Awareness, Barriers and Concerns of Adolescents Toward the COVID-19 Vaccine: A Cross-Sectional Study in Singapore

Background COVID-19 vaccination is a key public health measure to mitigate the crippling effects of the pandemic. COVID-19 vaccination began in adults and targeted adolescents at a later stage. However, medical decision-making on its uptake among the latter was unknown, which could be affected by their literacy and concerns about the vaccine. The study aimed to elucidate the awareness, concerns and barriers of adolescents toward the COVID-19 vaccine. Methods A cross-sectional online survey using a self-developed questionnaire was conducted between June to November 2021. The adolescent participants were students from institutes of post-secondary education who were recruited via convenience sampling. The data were collated from an officially approved electronic platform, audited and analyzed. Continuous and categorical variables were expressed as mean (standard deviation) and percentages, respectively. Results A total of 460 adolescents participated in the study (mean age: 16.99 ± 0.99; 73% female). Most of them (91.5%) were aware of the COVID-19 vaccines. The main barriers to vaccination were uncertainty about long-term health risks (38.6%) and vaccine efficacy (37.3%). Regarding the potential vaccine side effects, they were concerned about: anaphylactic shock (73.2%), low blood pressure (58.3%) and fast heartbeat (58.0%). Only 58% expressed willingness for repeated COVID-19 vaccination. Conclusion Despite high COVID-19 vaccine awareness, the adolescents were concerned about the potentially severe but rare side-effects. The study identified apprehension regarding vaccine efficacy and the potential long-term health impact as the main barriers to vaccination. Future studies should address these concerns to scale vaccination programs among adolescents.


INTRODUCTION
Since the outbreak of the COVID-19 pandemic and the emergence of various strains, vaccinations have emerged as a key solution to curb its spread. COVID-19 vaccinations have been proven to reduce both the incidence and severity of infections (1,2). The CDC published data that fully vaccinated individuals were 5 times less likely to become infected and more than 10 times less likely to require hospitalization or succumb to . Some of the barriers to vaccination include accessibility and vaccine hesitancy.
Vaccine hesitancy is defined as the delay in acceptance or vaccination refusal despite its availability (4). Rates of COVID-19 vaccine hesitancy of up to 35% and 58% have been reported in the US and China (5,6). Factors commonly associated with vaccine hesitancy include concerns over efficacy, adverse effects, safety and cost (7,8). It is crucial to elucidate the awareness, concerns and barriers to addressing vaccine hesitancy. Presently information is lacking on how the youth in Singapore perceive the COVID-19 vaccine.
Vaccinations were initially approved for individuals aged 18 years and above. On 10 th May 2021, the Pfizer R COVID-19 vaccination received Food and Drug Agency (FDA) approval for use in individuals aged 12 years and older (9). With individuals under 20 years of age constituting nearly 20% of Singapore's population, it is critical that those eligible are vaccinated promptly to scale up the herd immunity (10).
At the beginning of this study on 1 st June 2021, the vaccination rate among adults was 34% (11). In contrast, 2% of individuals between 12 and 19 years of age had completed the full regime due to phased-in vaccination for this age group. Almost all of these youths are students in schools, with those aged 16 years and older studying in institutes of higher learning such as junior colleges (or the equivalent of high schools), polytechnics and institutes of technical education. Cai et al. (12) found that 48.3% of polled Chinese adolescents were aware that COVID-19 vaccines could provide protection. Similar to adults, a study conducted among adolescents in Hong Kong reported concerns over vaccine safety (79%) and efficacy (52%) as barriers to COVID-19 vaccination (13). Information on the awareness, concerns and barriers preventing adolescents in Singapore from receiving the COVID-19 vaccine remains scarce despite its well-educated population.
Ruggeri et al. (14) reported that children and adolescents made different choices in medical decision-making. According to the authors, adolescents want to be responsible for their own medical decision, instead of their parents. They also highlighted the need to explore better approaches to involve adolescents in their medical decision-making process. The uptake of the COVID-19 vaccine requires medical decision-making but the process of reaching such a decision among older adolescents has yet to be determined. Understanding the perspectives of adolescents in this age group will allow public health policymakers to assess their eventual COVID-19 vaccine uptake.
Hence, this survey aimed to determine the willingness of older adolescents to take up the COVID-19 vaccine and to identify their concerns, awareness and barriers to the vaccine in Singapore.

Study Design
This cross-sectional study was implemented as a web-based questionnaire survey. The online survey eased the dissemination to the target participants without physical contact in a pandemic, which also allowed participants to complete the survey anonymously without any undue external pressures.

Population
This study was conducted among adolescents aged between 16 and 17 years of age to determine their concerns, awareness and deterring factors toward the COVID-19 vaccine. They were post-secondary students in junior colleges, polytechnics and Institutes of Technical Education (ITE). Junior colleges are the equivalent of high schools, whereas polytechnics provide more practice-based learning experiences culminating in a diploma. ITE provides technical and vocational education (15).

Questionnaire Design
The survey consisted of 6 domains: demographic, history of severe allergic reaction to vaccines or medications, knowledge and attitude on the vaccine, concerns about the vaccination, factors influencing their vaccine uptake and willingness to proceed with COVID-19 vaccinations. Participants filled in their gender, ethnicity, year of birth and sites of Institute of Higher Learning but no participant identifier was collected. The questionnaire allowed them to respond by selecting either binary (Yes/No) or multiple allowable options. The questionnaire underwent face validation by a group of polytechnic students in an unpublished study.

Awareness of the COVID-19 Vaccine
Awareness of common facts about the COVID-19 vaccine was assessed via questions regarding its efficacy, potential side-effects and cost.

Concerns About the COVID-19 Vaccine
Concerns about the COVID-19 vaccine side-effects were determined by asking participants about their concerns regarding specific side-effects. The side-effects ranged from common but mild symptoms such as tiredness to more severe side-effects such as anaphylactic shock.

Barriers to COVID-19 Vaccination
Barriers to COVID-19 vaccination were assessed via questions encompassing vaccine accessibility, vaccine administration and COVID-19 vaccine-specific factors including efficacy and potential long-term side-effects.

E-Survey Design and Subject Recruitment
The e-survey was conducted from 1 st June to 30 th November 2021. The study team formulated a preliminary set of survey questions using Google Forms. After the finalization of the survey questions on Google Forms, the final survey was then created using the form builder tool called "FormSG, " which is a national survey platform to create digital government forms developed by Singapore's GovTech's Data Science & Artificial

Statistical Analysis
Descriptive statistics were done to describe the sample and associations performed to consider relationships between gender and ethnicity with concerns and willingness to get COVID-19 booster jabs. Continuous and categorical variables were expressed as mean (standard deviation) and percentages, respectively.

Subject Demographics
The demographic characteristics are shown in    Barriers to COVID-19 Vaccination Figure 1 shows the deterring reasons to vaccination. Vaccine efficacy (37.4%) and risk to long-term health (38.7%) were the most common deterring reasons to vaccination. A small proportion of adolescents (9.3%) responded that they were not sure about the application procedures as a reason for not getting vaccinated.

DISCUSSION
The surveyed adolescents displayed high literacy of COVID-19 vaccines, such as vaccine efficacy, its side-effects (including non-interference with DNA), cost and implementation for local residents. In contrast, a 2020 survey by the Nanyang Technical University of Singapore showed one in four Singaporeans falsely believed that the COVID-19 vaccine alters DNA (16). Unfortunately, their awareness did not include other uncommon COVID-19 vaccine-related adverse effects. About 19% of respondents were aware of the potential for the vaccine to cause a fast heartbeat and anaphylactic shock. Unsurprisingly, the potential adverse effects with the least awareness were those that these adolescents were most concerned with, reflecting the need for further deliberations. While these concerns should be addressed, it is important to strike a good balance between ensuring that individuals obtain the necessary information to make an informed decision without inducing unnecessary fear that may adversely affect vaccination rates. Vaccine hesitancy was related to its perceived efficacy (37.4%) and effect on long-term health (38.7%). The vaccine has been proven to be efficacious with current available data not suggesting any known long-term detrimental effects to one's health (1). More adolescents were concerned about vaccine efficacy than the 24% reported by a US study conducted among college students (17). Interestingly, the concerns over vaccine efficacy are in contrast to the good awareness that many respondents had regarding the efficacy of vaccination. This reveals a gap between the knowledge and its application. These concerns need to be addressed and identifying the best avenue to do so is imperative.
Most adolescents reported obtaining information from family (80.0%) and mainstream media (78.2%). In contrast, around 25% reported obtaining information from teachers and school briefings. With adolescents spending extended periods of their day in school, the education professionals should not miss the opportunity to provide them with the requisite knowledge and opportunity to clarify any doubts regarding the COVID-19 vaccine.
The study revealed that only 58% of participants were willing to undergo repeated COVID-19 vaccinations to maintain their immunity. As of 10 th February 2022, 96% of adolescents aged 12 to 19 years of age received their primary doses of COVID-19 vaccines (11). The difference between the survey results and the actual vaccination rates could be explained by vaccine approval and government-led campaigns. On 10 th June 2021, the Pfizer R COVID-19 vaccine became the first vaccine approved for use in Singapore for individuals aged 12 to 17 years of age (18). This presented the only available vaccination option for youths in this age group. Should they be medically ineligible to receive the Pfize R vaccine, they would be eligible to receive the Sinovac R vaccine via the Pediatric Sinovac R after mRNA (SAM) public health program (19). Access to the Sinovac R vaccine is regulated because the Singapore Ministry of Health Expert Committee determined that it was lower in efficacy compared to the Pfizer R vaccine in addition to the lack of World Health Organization (WHO) approval for use in this population (19,20). Locally, the inability to opt for a non-mRNA vaccine option in this age group does not seem to have significantly affected the vaccine uptake rates. Apart from vaccine availability, government-led campaigns such as VacciNationSg were introduced in March 2021 to improve public awareness of the COVID-19 vaccination (21). Following the approval of the Pfizer R vaccine for use in those aged 12 to 17 years of age, specific material aimed at this demographic was disseminated via not only traditional but also digital platforms including TikTok, Twitter and Instagram. The impact of these measures may account for the vaccination rate being higher than the 57% reported by the United States in youths aged 12 to 17 years of age (22).
Following the positive uptake of primary COVID-19 vaccinations, booster vaccinations will be required as immunity wanes with time. National healthcare policies were introduced to foster positive uptake of the booster through the Booster Vaccination Program. The government announced on 21 st January 2022 that individuals aged 12 years and above would only be considered fully vaccinated once they receive the booster vaccination with effect from 14 th March 2022 (23). Once eligible, parents of individuals between 12 and 17 years of age received a text message to schedule their booster vaccination. Since November 2021, vaccine-differentiated Safe Management Measures (SMMs) aimed to reduce the risk to non-fully vaccinated individuals by restricting their access to high-risk settings. These measures include being unable to enter shopping  centers or dine-in restaurants (24). Individuals may be motivated to receive the booster dose to avoid inconveniencing their daily activities. These policies incentivize the public to comply with vaccination recommendations for the collective good of the populace.

Strengths and Limitations
The use of an electronic questionnaire survey is a strength of this study. An e-survey offers a cost-free and convenient recruitment method to reach out to adolescents, who are likely to be tech-savvy and comfortable with navigating the internet in a highly digitalized community like Singapore. Using a secured and officially approved digital platform that local residents are familiar with, enhances the confidence of the adolescents to participate in the survey.
Nonetheless, the data was collected via an e-survey, which could have resulted in more responses from motivated individuals who participated in the study. The sampling can be skewed as reflected by the higher proportion of female and Chinese ethnicity compared to the baseline demographics expected in this age group.

Future Work
The COVID-19 vaccination uptake thus far has been promising with 96% of youth between 12 and 19 years of age having completed the primary vaccination (11). With the next phase being booster vaccinations, armed with the information gathered in this survey, the VacciNationSG campaign can be further tailored to address some of the concerns and barriers to vaccination with the delivery of information utilizing platforms such as schools. Supplementary services such as hotlines and online portals can be further promoted to provide individuals with accurate information promptly.

CONCLUSION
The study identified concerns and barriers to vaccination with only slightly more than half of the participants being willing to undergo repeated vaccinations. Overall the local adolescents had high COVID-19 vaccine awareness with concerns over the potentially severe, albeit rarer, side-effects. Apprehension regarding vaccine efficacy and the potential long-term impact on health were the main barriers to vaccination and needs to be addressed promptly to facilitate possible repeat vaccination when robust evidence becomes available in the future.

DATA AVAILABILITY STATEMENT
The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.

ETHICS STATEMENT
The studies involving human participants were reviewed and approved by Institutional Review Board at Hwa Chong Institution. Written informed consent from the participants' legal guardian/next of kin was not required to participate in this study in accordance with the national legislation and the institutional requirements.