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Expert Review of Vaccines
ISSN: (Print) (Online) Journal homepage: https://www.tandfonline.com/loi/ierv20
Willingness to receive a booster dose of
inactivated coronavirus disease 2019 vaccine in
Taizhou, China
Tao-Hsin Tung, Xiao-Qing Lin, Yan Chen, Mei-Xian Zhang & Jian-Sheng Zhu
To cite this article: Tao-Hsin Tung, Xiao-Qing Lin, Yan Chen, Mei-Xian Zhang & Jian-Sheng Zhu
(2021): Willingness to receive a booster dose of inactivated coronavirus disease 2019 vaccine in
Taizhou, China, Expert Review of Vaccines, DOI: 10.1080/14760584.2022.2016401
To link to this article: https://doi.org/10.1080/14760584.2022.2016401
Published online: 22 Dec 2021.
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ORIGINAL RESEARCH
Willingness to receive a booster dose of inactivated coronavirus disease 2019
vaccine in Taizhou, China
Tao-Hsin Tung
a
, Xiao-Qing Lin
b
, Yan Chen
b
, Mei-Xian Zhang
a
and Jian-Sheng Zhu
b
a
Evidence-based Medicine Center, Taizhou Hospital of Zhejiang Province, Wenzhou Medical University, Linhai, Zhejiang, China;
b
Department of
Infectious Diseases, Taizhou Hospital of Zhejiang Province, Wenzhou Medical University, Linhai, Zhejiang, China
ABSTRACT
Purpose: This population-based study aimed to determine the willingness to receive a booster dose of
vaccine against coronavirus disease (COVID-19) in Taizhou, China.
Methods: An online questionnaire investigation addressing participants’ willingness to receive
a booster dose of the COVID-19 vaccine was organized in Taizhou, China. Of the 2318 interviewees
who received the invitation, 1576 finished a qualifying questionnaire, corresponding to a response rate
of 68.0%.
Results: The majority of respondents (n = 1435 [91.1%]) were willing to accept a booster vaccination
against COVID-19. History of allergic reaction to other vaccines (OR = 0.30), confidence in the safety of
the COVID-19 vaccines (OR = 3.20), confidence in the effectiveness of the COVID-19 vaccines against
SARS-CoV-2 (OR = 2.25) and its variants (useful versus [vs.] useless, OR = 2.33), and vaccine recipients
(OR = 3.09) remained significantly associated with willingness to accept a booster dose of COVID-19
vaccines.
Conclusion: A moderate proportion of the participants who responded were willing to receive
a booster dose of the COVID-19 vaccine. These results are valuable for starting health education and
interventions to accelerate vaccine uptake and improve public health outcomes during the COVID-19
pandemic in China.
ARTICLE HISTORY
Received 14 November 2021
Accepted 7 December 2021
KEYWORDS
COVID-19; willingness;
booster dose; China
1. Introduction
The coronavirus disease 2019 (COVID-19) pandemic has lasted
for nearly two years, and vaccines for severe acute respiratory
syndrome coronavirus 2 (SARS-CoV-2) have been available for
one year; nevertheless, the global pandemic continues [1]. The
outbreak occurred all over the world, and there have been
several resurgent outbreaks in China [2]. Recently, it has been
reported that some fully vaccinated individuals can still experi-
ence infection with SARS-CoV-2, or be hospitalized for or even
die of COVID-19 [3]. A breakthrough infection is defined as the
detection of SARS-CoV-2 RNA or antigen in a respiratory speci-
men collected from an individual ≥14 days after completion of
all recommended doses of licensed COVID-19 vaccine(s) [4].
This brings new challenges to regular prevention and control
of the epidemic situation. The COVID-19 pandemic remains
dangerous and, as such, needs to be taken seriously.
As of 30 November 2021, a total of 2.5 billion doses of two
inactivated vaccines (Sinopharm vaccine and Sinovac-
CoronaVac) have been administered in mainland China, and
more than 1.1 billion individuals received the full-schedule of
vaccination. These vaccines have been shown to be generally
safe and good immunogenicity profile as seen in phase 1, 2,
and 3 clinical trials [5–9]. A real-world evidence suggested that
the effectiveness against the Delta variant for two-dose vacci-
nation was 59.0% against overall COVID-19, with 70.2%
against moderate COVID-19, and 100% against severe
COVID-19 [10]. On the other hand, their findings suggested
the need to continuously enforce mass vaccination, including
booster vaccination, because of the occurrence of break-
through cases [11].
SARS-CoV-2 variants and declines in vaccine efficacy over
time are believed to be responsible for the resurgence of the
epidemic [12]. Vaccine-induced antibodies are the main barrier
against infection, and the antibody response to vaccination is
the most important biomarker of vaccine efficacy [13]. It is
known that the effect of inactivated vaccines is not as long as
a live vaccine that continuously stimulates the immune system
[14]. Previous studies have shown that vaccine-induced neu-
tralizing antibody titers decrease over time, and the lower the
neutralizing antibody titers, the higher the risk for infection(s)
[15]. A retrospective study of health-care personnel who
received two doses of the COVID-19 vaccine indicated that
the antibody levels detected 60 days after vaccination were
lower than those detected within 60 days after receiving
CoronaVac [16]. The immune system requires time to prepare,
with the first step sensitization; the second and third are to
activate a large number of memory cells. The abundance and
maturity of antibody induced by the third dose were signifi-
CONTACT Jian-Sheng Zhu zhujs@enzemed.com; Mei-Xian Zhang meixian0116@163.com Department of Infectious Diseases, Taizhou Hospital of
Zhejiang Province, Wenzhou Medical University, 150 Ximen Street, Linhai 317000, Zhejiang Province, China
EXPERT REVIEW OF VACCINES
https://doi.org/10.1080/14760584.2022.2016401
© 2021 Informa UK Limited, trading as Taylor & Francis Group
cantly higher than those induced by the second dose.
Therefore, timely vaccination with a third booster shot to
increase further neutralizing antibody titers in the body can
complement and enhance the declining protective efficacy of
the vaccine, as well as dealing with the delta variant and and
deal with the delta variant the ‘X’ variant, which may appear at
any time. Vaccine hesitancy is an essential factor hindering
widespread vaccination strategies. Prompted by the small
number of studies investigating the willingness to receive
booster shots, this study aimed to understand the public’s
willingness to receive booster shots against COVID-19. The
findings could be used to inform measures aimed at promot-
ing booster shots among the general population as soon as
possible, which in turn may better control the spread of
disease.
2. Methods
2.1. Study design and data collection
An anonymous, cross-sectional, population-based online sur-
vey was administered using the WeChat-Inc Wen-Juan-Xing
platform, which is the largest online survey platform in
China. The target population was self-identifying parents
who had a child <18 years of age. A convenient sample in
Taizhou, China, was selected to receive an invitation for the
survey via WeChat. The interviewees completely volunteered
to answer the self-administered questionnaire by scanning the
quick response (i.e. ‘QR’) code on their mobile smartphones
from August 5 to 11, 2021. The inclusion criteria for this study
were all parents who received the invitation letter and volun-
teered to complete the questionnaire. The unqualified ques-
tionnaires that contained unreasonable information or were
answered too quickly were excluded. Finally, 1576 intervie-
wees with valid data were included in this study, correspond-
ing to a response rate of 68.0% (1576/2318). The present study
was exempted from requirements for written informed con-
sent and was approved by the Ethics Committee of Taizhou
Hospital of Zhejiang Province (Approval number: K20210705)
in China. All the procedures were performed in accordance
with the guidelines of the authors’ institutional ethics commit-
tee and adhered to the tenets of the Declaration of Helsinki.
2.2. Structured questionnaires and measurement
An online self-administered questionnaire consisting of several
parts was constructed. The introduction of the questionnaire
described the background and purpose of the survey and
stated that the questionnaire will be answered anonymously
and voluntarily following informed consent. Basic demo-
graphic information included age, sex, residence, education
level, and occupation. Personal background information con-
sisted of underlying diseases and a history of allergic reaction
to vaccines. Risk perception of COVID-19 was measured using
the question: ‘How much do you think you are at risk of being
infected with SARS-CoV-2?’ Five response options were
offered: very high, high, moderate, and low or very low. The
first two options were merged into high, and the last two were
merged into low in the final analysis.
The major topics of the questionnaire included knowledge,
attitude, practice, and willingness to receive COVID-19 vac-
cines. Overall knowledge about the COVID-19 vaccine was
measured using the following question: ‘How much do you
know about the COVID-19 vaccines?’ Five response options
were offered: very well, well, relatively moderate, unknown,
and not at all. Confidence in the safety of COVID-19 vaccines
was assessed on a 5-point Likert scale, as follows: very safe,
safe, moderate, unsafe, or very unsafe. Confidence in the
effectiveness of the vaccines on preventing COVID-19 was
rated on a 4-point Likert scale, as follows: great, relatively
great, moderate, or little. The interviewees were asked, ‘Do
you think the vaccine was effective against SARS-CoV-2 var-
iants?’ The response options were useful, possibly useful, not
sure, possibly useless, and useless. For simplification, the
responses to knowledge, safety, and preventive effect of the
COVID-19 vaccine, as well as effectiveness against SA,RS-CoV-2
variants were recoded during the final analysis, with the first
two options recoded as high (useful), and the others recoded
as low (useless). In addition, interviewees’ willingness to
receive a booster vaccination was measured using the ques-
tion, ‘Would you like to accept the booster dose of the COVID-
19 vaccine to enhance its protective effect?’ The response
options were strongly willing, willing, unwilling, or strongly
unwilling. The first two options were merged into willing and
the others were merged into unwilling during the final
analysis.
2.3. Statistical analysis
We performed a logical check of the data, excluding those
who were under the age of 18 or over the age of 70, excluding
those who answered within 120 seconds. Categorical variables
regarding basic characteristics are expressed as count and
percentage; the chi-squared test was used to initially assess
differences in demographic and personal background vari-
ables between participants with and without willingness to
receive vaccination with a booster dose. A binary logistic
regression model was used to identify factors influencing the
willingness to receive a vaccine booster dose, and the odds
ratio (OR) and corresponding 95% confidence interval (CI)
were calculated. All data were analyzed using SPSS version
22.0 (IBM Corporation, Armonk, NY, USA). Differences with
P < 0.05 were considered to be statistically significant.
3. Results
In the present study, 1576 questionnaires underwent data
analysis. The mean (± SD) age was 40.4 ± 5.6 years, and 77%
of them were female. Most respondents (n = 1515 [96.1%])
had been vaccinated against COVID-19. The characteristics
and willingness for booster vaccination acceptance against
COVID-19 in vaccinated and unvaccinated participants are
summarized in Table 1. There were no differences in sex,
age, residence, or educational level between those who were
willing and unwilling to receive a vaccine booster (P > 0.05). As
shown in Figure 1, the majority of respondents (n = 1435
[91.1%]) were willing to accept booster vaccination against
COVID-19, with 1142 (72.5%) willingness and 293 (18.6%)
2T-H. TUNG ET AL.
Table 1. Respondents’ characteristics and booster vaccination acceptance against COVID-19 (n = 1576).
Independent Variables
Total Sample,
N (%)
Booster COVID-19 vaccination
acceptance
Vaccinated
subsample, N (%)
Booster COVID-19 vaccination
acceptance
Unvaccinated
subsample, N (%)
Booster COVID-19 vaccination
acceptance
Unwilling to
accept,
Willing to
accept,
P
Unwilling to
accept,
Willing to
accept,
P
Unwilling to
accept,
Willing to
accept,
Pn (%) n (%) n (%) n (%) n (%) n (%)
Total 1576 (100) 141 (8.9) 1435 (91.1) 1515 (100) 124 (8.2) 1391 (91.8) 61 (100) 17 (27.9) 44 (72.1)
Age 0.052 0.097 0.178
≥40 years 827 (52.5) 85 (10.3) 742 (89.7) 796 (52.5) 74 (9.3) 722 (90.7) 31 (50.8) 11 (35.5) 20 (64.5)
<40 years 749 (47.5) 56 (7.5) 693 (92.5) 719 (47.5) 50 (7.0) 669 (93.0) 30 (49.2) 6 (20.0) 24 (80.0)
Sex 0.115 0.242 0.121
Male 363 (23.0) 40 (11.0) 323 (89.0) 351 (23.2) 34 (9.7) 317 (90.3) 12 (19.7) 6 (50.0) 6 (50.0)
Female 1213 (77.0) 101 (8.3) 1112 (91.7) 1164 (76.8) 90 (7.7) 1074 (92.3) 49 (80.3) 11 (22.4) 38 (77.6)
Residence 0.610 0.353 0.544
Rural/town 364 (23.1) 35 (9.6) 329 (90.4) 352 (23.2) 33 (9.4) 319 (90.6) 12 (19.7) 2 (16.7) 10 (83.3)
Urban 1212 (76.9) 106 (8.7) 1106 (91.3) 1163 (76.8) 91 (7.8) 1072 (92.2) 49 (80.3) 15 (30.6) 34 (69.4)
Education level 0.179 0.256 0.273
Senior Secondary
and below
778 (49.4) 62 (8.0) 716 (92.0) 746 (49.2) 55 (7.4) 691 (92.6) 32 (52.5) 7 (21.9) 25 (78.1)
University and above 798 (50.6) 79 (9.9) 719 (90.1) 769 (50.8) 69 (9.0) 700 (91.0) 29 (47.5) 10 (34.5) 19 (65.5)
Suffering from chronic diseases 0.006 0.178 0.095
Yes 163 (10.3) 24 (14.7) 139 (85.3) 144 (9.5) 16 (11.1) 128 (88.9) 19 (31.1) 8 (42.1) 11 (57.9)
No 1413 (89.7) 117 (8.3) 1296 (91.7) 1371 (90.5) 108 (7.9) 1263 (92.1) 42 (68.9) 9 (21.4) 33 (78.6)
History of allergic reaction to other vaccines <0.001 <0.001 0.144
Yes 135 (8.6) 34 (25.2) 101 (74.8) 124 (8.2) 29 (23.4) 95 (76.6) 11 (18.0) 5 (45.5) 6 (54.5)
No 1441 (91.4) 107 (7.4) 1334 (92.6) 1391 (91.8) 95 (6.8) 1296 (93.2) 50 (82.0) 12 (24.0) 38 (76.0)
Risk perception of COVID-19 0.793 0.519 1.000
High 281 (17.8) 24 (8.5) 257 (91.5) 264 (17.4) 19 (7.2) 245 (92.8) 17 (27.9) 5 (29.4) 12 (70.6)
Low 1295 (82.2) 117 (9.0) 1178 (91.0) 1251 (82.6) 105 (8.4) 1146 (91.6) 44 (72.1) 12 (27.3) 32 (72.7)
Have you been following the news of the COVID-19 vaccines? 0.057 0.018 0.927
Yes 1469 (93.2) 126 (8.6) 1343 (91.4) 1410 (93.1) 109 (7.7) 1301 (92.3) 59 (96.7) 17 (28.8) 42 (71.2)
No 107 (6.8) 15 (14.0) 92 (86.0) 105 (6.9) 15 (14.3) 90 (85.7) 2 (3.3) 0 2 (100.0)
Knowledge on the COVID-19 vaccines <0.001 <0.001 0.197
High 1073 (68.1) 76 (7.1) 997 (92.9) 1033 (68.2) 67 (6.5) 966 (93.5) 40 (65.6) 9 (22.5) 31 (77.5)
Low 503 (31.9) 65 (12.9) 438 (87.1) 482 (41.8) 57 (11.8 425 (88.2) 21 (34.4) 8 (38.1) 13 (61.9)
Confidence in safety of the COVID-19 vaccines <0.001 <0.001 <0.001
High 1222 (77.5) 55 (4.5) 1167 (95.5) 1186 (78.3) 53 (4.5) 1133 (95.5) 36 (59.0) 2 (5.6) 34 (94.4)
Low 354 (22.5) 86 (24.3) 268 (75.7) 329 (21.7) 71 (21.6) 258 (78.4) 25 (41.0) 15 (60.0) 10 (40.0)
Confidence in effectiveness of the COVID-19 vaccines <0.001 <0.001 <0.001
High 1191 (75.6) 57 (4.8) 1134 (95.2) 1154 (76.2) 54 (4.7) 1100 (95.3) 37 (60.7) 3 (8.1) 34 (91.9)
Low 385 (24.4) 84 (21.8) 301 (78.2) 361 (23.8) 70 (19.4) 291 (80.6) 24 (39.3) 14 (58.3) 10 (41.7)
Do you think the vaccine is effective against SARS-CoV-2 variants? <0.001 <0.001 <0.001
Useful 1275 (80.9) 74 (5.8) 1201 (94.2) 1229 (81.1) 67 (5.5) 1162 (94.5) 46 (75.4) 7 (15.2) 39 (84.8)
Useless 301 (19.1) 67 (22.3) 234 (77.7) 286 (18.9) 57 (19.9) 229 (80.1) 15 (24.6) 10 (66.7) 5 (33.3)
EXPERT REVIEW OF VACCINES 3
had strong willingness to receive a vaccine booster shot, while
141 (8.9%) reported that they were unwilling or strongly
unwilling to accept the booster vaccination. The willingness
to receive a booster shot in the vaccinated participants was
similar to the total sample (91.8% vs. 91.1%). Interestingly,
72% of unvaccinated participants reported a willingness to
receive booster shots, although it was significantly lower
than among those who had been vaccinated (72.1% vs.
91.8%, P < 0.001).
Results from univariate analysis (Table 1) revealed that the
willingness to accept booster vaccination against COVID-19
was significantly lower among respondents with chronic dis-
eases, such as hypertension, diabetes, chronic liver disease,
and kidney disease, those with a positive history of allergic
reactions to other vaccines, those knowing less about the
COVID-19 vaccine, those with low confidence in the safety of
the COVID-19 vaccines, those who believe that the COVID-19
vaccines have no effect on preventing infection with SARS-
CoV-2 and its variants, and those who had not been vacci-
nated compared with their counterparts (all P < 0.05). In both
vaccinated and unvaccinated participants, the willingness to
receive booster vaccination differed due to their confidence in
the safety and effectiveness of the vaccine and in its
prevention against the SARS Cov-2 virus variant. Besides, the
willingness of the vaccinated population was also related to
history of allergic reactions to other vaccines, interest in vac-
cine information, and knowledge of the COVID-19 vaccines.
We further calculated the magnitude of association
between these factors and willingness to accept booster vac-
cination in binary logistic regression models. As shown in
Table 2, history of allergic reaction to other vaccines (OR
0.30 [95% CI 0.18–0.49]), confidence in the safety of the
COVID-19 vaccines (OR 3.20 [95% CI 2.07–4.97]), confidence
in the effectiveness of the COVID-19 vaccines against SARS-
CoV-2 (OR 2.25 [95% CI 1.44–3.53]) and its variants (useful vs.
useless, OR 2.33 [95% CI 1.54–3.55]), and vaccine recipients
(OR 3.09 [95% CI 1.53–6.23]) were significantly associated with
willingness to receive the booster dose of the COVID-19 vac-
cines, while chronic disease history (OR 0.90 [95% CI 0.51–
1.59]) and knowledge about the COVID-19 vaccine (OR 0.93
[95% CI 0.62–1.40]) were no longer statistically significant after
adjustment for age and sex. After stratified by vaccination
status, the related factors of booster vaccination intention in
the vaccinated subsample were consistent with the whole
sample. However, the willingness of unvaccinated subsample
to receive the booster vaccination was only significantly asso-
ciated with their confidence in the prevention against the
SARS Cov-2 virus variants (OR 7.49 [95% CI 1.25–45.07]).
4. Discussion
Faced with the attenuating immune response to the
COVID-19 vaccine, several clinical studies have been per-
formed to investigate the immunogenicity, safety, and effi-
cacy of the COVID-19 vaccine booster dose [17]. The data
provided strong scientific evidence that the booster dose
of COVID-19 vaccine could increase the titer of neutralizing
antibody and the scope of protection [18,19]. Although
studies have found that the neutralizing antibody titers
increase differently with different vaccine technology
routes, it could not be denied that the COVID-19 vaccine
Figure 1. Willingness to accept the booster dose of COVID-19 vaccine in
vaccinated and unvaccinated participants.
Table 2. Multiple logistic regression of factors associated with willingness to accept booster dose of COVID-19 vaccines that all univariate significant factors were
included among the study samples (n = 1576).
Independent Variables
All (n = 1576) Vaccinated (n = 1515) Unvaccinated (n = 61)
P OR (95%CI)P OR (95%CI)P OR (95%CI)
Suffering from chronic diseases (yes vs. no) 0.718 0.90 (0.51–1.59) – – – –
History of allergic reaction to other vaccines (yes vs. no) <0.001 0.30 (0.18–0.49) <0.001 0.28 (0.17–
0.46)
–
Following the news of the COVID-19 vaccines (yes vs. no) – – 0.792 1.09 (0.57–
2.10)
– –
Knowledge on the COVID-19 vaccine (high vs. low) 0.727 0.93 (0.62–1.40) 0.829 0.95 (0.62–
1.46)
– –
Confidence in the safety of the COVID-19 vaccines (high vs. low) <0.001 3.20 (2.07–4.97) <0.001 2.97 (1.88–
4.68)
0.054 7.23 (0.97–54.00)
Confidence in the effectiveness of the COVID-19 vaccines (high vs. low) <0.001 2.25 (1.44–3.53) <0.001 2.19 (1.37–
3.49)
0.144 4.63 (0.59–36.10)
Do you think the vaccine is effective against SARS-CoV-2 variants? (useful vs.
useless)
<0.001 2.33 (1.54–3.55) <0.001 2.19 (1.41–
3.42)
0.028 7.49 (1.25–45.07)
Have you been vaccinated against COVID-19? (yes vs. no) 0.002 3.09 (1.53–6.23) – – – –
Adjusted for sex and age.
4T-H. TUNG ET AL.
booster dose can again stimulate the body’s immune
response, enhancing the protective effect of vaccine
against various SARS-CoV-2 variants such as the Delta var-
iant. Results of the present study indicated that a high
proportion (91.1%) of participants would receive
a booster dose of COVID-19 vaccine, which was consistent
with the acceptance rate of primary vaccination reported
in previous studies in China (91.3%) [20]. Effectiveness and
safety of the COVID-19 vaccines are both significant factors
related to booster dose. Academic studies have revealed
satisfactory protection of the two-dose regimens of vac-
cines against COVID-19 in individuals <16 years of age.
Safety over a median of 2 months was similar to that of
other viral vaccines [7,21,22]. This concern should be
further incorporated into vaccine communication cam-
paigns and interventions for booster doses, both to
improve vaccine uptake intent and potentially increase
willingness to receive booster doses of COVID-19 vaccine.
By fitting the data into a logistic regression model, the OR
for the vaccine’s effectiveness against SARS-CoV-2 variants was
estimated to be 2.33 (95% CI 1.54–3.55) in the useful group
compared with the useless group. This finding not only sug-
gests that positive attitudes may influence the willingness to
receive a booster dose but also implies that clinicians should
plan and administer a booster dose after two doses of
CoronaVac are appropriate for individuals in risk groups with
confidence improvement. Doing so will establish and preserve
the continuity of the herd immunity [19].
It is not surprising that both high knowledge about the
COVID-19 vaccine and vaccination against COVID-19
related to the willingness to receive a booster dose of
COVID-19 vaccine. From a preventive medicine perspective,
vaccination remains an effective means of strengthening
the management and control of infectious diseases.
Following the World Health Organization (WHO) report of
the Delta variant, several confirmed cases of the Delta
variant infection were identified in Nanjing, China, on
20 July 2021. The outbreak then spread rapidly through
several provinces. During the study period, the epidemic
was well controlled in Nanjing, and the daily increase of
newly diagnosed cases all over the country reached a peak,
while the daily growth of vaccination began to decline
after peaking on 3 August 2021. In the face of the global
COVID-19 resurgence, many countries have introduced
a booster vaccination in high-risk populations. China’s
Joint State Council on COVID-19 prevention and control
mechanism issued a strategy for booster vaccination
against COVID-19 for key populations. It is not known
whether the booster strategy will also be applied to the
general population, which depends on the need for pre-
vention and control of the epidemic, as well as relevant
research data.
There were several limitations of methodological con-
sideration in this study. First, because Taizhou is only
a relatively small area of China, the results may not be
representative of the entire country; in other words, the
findings may have limited generalizability. Second, a social
desirability bias may have been introduced because sub-
jects tend to respond to beneficial options. Third, the
study sample was selected on a voluntary basis. Potential
subjects who completed the questionnaire would poten-
tially introduce selection bias. Moreover, the ‘Hawthorne
effect’ is inevitable because the participants were indivi-
duals who made a conscious decision. Voluntary bias could
be viewed as a fact that a particular sample could contain
only participants who are actually willing to participate in
the study and find the topic particularly interesting are
more likely to volunteer, similar to those who are expected
to be evaluated at a positive level [23]. Fourth, because
three-generation families are common in China, parents
are often the main decision-makers in the family and
have a strong influence on whether family members,
including their children, the elderly and themselves,
receive the vaccine. At present, children aged 3 years and
above are being vaccinated for the first time, and adults
including the elderly are being receive booster vaccination,
so it is particularly important to investigate the willingness
of parents with children. Although the study samples for
interviewees with less than 18 years old children are rela-
tively young and less representative of the general popula-
tion, the acceptance rate of primary doses of COVID-19
vaccine was close to previous study in China [20]. Fifth,
we did not investigate the reasons for willingness and
unwillingness, which is important to increase the practical
significance of this study. Finally, during the period of the
questionnaire survey, the COVID-19 outbreak in Taizhou
was well controlled, although the epidemic was across
the country. Our estimates were explored at only one
time point and, by clear assessment, could not be applied
to consider long-term effects. Moreover, the impact of the
rush of the outbreak on intentions for vaccination was not
determined. Further epidemiological and longitudinal
investigations are essential not only to extrapolate the
findings to other regions of China but also to better under-
stand the causal relationship between factors and willing-
ness to increase acceptance of booster doses of COVID-19
vaccines.
In conclusion, results of this study indicated that a high
proportion of subjects reported a willingness to receive
a booster dose of COVID-19 vaccine. The findings imply
the importance of detailed assessment and more health
education planning that increase confidence in the safety
and effectiveness of vaccines in China. Comprehensive pub-
lic policy plans are needed for a booster dose of COVID-19
vaccines to reduce the risk of repeated widespread
outbreaks.
Acknowledgments
We would like to thank the participants for their cooperation and support.
Author contributions
J.S. Zhu and T.H. Tung conceived the study. M.X. Zhang, J.S. Zhu and T.H. Tung
designed the questionnaire. J.S. Zhu collected the data. M.X. Zhang was
responsible for the coding of the analyses. T.H. Tung and M.X. Zhang analyzed
EXPERT REVIEW OF VACCINES 5
and interpreted the data, and wrote the first draft of the paper. X.Q. Lin and
Y. Chen searched, sorted and interpreted the relevant literature. All authors
edited and approved the final manuscript.
Ethics approval and consent to participate
This study was exempted from informed consent and approved by the
Ethics Committee of Taizhou Hospital of Zhejiang Province (Approval
number: K20210705) in China.
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 received an honorarium for their
review work. Peer reviewers on this manuscript have no other relevant
financial or other relationships to disclose.
ORCID
Tao-Hsin Tung http://orcid.org/0000-0003-2097-8375
Xiao-Qing Lin http://orcid.org/0000-0003-4986-2835
Yan Chen http://orcid.org/0000-0002-4975-989X
Mei-Xian Zhang http://orcid.org/0000-0002-6538-7037
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6T-H. TUNG ET AL.
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EXPERT REVIEW OF VACCINES 7
