OBJECTIVE: Vaccine hesitancy has been a public health issue for some time now, but gained more attention during COVID-19 pandemic. This systematic review aimed to estimate the prevalence of COVID-19 vaccination hesitancy and identify factors affecting it among adolescents. MATERIALS AND METHODS: The preferred reporting items for systematic review and meta-analysis protocols (PRISMA-P 2020) was used. A search was performed in PubMed/ MEDLINE, EMBASE, Google Scholar, Herdin, and Cochrane databases on September 2023 using the key words: (COVID-19 OR SARS-COV OR corona virus) AND (Vaccination OR immunization) AND (adolescence OR teenagers OR youth) AND (hesitancy OR acceptance). Observational studies which determined the prevalence or risk factors for COVID-19 vaccine hesitancy among adolescents aged 10-19 years old were included. RESULTS: There were 5 good quality cross-sectional studies included. The prevalence of adolescents who did not want to be vaccinated ranged between 8.4% and 61.0%; while the prevalence of being unsure if they want to be vaccinated was between 31.6% and 88.0%. Factors associated with vaccine hesitancy included being economically disadvantaged, not having influenza vaccination, worrying about its effectiveness and safety, and low perceived necessity. CONCLUSION There is good quality evidence that COVID-19 vaccine hesitancy exists among adolescents. It is recommended that health workers should conduct information and education campaigns to iterate the effectiveness, safety, and misconceptions about of COVID-19 vaccination. Vaccination programs should also reach out to economically disadvantaged adolescents, and tapping parents and social media may be an effective strategy to improve vaccination acceptance among adolescents.
COVID-19 ; SARS-COV ; Severe acute respiratory syndrome-related coronavirus ; Vaccination ; Immunization ; Adolescent ; Adolescence ; Teenagers ; Youth

Persistent infection of high-risk human papillomavirus (HPV) is the leading cause of cervical cancer. In order to achieve the goal of cervical cancer elimination, the World Health Organization (WHO) proposed the "90-70-90" goal, one of which is "90% of girls fully vaccinated with HPV vaccine by age 15 years". Based on the epidemiological characteristics of HPV infection and the characteristics of HPV vaccine, it is important to give priority to female adolescents to be vaccinated with HPV vaccine. CAV Affiliated Association for Standardized Management and Practice of Immunization Program organized an expert group to develop an expert consensus on the immunization strategy and practice of human papillomavirus vaccine for female adolescents in the Yangtze River Delta region. This consensus introduces HPV infection and related disease burden, safety, efficacy and effectiveness of HPV vaccination for female adolescents, factors affecting the health benefits of HPV vaccination for female adolescents, current HPV vaccination strategies for female adolescents, the expert advice, common problems and precautions in the Yangtze River Delta region. This consensus is developed to guide HPV vaccination for female adolescents in the Yangtze River Delta region and provide reference for other regions.
Female ; Adolescent ; Humans ; Papillomavirus Vaccines ; Papillomavirus Infections/prevention & control* ; Human Papillomavirus Viruses ; Uterine Cervical Neoplasms/prevention & control* ; Consensus ; Vaccination ; Immunization Programs

BACKGROUND: Data on the immunogenicity and safety of heterologous immunization schedules are inconsistent. This study aimed to evaluate the immunogenicity and safety of homologous and heterologous immunization schedules. METHODS: Multiple databases with relevant studies were searched with an end date of October 31, 2021, and a website including a series of Coronavirus disease 2019 studies was examined for studies before March 31, 2022. Randomized controlled trials (RCTs) that compared different heterologous and homologous regimens among adults that reported immunogenicity and safety outcomes were reviewed. Primary outcomes included neutralizing antibodies against the original strain and serious adverse events (SAEs). A network meta-analysis (NMA) was conducted using a random-effects model. RESULTS: In all, 11 RCTs were included in the systematic review, and nine were ultimately included in the NMA. Among participants who received two doses of CoronaVac, another dose of mRNA or a non-replicating viral vector vaccine resulted in a significantly higher level of neutralizing antibody than a third CoronaVac 600 sino unit (SU); a dose of BNT162b2 induced the highest geometric mean ratio (GMR) of 15.24, 95% confidence interval [CI]: 9.53-24.39. Following one dose of BNT162b2 vaccination, a dose of mRNA-1273 generated a significantly higher level of neutralizing antibody than BNT162b2 alone (GMR = 1.32; 95% CI: 1.06-1.64), NVX-CoV2373 (GMR = 1.60; 95% CI: 1.16-2.21), or ChAdOx1 (GMR = 1.80; 95% CI: 1.25-2.59). Following one dose of ChAdOx1, a dose of mRNA-1273 was also more effective for improving antibody levels than ChAdOx1 (GMR = 11.09; 95% CI: 8.36-14.71) or NVX-CoV2373 (GMR = 2.87; 95% CI: 1.08-3.91). No significant difference in the risk for SAEs was found in any comparisons. CONCLUSIONS: Relative to vaccination with two doses of CoronaVac, a dose of BNT162b2 as a booster substantially enhances immunogenicity reactions and has a relatively acceptable risk for SAEs relative to other vaccines. For primary vaccination, schedules including mRNA vaccines induce a greater immune response. However, the comparatively higher risk for local and systemic adverse events introduced by mRNA vaccines should be noted. REGISTRATION PROSPERO; https://www.crd.york.ac.uk/PROSPERO/ ; No. CRD42021278149.
Adult ; Humans ; BNT162 Vaccine ; 2019-nCoV Vaccine mRNA-1273 ; Network Meta-Analysis ; Immunization Schedule ; COVID-19/prevention & control* ; COVID-19 Vaccines/adverse effects* ; Viral Vaccines ; mRNA Vaccines ; Antibodies, Neutralizing ; Antibodies, Viral

In order to increase the ability of oil-emulsion adjuvant to stimulate cellular immunity, chitosan hydrochloride with positive charge was selected to stabilize oil-in-water emulsion (CHE). In this paper, model antigen ovalbumin was selected to prepare vaccines with emulsion adjuvant, commercial adjuvant or no adjuvant. The emulsion was characterized by measuring the particle size, electric potential and antigen adsorption rate. BALB/c mice were immunized by intramuscular injection. Serum antibody levels, the numbers of IL-4-secreting cells in splenocytes, cytotoxic T lymphocyte (CTL) response, and the expression of central memory T cells were measured to evaluate the immunostimulatory effect. The results showed that chitosan hydrochloride can effectively stabilize the emulsion. The emulsion size is about 600 nm, and the antigen adsorption rate is more than 90%. After immunization, CHE could increase serum antibodies levels and increase IL-4 secretion. Expression of CTL surface activation molecules was also increased to stimulate CTL response further and to increase the CD44⁺CD62L⁺ in T cells proportion. CHE as adjuvant can stimulate humoral and cellular immunity more efficiently, and is expected to extend the duration of protection.
Animals ; Mice ; Chitosan ; Interleukin-4 ; Emulsions ; Immunization ; Adjuvants, Immunologic/pharmacology* ; Antigens ; Mice, Inbred BALB C

This study systematically retrieved information on the payment policy of vaccination fees for pneumococcal vaccines, human papillomavirus vaccines, haemophilus influenzae type b vaccines and rotavirus vaccines using a Python-based crawler. The proportion of the population covered by policies among the total applicable population was estimated based on the medical insurance coverage ratio and population data in 2020. This study showed that the payment policies included two categories, government-funded free vaccination policies and medical insurance payment policies. Among the four non-national immunization program vaccines, the free vaccination policies only involved pneumococcal vaccines and human papillomavirus vaccines. Among them, the 13-valent pneumococcal conjugate vaccine, the 23-valent pneumococcal polysaccharide vaccine, and the human papillomavirus vaccine were provided free of charge in 1, 10 and 15 provinces, respectively. For these policies, the corresponding covered population and the proportion among the total applicable population were children aged 6 months to 2 years old (2.5%), older people (1.2% to 21.5%) and middle school girls (1.1% to 12.2%). Medical insurance payment policies were implemented in 14 provinces, and nearly covered the four types of vaccines in the policy implementation areas, with the proportion of the covered population about 10.9% to 41.5% among the total applicable population.
Child ; Female ; Humans ; Infant ; Aged ; Pneumococcal Vaccines ; Vaccination ; Policy ; Immunization Programs ; Papillomavirus Vaccines ; China ; Vaccines, Conjugate

Objective: To systematically collect and evaluate the health economics research of Human papilloma virus(HPV) vaccination population expansion to men, and to provide evidence for optimizing HPV vaccine immunization strategies. Methods: Health economics research studies on male HPV vaccination published in databases including PubMed, Web of Science, CNKI, and Wanfang Database from January 2010 to September 2022 were collected according to the systematic evaluation research design. The quality of the studies was assessed using the health economics evaluation reporting standards (2022 edition) (CHEERS 2022), with full score of 28. The results of the studies were reviewed and analyzed systematically. Results: A total of 21 studies complies with the criteria were included, all of which was foreign research. The average CHEERS score of the literatures was 25.71 points, range from 23 to 28 points. 85.71% (12/14) studies of the gender-neutral population showed that including male in HPV vaccination were more consistent with the cost effectiveness than female vaccination alone under certain conditions (target at adolescents of 10 to 15 years old or adults under 26 years old). 80.00% (4/5) of the studies target at ordinary men only were proved that male vaccination with HPV vaccine was in line with the cost-effectiveness. 2 studies targeting men who have sex with men (MSM) were both concluded that it met the cost-effectiveness. In addition, the results of 2 gender-neutral population studies and 1 study on men alone showed that extending HPV vaccination to men did not conform to cost effectiveness. The main reasons for the non-cost-effectiveness included the high price of vaccines and the age of vaccination. Conclusion: The quality of the health economics evaluation studies on expanding HPV vaccination to the male population is high. Vaccination targeting adolescents and young men as well as special groups (such as MSM) are likely to be cost-effective, and vaccinations for other groups are still need further evaluated. It is recommended that relevant research should be conducted to provide evidence for expanding the scope of HPV vaccination to men in China.
Adult ; Adolescent ; Humans ; Male ; Female ; Child ; Human Papillomavirus Viruses ; Homosexuality, Male ; Papillomavirus Infections/prevention & control* ; Sexual and Gender Minorities ; Cost-Benefit Analysis ; Vaccination ; Immunization ; Papillomavirus Vaccines

The scientific setting and standardized management of adult vaccination clinics will improve the accessibility of vaccination services, thereby increasing the vaccination rate. Currently, some provinces and cities in China have been exploring the construction of adult vaccination systems for many years, effectively improving the level of vaccination services, and forming some useful experiences and models. However, the construction of China's adult vaccination system is not yet perfect, and the service mode needs to be optimized. In the future, we should continue to improve the guarantee measures for adult vaccination, scientifically lay out the network, optimize the service mode, and improve the overall quality of immunization services over the life course.
Adult ; Humans ; Life Change Events ; Immunization ; Vaccination ; China ; Cities

Bridging study in vaccine clinical trials means a series of small-scale additional tests on the basis that the original safety and effectiveness of a vaccine have been confirmed in clinical trials, to prove that the characteristics of safety, immunogenicity and effectiveness of a vaccine are similar or consistent after component, population and immunization procedure change to other types which can extrapolate data from existing clinical trials. Compared with traditional vaccine clinical trials, bridging trials can promote the approval of vaccines to the market, accelerate the expansion of vaccine application, and promote the use of vaccines across regions and populations. In recent years, the application of bridge study design in vaccine clinical research has become more and more common. In order to better guide and promote the application of bridging trial design in the field of vaccine clinical research, we reviewed the design characteristics and application examples of bridging study design in vaccine clinical trials, and systematically elaborated the design ideas, key points and statistical evaluation methods of bridging study.
Humans ; Research Design ; Biomedical Research ; Immunization ; Vaccines/therapeutic use*

INTRODUCTION: Cervical cancer has a high disease burden in Singapore, and it is strongly associated with human papillomavirus (HPV) infections. Despite constant efforts to encourage vaccination, local HPV vaccine uptake remains low. Universal mass vaccination is a proven cost-effective method to reduce the cervical cancer disease burden. This paper reviews the newly implemented school-based HPV vaccination programme in Singapore and the factors that led to its success. METHODS: Fully subsidised HPV vaccinations were offered to all Secondary 1 female students on an opt-in basis, starting as a rollout dose in 2019. One-time catchup vaccination was also offered to female students in Secondary 2-5. Eligible recipients were identified using enrolment data provided by Ministry of Education schools. A total of 19,144 students across 139 schools were offered the rollout dose, and 20,854 students across 140 schools were offered the catchup doses. RESULTS: High vaccine uptake rates of 80.6%-87.3% were noted with the introduction of the school-based programme, translating to high vaccine coverage of 90.3%-93.4%. Only a small proportion of students (1.5%-1.9% per cohort) opted out. The rate of reported side effects, which were commonly known effects, was low at one in 1000. Among the students who reported side effects, those who received the second vaccine dose did so uneventfully. CONCLUSION High HPV vaccine coverage was achieved after implementation of the school-based immunisation programme. Timely assessment of knowledge lapses and targeted intervention, strong partnerships with stakeholders, constant on-site adaptation and positive social influence contributed to its success. This model can be applied to future school health programmes.
Humans ; Female ; Papillomavirus Vaccines/therapeutic use* ; Human Papillomavirus Viruses ; Papillomavirus Infections/prevention & control* ; Singapore ; Uterine Cervical Neoplasms/epidemiology* ; Vaccination ; Immunization Programs

This study followed up the immune memory after 3-dose revaccination among infants with non-and low-response following primary hepatitis B (HepB) vaccination. About 120 children without self-booster doses were finally included who had anti-HBs<10 mIU/ml (anti-HBs negative) at the time of follow-up, of whom 86 children completed blood sampling and anti-HBs testing. Before the challenge dose, all 86 children were negative for anti-HBs, and the GMC of anti-HBs was<10 mIU/ml. The seropositive conversion rate of anti-HBs was 100% and the GMC of anti-HBs was 886.11 (95%CI: 678.15-1 157.84) mIU/ml after the challenge dose. Compared with those with GMC<7 mIU/ml before the challenge dose, infants with GMC>7 mIU/ml had a higher anti-HBs level after the challenge dose. The β value (95%CI) was 0.82 (0.18-1.46) (P=0.012). Compared with those with GMC<1 000 mIU/ml at primary vaccination, infants with GMC≥1 000 mIU/ml had a higher anti-HBs level after the challenge dose. The β value (95%CI) was 0.78 (0.18-1.38)(P=0.012). The results showed a stronger immune memory was found at 9 years after revaccination among infants with non-and low-response to HepB.
Child ; Humans ; Infant ; Hepatitis B Vaccines ; Immunization, Secondary ; Hepatitis B Surface Antigens ; Immunologic Memory ; Follow-Up Studies ; Vaccination ; Hepatitis B/prevention & control* ; Hepatitis B Antibodies