Setting and study design
The Human Research Ethics Committee of the Faculty of Medicine, Ramathibodi Hospital, Mahidol University, COA. MURA2021/1063, approved the study protocol. We conducted a cross-sectional telephone survey about vaccine hesitancy among caregivers of older patients in a geriatric clinic, Ramathibodi hospital which provides a tertiary care for older patients. The hospital database was used to retrieve the names of 318 dependent patients aged 60 and up who visited a geriatric clinic in the past two years. The dependent patients were defined by elderly who had physical and mental dependence and cognitive impairment. Thus, 318 caregivers of the dependent patients who identified themselves as patients' representatives and were responsible for making COVID-19 vaccination decisions for the patients under their care were contacted and asked to take part in this study. All participants, on the other hand, provided verbal informed consent, which was recorded according to the verbal informed consent protocol approved by the Human Research Ethics Committee of the Faculty of Medicine, Ramathibodi Hospital, Mahidol University. We did not obtain written informed consent because we conducted a telephone survey and it was inconvenient for participants to sign written informed consent forms and handle documents during the pandemic. The agreed-upon participants were interviewed by a trained interviewer. The survey was performed over the phone from June 20 to July 25, 2021. The study was conducted according to the Declaration of Helsinki and Good Clinical Practice guidelines. [20, 21]
Questionnaire
The questionnaire used in this study was developed after a review of the literature [22-34] and consensus among the experts including the psychiatrists and geriatricians. The questionnaire was structured into 5 sections, including caregiver sociodemographic data, patient sociodemographic data, medical history, COVID-19 pandemic-related information, and COVID-19 vaccine-related information. A pilot sample (n = 10) was used to improve the language and clarity of expression of the survey items. The pilot sample's data was not used in any subsequent analysis. The final version of the questionnaire required 30-45 minutes to complete on average. The questionnaire was originally developed in the Thai language.
Caregiver sociodemographic characteristics
Participants were asked about their sociodemographic information, including age, gender, marital status, education, relation with patient, employment status, monthly income, income loss due to COVID-19, and vaccination history including influenza, pneumococcal, zoster, and diphtheria-tetanus-pertussis (DTP) vaccines.
Patient sociodemographic characteristics and medical history
The sociodemographic characteristics of the patients were collected similar to the caregivers. In addition, participants were asked to report patients' medical history, including their body mass index (BMI), ambulation, hearing problem, visual problem, history of smoking and alcohol drinking, food and drug allergy, underlying diseases, cognitive complaint, hospitalization in the previous year, and overall health perception.
COVID-19 pandemic-related information
Participants were questioned on their general knowledge about COVID-19, the primary source of information regarding COVID-19, confidence in government and public health agency information about COVID-19, confidence in Thailand's healthcare system's capability to care for COVID-19 patients, measurements from the government to control COVID-19 infection, risk of getting COVID-19 infection, self-perception to develop severe COVID-19 infection and attitude towards social distancing, and intention to get COVID-19 vaccination.
COVID-19 vaccine-related information
Participants were questioned about their hesitations towards administering the COVID-19 vaccine to patients who were under their care. They were asked if they knew people who developed a severe reaction to the COVID-19 vaccine, had an intention to get COVID-19 vaccination, had already received the COVID-19 vaccination, wanted the patients to be vaccinated for COVID-19, and thought the manufacturer of the COVID-19 vaccine influenced their decision to let the patients get vaccinated. Participants were also asked whether they still wanted the patients to get vaccinated if the patients were offered vaccines from the manufacturer they had never expected before. Those who were hesitant to allow their patients to acquire the COVID-19 vaccines were questioned why they were hesitant. Furthermore, every participant was asked why they were willing to immunize the older adults with COVID-19 vaccines.
Statistical analysis
The number and percentage of patients were used to summarize nominal data, such as the presence of underlying disorders. Based on the normality of the distribution, continuous variables, such as age, were summarized as mean, standard deviation (SD). For categorical variables, a Chi-square test or Fisher's test was used, and for continuous variables, an independent t-test was used. Binary logistic regression was used to investigate the influencing factors. Only statistically significant factors from the univariable logistic regression model were analyzed further in the multivariable logistic regression model. SPSS 26.0 (IBM Corp., Armonk, NY, USA) for Windows was used for all statistical analysis. Statistical significance was defined as a p-value of less than 0.05.