Search

Heterologous Sinovac-CoronaVac booster(s) in 12-17-year-olds who had a moderate/severe reaction to Pfizer-BNT162b2 mRNA vaccine was found to safe with no serious adverse events reported. In those primed with 1 dose of Pfizer-BNT162b2 vaccine, subsequent boosters with 2 doses of Sinovac-CoronaVac vaccines achieved neutralizing antibody levels which were comparable to those who had received 2 doses of Pfizer-BNT162b2 vaccines followed by 1 dose of Sinovac-CoronaVac vaccination. Adolescents with 1 Pfizer-BNT162b2 followed by 2 Sinovac-CoronaVac vaccines developed T-cell responses against broad peptides including membrane, nucleoprotein 1 and 2 but levels were highest for Spike protein and lasted until day 150 post-vaccination., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: [Chia-Yin CHong reports financial support was provided by Government of Singapore Ministry of Health. Chee-Fu Yung reports financial support was provided by National Medical Research Council.]., (Copyright © 2024. Published by Elsevier India Pvt Ltd.)

Pertussis vaccination (Tdap -Tetanus-diphtheria-acellular pertussis) for pregnant women has been recommended since November 2017 in Singapore. In this prospective test-negative case-control study from 2018 to 2019, we aimed to evaluate vaccine effectiveness (VE) against pertussis infection and pertussis-related intensive care unit (ICU) admission according to Tdap (Tetanus-diphtheria-acellular pertussis) during pregnancy and/or infant pertussis vaccination. A total of 58 children (26 cases, 32 controls) were recruited with 4 ICU admissions. The median age was 3 months (interquartile range [IQR] 1.50-4.56 months). Overall, 25.9 % of mothers had received antenatal Tdap vaccination and 43.1 % of infants received pertussis vaccination, majority only 1 dose. Tdap in pregnancy alone without infant vaccine or with 0-1 infant dose had a VE of 97.62 % (95 % confidence interval [CI] 53.25-99.88 %), 98.17 % (95 %CI 66.61-99.9 %) respectively, against pertussis infection and 71.9 % (95 %CI 0.0-98.64), 75.86 % (95 % CI 0.0-98.78) respectively, against ICU admissions. Conclusion: Maternal Tdap vaccination was highly protective against infant pertussis and should be routinely recommended for all pregnant women., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

In Asia, the public health burden of influenza is significant despite the existence of efficacious influenza vaccines. Annual seasonal influenza vaccination can reduce the incidence of influenza significantly, yet influenza vaccination coverage remains low in this part of the world. As a densely populated region with varying climatic zones and a larger proportion of developing countries compared to the West, Asia is at increased risk of influenza. To provide a more comprehensive and nuanced understanding of the Asian region, the key objective of this systematic review is to examine the determinants of vaccination uptake in Asia, beyond that of existing studies that have largely been western-centric. We carried out a systematic review of peer-reviewed scientific research, examining the key determinants, acceptance and uptake of influenza vaccinations across Asia. A comprehensive search strategy was defined to capture studies that met the inclusion criteria of articles published in English, from 2008 to 2018, focusing on adult populations within Asia. A total of 83 relevant studies were appraised in this review. Analyses of the extant data confirmed that vaccination rates within Asia are low, and that most countries lack scientific research on vaccination behaviours. Studies were categorised into four different population groups: healthcare workers, high risk groups, general population and uniform groups. The motivators and deterrents for vaccine uptake varied according to population groups and characteristics. Both general populations and healthcare workers were concerned with vaccine safety and efficacy, and recommendations from health authorities were influential in vaccine uptake within the other populations. The findings suggest that further research is needed within a broader range of Asian countries to garner greater in-depth knowledge of vaccination behaviours in the region. In particular, influenza vaccination programs within Asia should focus on improving engagement more effectively, through greater relatability and transparency of data when educating the public., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Background: Influenza vaccine acceptance among healthcare workers (HCWs) is a worldwide problem, but relatively little research has focussed on Asia, including Singapore. Despite widespread access and recommendations from public health authorities, influenza vaccine uptake remains suboptimal among HCWs., Methods: Our qualitative study used focus group discussions to identify and explain factors limiting influenza vaccine acceptance among HCWs in Singapore. A total of 73 doctors, nurses, allied health and ancillary staff across three public hospitals were included., Results: Challenges identified include a fear of contracting influenza from vaccination exacerbated by negative anecdotes regarding vaccine safety and efficacy, distrust of published efficacy data, uncertainty regarding relevance of existing data for Singapore, reluctance to introduce chemicals or overmedicate, pain from injection, low risk attributed to influenza and limited awareness of influenza transmission with a preference for alternatives in patient protection. Differences in attitudes were observed across vocational groups. Lack of overt promotion by hospital leadership in some institutions, perceived vaccine hesitancy among doctors, access, and work culture that implicitly encourages working through illness were further barriers., Conclusion: Our findings highlight a combination of misperceptions about influenza vaccination and cognitive biases at the individual level, and challenges at the institutional level limiting uptake. Findings indicate an urgent need to provide targeted education and communication. Rather than providing more data, we recommend a widely-disseminated, locally-compiled synthesis addressing specific concerns of hesitant HCWs. Tailoring interventions to specific vocational groups should be considered. Institutional norms and culture may have a powerful influence in setting default behaviours: more effort is needed in improving influenza vaccine promotion and priority at some institutions, integrating vaccine-related communication with other infection control communication and addressing influenza vaccine hesitancy among doctors as a priority. Finally, further study of strategies to address cognitive biases affecting influenza vaccine acceptance in Singapore is desirable., (Copyright © 2018. Published by Elsevier Ltd.)

Introduction: Pertussis causes the highest complication rates and deaths in the infant group. Our study explored risk factors for ICU/high dependency (HD) admissions and intubation/non-invasive ventilation (NIV)., Methods: A retrospective review of pertussis admissions over 10 years from 2007 to 2016 was done at KK Women's and Children's Hospital, Singapore. To understand risk factors for severe pertussis infection, we compared cases requiring ICU/HD care with controls admitted to the general ward. Risk factors for intubation/NIV were also studied. Vaccine efficacy for protection against ICU/HD admission or intubation/NIV was also calculated., Results: There were 200 pertussis patients with a median age of 2.75 months. Sixty-one % were ≤3 months and 14.5% were <6 weeks old. Majority of patients (77%) had no prior pertussis vaccination. After removing 3 patients with missing vaccination records, 20 cases were compared with 177 controls. On univariate analysis, risk factors for ICU/HD admission comprised: Age ≤3 months, contact history, underlying co-morbidity, prematurity, absent DTaP vaccination, lymphocytosis, hyperleukocytosis (wbc ≥50×10 9 /L), thrombocytosis (platelet ≥500×10 9 /L), and pneumonia. Multivariate analysis revealed that age ≤3 months (OR 40, 95% CI 4.57-1111.11, p=.007), co-morbidity (OR 8.46 (95% CI 1.47-56.89, p=.019), pneumonia (OR 18.08, 95% CI 3.22-132.15, p=.002), white cell count (OR 1.07, 95% CI 1.01-1.14, p=.023) and cyanosis (OR 5.09, 95% CI 1.31-24.71, p=.026) were risk factors for ICU/HD admission. Prior DTaP vaccination had a vaccine effectiveness of 86.5% in preventing ICU/HD admission and 82.1% in preventing intubation/NIV., Conclusions: As the majority of pertussis patients were infants ≤3 months old who are at high risk for ICU/HD admission and intubation/NIV, prevention is key to reducing pertussis morbidity. Even though not statistically significant, DTaP vaccination had a role in preventing ICU/HD admission and intubation/NIV., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Introduction: From 2011 to 2012, we received an unexpectedly high number of reports of suppurative lymphadenitis following administration of a BCG vaccine used in our childhood vaccination programme in Singapore. We sought to determine the local incidence rates of BCG-associated suppurative lymphadenitis across the 2009 to 2012 vaccinated cohorts, and to analyse the potential factors contributing to this outbreak., Methods: Reports of lymphadenitis following BCG vaccination from an AEFI active surveillance system at the KK Women's and Children's Hospital (KKH) and passive surveillance data from other healthcare institutions were reviewed. All valid reports received from January 2009 to December 2013 involving neonates vaccinated with the BCG vaccine in 2009 to 2012 that met case definitions were included in our analysis. Details of the demographics and vaccination history of the child, and statistics from the local vaccination programme were also obtained. Potential contributory factors were selected for further investigation based on a literature review of similar outbreaks overseas., Results: We identified 283 cases of lymphadenitis, of which 76% were suppurative. A spike in suppurative lymphadenitis cases was seen in the 2011 vaccinated cohort, with an incidence rate of 3.16 per 1000 vaccinees, as compared to 0.71 to 0.85 per 1000 in the 2009, 2010 and 2012 cohorts. Our investigations identified the likely cause of the outbreak to be batch-related, arising from manufacturing issues encountered by the manufacturer, after ruling out vaccine administration-related and host-related factors., Conclusions: The three-fold spike in BCG-associated suppurative lymphadenitis cases observed in the 2011 vaccinated cohort, possibly due to batch-to-batch variation of the vaccine, highlights that manufacturing controls can continue to be a challenge. Development of a more sensitive assay to test the reactogenicity of the BCG vaccine may help reduce the occurrence of such outbreaks and improve public confidence in the nation's vaccination programme., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Introduction: In Singapore, reporting of adverse events following immunization (AEFI) was historically passive. In 2009, Health Sciences Authority collaborated with KK Women's and Children's Hospital to perform active surveillance for AEFI. We report the methodology and initial findings of this surveillance following childhood vaccines., Methods: From April 2010 to March 2012, we screened all paediatric admissions for possible relationships to vaccination, excluding elective admissions, and performed causality assessment for each case using standardized definitions for certain, probable, possible and unlikely. Baseline demographics, data on implicated vaccines and clinical details including severity and outcomes were collected. Total hospital admissions were used to calculate rates of AEFI., Results: We screened 45,571 (80%) of 56,526 admissions, and evaluated 1988 (4.4%) children. Median age at presentation was 3.1 months, while median interval from vaccination to symptom onset was 6 days. There were 311 (15.6%) children with AEFI that were considered possibly, probably or certainly associated with vaccines. However, 98.8% recovered without any long-term sequelae. The hospital-based active surveillance of AEFI enabled the detection of a 5-fold increase (95% CI 1.2-33.1) in BCG-associated regional lymphadenitis in April 2010, which triggered follow-up safety analysis to guide public health advice., Conclusions: Hospital-based active surveillance can enhance signal detection and follow-up investigations of AEFI. Subsequently, public health bodies are better equipped to maintain public confidence in vaccination programmes and physicians are able to provide relevant advice to parents. It also allows for a better understanding of risk-benefit ratios of specific vaccines and aids the generation of public health vaccination policy., (Copyright © 2014 Elsevier Ltd. All rights reserved.)