (mean = 4.12 ± 1.08), and the information they need to make the decision about vaccination (mean = 4.01 ± 1.14). In comparison, their ratings on the response-efficacy was relatively lower regarding the effectiveness of the vaccine in reducing the severity of symptoms (mean = 3.76 ± 1.17), the risks of death (mean = 3.72 ± 1.20), and the number of symptoms (mean = 3.68 ± 1.22) in case of infection. More than one-third of the respondents believed that it would be likely for them to experience unbearable side effects after COVID-19 vaccination.
Social attitudes and social norms - Comparatively, the respondents recognized the impact of COVID-19 vaccination on preventing the diffusion of COVID-19 in the community (mean = 4.09 ± 1.06) higher than the impact on reducing the risk of their family contracting COVID-19 (mean = 3.88 ± 1.14), with the proportion of respondents indicating positive responses differing by nearly 10%. In terms of social norms, 68% of the respondents considered consider getting COVID-19 vaccination a social responsibility and the rating was reasonably high (mean = 3.99 ± 1.17). While 76% indicated that people they knew had already received COVID-19 vaccination, only 59% of them believed that they were expected to get COVID-19 vaccination by the people they knew.
Information seeking behavior - Only half of the respondents indicated that they had actively sought information about COVID-19 vaccination. In terms of the source of information about COVID-19 that they relied on, the government (mean = 3.68 ± 1.27) and online sources (mean = 3.68 ± 1.15) were rated the highest, followed by healthcare professional (mean = 3.19 ± 1.37) and family and friends (mean = 2.73 ± 1.27). It is worth noting that only 42% of the respondents relied on healthcare professionals for COVID-19 vaccination information, and 17% of the respondents did not rely on the information provided by the government.
Facilitating factors - When asked which facilitating factors might increase their intention to receive COVID19 vaccination, the respondents rated loosening of travel restrictions as a result of COVID-19 vaccination the highest (mean = 3.91 ± 1.30), followed by knowing people whom they knew having done so (mean = 3.42 ± 1.35) and a rewarding system involving time off from work (mean = 3.37 ± 1.49). The rating given to financial incentive was the lowest (mean = 3.07 ± 1.52).
Results of multiple linear regression
All factors found to be significantly associated with intention in Tables 1 and 2 were analyzed as the independent variables, and the intention as the dependent variable. Table 3 shows the results of multiple linear regression that analyzed the relationship between intention to receive COVID-19 vaccination and the independent variables. In Model 1, the independent variables comprised only the control variables (i.e. demographic variable shown to have statistically significant correlation with intention as shown in Table 1), which only explained 11.0 % of the variance in intention to receive COVID-19 vaccination. In Model 2, the independent variables comprised only the PMT factors and the control variables. A total of 45.8 % of the variance in intention to receive COVID-19 vaccination can be explained by Model 2. In Model 3, the independent variable comprised all the PMT factors, other factors and the control variables. Compared to previous models, Model 3 performed best at explaining the intention to receive COVID-19 vaccination by being able to explain 57.9 % of the variance in intention to receive COVID-19 vaccination.
In Model 3, in addition to age, 8 items from 7 constructs were shown to be predictors of intention, including 5 positive predictors and 3 negative predictors. In the order of the strongest influence, the positive predictors were: (1) Self-efficacy - “I am able to make arrangement to get COVID-19 vaccination” (β = 0.333, P < 0.001); (2) Social norm - “I consider getting COVID-19 vaccination a social responsibility” (β = 0.326, P < 0.001); (3) Facilitating factor - “I might have a stronger intention to take COVID-19 vaccination if there is a rewarding system such as time off from work” (β = 0.169, P < 0.001); (4) Social norm - “Most people I know would expect me to get COVID-19 vaccination” (β = 0.114, P = 0.000); and (5) Perceived susceptibility - “The risk for me to catch COVID-19 is high” (β = 0.076, P < 0.05). Negative predictors were: (1) “It is likely that I will have serious side-effects that I cannot bear from COVID-19 vaccination” in response cost (β = -0.124, P < 0.001); (2) “If I do not get a COVID-19 vaccination, I will not have to worry about the safety of the vaccine” in maladaptive response reward (β = -0.082, P < 0.05); and (3) “I rely on online sources (such as internet, social media) for accurate information about COVID-19 vaccination” in information seeking behavior (β = -0.065, P < 0.05).