Displaying publications 1 - 20 of 89 in total

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  1. Kalok A, Loh SYE, Chew KT, Abdul Aziz NH, Shah SA, Ahmad S, et al.
    Vaccine, 2020 02 24;38(9):2183-2189.
    PMID: 32001070 DOI: 10.1016/j.vaccine.2020.01.043
    BACKGROUND: Vaccine hesitancy is a complex behaviour which involves various degrees of indecision about specific vaccines or vaccination uptake. Access to antenatal care had been associated with positive vaccine behavior.

    OBJECTIVE: To determine the prevalence of vaccine hesitancy towards childhood immunisation amongst urban pregnant mothers and the associated socio-demographic factors.

    METHODS: A cross-sectional study was conducted among 1081 women who received antenatal care at a teaching hospital in Kuala Lumpur. Vaccine hesitancy was assessed using the Parent Attitudes about Childhood Vaccines (PACV) Survey in both English and validated Malay versions. The sociodemographic data of the mothers and their partners, source of vaccine information and reasons for hesitancy were analysed.

    RESULTS: Eighty-six (8.0%) pregnant mothers were vaccine hesitant. Ethnicity, religion, number of children, educational level and employment status were significantly associated with vaccine hesitancy. Multivariable analysis showed that a low level of education was the most significant risk factor (p 

  2. Wong LP, Alias H, Hassan J, AbuBakar S
    Vaccine, 2017 10 13;35(43):5912-5917.
    PMID: 28886944 DOI: 10.1016/j.vaccine.2017.08.074
    The aim of this study was to examine the willingness of pregnant women to have prenatal screening for the Zika virus (ZIKV). Secondly, the study also assessed the acceptability of a hypothetical Zika vaccination and its association with the health belief model (HBM) constructs. A cross-sectional study was conducted from 4th October to 11th November 2016, among pregnant women who attended antenatal care at the University Malaya Medical Centre (UMMC), Kuala Lumpur, Malaysia. The majority (81.8%) was willing to be tested for ZIKV and 78% felt that their spouse would be willing to be tested for ZIKV. A total of 94% expressed a willingness to receive a Zika vaccination if available. The participants expressed high perceived benefits of a ZIKV vaccination. Although many have a high perception of the severity of ZIKV, the proportion with a strong perception of their susceptibility to ZIKV was low. In the multivariate analysis of all the HBM constructs, cue-to-action, namely physician recommendation (odds ratio [OR]=2.288; 95% confidence interval [CI] 1.093-4.793) and recommendation from friends or relatives (OR=4.030; 95% CI 1.694-9.587), were significantly associated with a willingness to be vaccinated against ZIKV. The favourable response to a Zika vaccination implies that more research attention has to be given to develop a vaccine against ZIKV. Should the vaccine be available in the future, publicity and healthcare providers would play a vital role in ensuring vaccine uptake among pregnant women.
  3. Palaniappan PA, Mohamed Sukur S, Liow YL, Maniam S, Sherina F, Ahmad N
    Vaccine, 2020 12 03;38(51):8232-8237.
    PMID: 33139134 DOI: 10.1016/j.vaccine.2020.09.066
    BACKGROUND: Haemophilus influenzae (H. influenzae) is a human upper respiratory tract colonizer which causes wide range of disease especially in children<5 years old and in the elderly. Although worldwide incidence in industrialised countries where Hib vaccination is commonly used has dropped sharply since implementation of H. influenzae type b (Hib) vaccination, there is limited data on the disease burden caused by H. influenzae in Malaysia post vaccination era. A change in predominant serotype from type b to non-b serotypes of H. influenzae in invasive diseases was reported worldwide. We investigated the carriage of H. influenzae post vaccination era among 2-4 years old.

    METHODOLOGY: Randomly, we collected 436 oropharyngeal swabs from healthy children aged 2-4 years in 30 registered childcare centres in Kuala Lumpur (August 2018-May 2019). Informed consent and written questionnaires were obtained from parents. H. influenzae was identified by standard microbiological methods. Univariable analysis was carried out to describe variables associated with colonization. All variables with p 

  4. André F
    Vaccine, 2000 Feb 18;18 Suppl 1:S20-2.
    PMID: 10683538
    Asia and Africa have previously been classified as areas of high endemicity for hepatitis B virus (HBV), but in some countries highly effective vaccination programmes have shifted this pattern towards intermediate or low endemicity. Thus, China is now the only country in Asia where HBV endemicity is high. Countries with intermediate endemicity include India, Korea, the Philippines, Taiwan and Thailand, and those with low endemicity include Japan, Pakistan, Bangladesh, Singapore, Sri Lanka and Malaysia. Most countries in Africa have high HBV endemicity, with the exceptions of Tunisia and Morocco, which have intermediate endemicity. Zambia has borderline intermediate/high endemicity. In the Middle East, Bahrain, Iran, Israel and Kuwait are areas of low endemicity, Cyprus, Iraq and the United Arab Emirates have intermediate endemicity, and Egypt, Jordan, Oman, Palestine, Yemen and Saudi Arabia have high endemicity. All of these Middle East countries reach a large proportion of their population with hepatitis B vaccination, which is reducing the infection rate, particularly in Saudi Arabia. The vaccination programme in Taiwan has also greatly reduced the HBV infection rate. Future vaccination programmes must take into account the mode of transmission of HBV, the healthcare infrastructure to deliver vaccination, and the socioeconomic and political factors in each individual country, to determine the most cost-effective way of infection control.
  5. Kim SH, Chung DR, Song JH, Baek JY, Thamlikitkul V, Wang H, et al.
    Vaccine, 2020 08 27;38(38):6065-6073.
    PMID: 31590932 DOI: 10.1016/j.vaccine.2019.09.065
    This study was performed to investigate the serotype distribution and antimicrobial susceptibility of Streptococcus pneumoniae in Asian countries. A prospective surveillance study on S. pneumoniae collected from adult patients (≥50 years old) with invasive pneumococcal disease or community-acquired pneumonia was performed at 66 hospitals in Asian countries (Korea, China, Malaysia, Singapore, the Philippines, and Thailand) in 2012-2017. Serotyping and antimicrobial susceptibility tests of 850 pneumococcal isolates were performed. The proportions of isolates with serotypes covered by 13-valent pneumococcal conjugate vaccine (PCV13) were 37.0% in Korea, 53.4% in China, 77.2% in Malaysia, 35.9% in the Philippines, 68.7% in Singapore, and 60.2% in Thailand. Major serotypes were 19F (10.4%), 19A (10.1%), and 3 (8.5%) in 2012-2017, with different serotype distributions in each country. Macrolide resistance in pneumococci was high (66.8%) and prevalence of multidrug resistance (MDR) also remained high (50.8%). MDR non-PCV13 serotypes such as 11A, 15A, 35B, and 23A have emerged in Asian countries. This study showed the persistent prevalence of 19F and 19A with a noteworthy increase of certain non-PCV13 serotypes in Asian countries. High prevalence of macrolide resistance and MDR was also found in pneumococcal isolates. These data emphasize the need for continued surveillance of pneumococcal epidemiology in Asia in the post-pneumococcal vaccine era.
  6. Bravo LC, Asian Strategic Alliance for Pneumococcal Disease Prevention (ASAP) Working Group
    Vaccine, 2009 Dec 9;27(52):7282-91.
    PMID: 19393708 DOI: 10.1016/j.vaccine.2009.04.046
    This paper represents a collaborative effort by the Asian Strategic Alliance for Pneumococcal Disease Prevention (ASAP) Working Group to collate data on the disease burden due to invasive pneumococcal disease (IPD) in participating Asian countries and territories; namely, Hong Kong, India, Indonesia, Korea, Macau, Malaysia, Pakistan, the Philippines, Singapore, Sri Lanka, Taiwan and Thailand. A review of both published and unpublished data revealed that the incidence of IPD in some countries is well documented by way of large, long-duration studies, while in other countries, much of the available data have been extrapolated from international studies or have come from small population studies of limited geographical coverage. This paper confirms that data regarding the incidence of IPD in Asia are grossly lacking and reinforces the need for urgent and more substantial studies.
  7. Barzaga BN
    Vaccine, 2000 Feb 18;18 Suppl 1:S61-4.
    PMID: 10683551
    A review of the epidemiology of hepatitis A virus (HAV) infection over the last 20 years shows shifting patterns in the prevalence of antibodies to HAV (anti-HAV) throughout South-East Asia and China. A number of countries have shifted from high to moderate and from moderate to low endemicity, with a corresponding increase in the age of exposure from childhood to early adulthood. The changes have resulted from improvements in hygiene, sanitation and the quality of drinking water, reflecting improvements in living standards and socioeconomic progress. In general in the late 1970s and early 1980s, 85-95% of the population of developing countries like the Philippines, Korea, China and Thailand were anti-HAV-positive by age 10-15 years, compared with only about 50% in the more affluent countries like Malaysia and Singapore. In the early 1990s, 85-95% of the population were immune by age 30-40 years in the Philippines, Korea, China and Thailand, and by 50 years of age and above in Malaysia and Singapore. Similar trends were noted in Hong Kong, Taiwan and Japan. Exposure to HAV at a later age may be associated with an increase in hepatitis A morbidity and a greater propensity for outbreaks.
  8. Al-lela OQ, Bahari MB, Al-abbassi MG, Salih MR, Basher AY
    Vaccine, 2012 Jun 6;30(26):3862-6.
    PMID: 22521848 DOI: 10.1016/j.vaccine.2012.04.014
    The immunization status of children is improved by interventions that increase community demand for compulsory and non-compulsory vaccines, one of the most important interventions related to immunization providers. The aim of this study is to evaluate the activities of immunization providers in terms of activities time and cost, to calculate the immunization doses cost, and to determine the immunization dose errors cost. Time-motion and cost analysis study design was used. Five public health clinics in Mosul-Iraq participated in the study. Fifty (50) vaccine doses were required to estimate activities time and cost. Micro-costing method was used; time and cost data were collected for each immunization-related activity performed by the clinic staff. A stopwatch was used to measure the duration of activity interactions between the parents and clinic staff. The immunization service cost was calculated by multiplying the average salary/min by activity time per minute. 528 immunization cards of Iraqi children were scanned to determine the number and the cost of immunization doses errors (extraimmunization doses and invalid doses). The average time for child registration was 6.7 min per each immunization dose, and the physician spent more than 10 min per dose. Nurses needed more than 5 min to complete child vaccination. The total cost of immunization activities was 1.67 US$ per each immunization dose. Measles vaccine (fifth dose) has a lower price (0.42 US$) than all other immunization doses. The cost of a total of 288 invalid doses was 744.55 US$ and the cost of a total of 195 extra immunization doses was 503.85 US$. The time spent on physicians' activities was longer than that spent on registrars' and nurses' activities. Physician total cost was higher than registrar cost and nurse cost. The total immunization cost will increase by about 13.3% owing to dose errors.
  9. Wu DB, Chaiyakunapruk N, Chong HY, Beutels P
    Vaccine, 2015 Mar 30;33(14):1633-58.
    PMID: 25681663 DOI: 10.1016/j.vaccine.2015.01.081
    BACKGROUND: Seven-valent pneumococcal conjugate vaccines (PCV7) have been used in children for more than a decade. Given the observed increase in disease caused by pneumococcal serotypes not covered by PCV7, an increasing number of countries are switching from 7-valent to 10- and 13-valent PCVs ("PCV10" and "PCV13"). Economic evaluations are important tools to inform decisions and price negotiations to make such a switch.
    OBJECTIVE: This review aims to provide a critical assessment of economic evaluations involving PCV10 or PCV13, published since 2006.
    METHODS: We searched Scopus, ISI Web of Science (SCI and SSCI) and Pubmed to retrieve, select and review relevant studies, which were archived between 1st January 2006 and 31st January 2014. The review protocol involved standard extraction of assumptions, methods, results and sponsorships from the original studies.
    RESULTS: Sixty-three economic evaluations on PCVs published since January 2006 were identified. About half of these evaluated PCV10 and/or PCV13, the subject of this review. At current prices, both PCV13 and PCV10 were likely judged preferable to PCV7. However, the combined uncertainty related to price differences, burden of disease, vaccine effectiveness, herd and serotype replacement effects determine the preference base for either PCV10 or PCV13. The pivotal assumptions and results of these analyses also depended on which manufacturer sponsored the study.
    CONCLUSION: A more thorough exploration of uncertainty should be made in future analyses on this subject, as we lack understanding to adequately model herd and serotype replacement effects to reliably predict the population impact of PCVs. The introduction of further improved PCVs in an environment of evolving antibiotic resistance and under the continuing influence of previous PCVs implies that the complexity and data requirements for relevant analyses will further increase. Decision makers using these analyses should not just rely on an analysis from a single manufacturer.
    KEYWORDS: Cost-effectiveness; Cost–benefit; Pneumococcal conjugate vaccine; Streptococcus pneumoniae
    Matched MeSH terms: Heptavalent Pneumococcal Conjugate Vaccine/economics*
  10. Ozawa S, Wonodi C, Babalola O, Ismail T, Bridges J
    Vaccine, 2017 11 07;35(47):6429-6437.
    PMID: 29037575 DOI: 10.1016/j.vaccine.2017.09.079
    BACKGROUND: Understanding and ranking the reasons for low vaccination uptake among parents in northern Nigeria is critical to implement effective policies to save lives and prevent illnesses. This study applies best-worst scaling (BWS) to rank various factors affecting parents' demand for routine childhood immunization.

    METHODS: We conducted a household survey in Nahuche, Zamfara State in northern Nigeria. Nearly two hundred parents with children under age five were asked about their views on 16 factors using a BWS technique. These factors focused on known attributes that influence the demand for childhood immunization, which were identified from a literature review and reviewed by a local advisory board. The survey systematically presented parents with subsets of six factors and asked them to choose which they think are the most and least important in decisions to vaccinate children. We used a sequential best-worst analysis with conditional logistic regression to rank factors.

    RESULTS: The perception that vaccinating a child makes one a good parent was the most important motivation for parents in northern Nigeria to vaccinate children. Statements related to trust and social norms were ranked higher in importance compared to those that highlighted perceived benefits and risks, healthcare service, vaccine information, or opportunity costs. Fathers ranked trust in the media and views of their leaders to be of greatest importance, whereas mothers placed greater importance on social perceptions and norms. Parents of children without routine immunization ranked their trust in local leaders about vaccines higher in considerations, and the media's views lower, compared to parents with children who received routine immunization.

    CONCLUSIONS: Framing immunization messages in the context of good parenting and hearing these messages from trusted information sources may motivate parental uptake of childhood vaccines. These results are useful to policymakers to prioritize resources in order to increase awareness and demand for childhood immunization.

  11. Monath TP, Seligman SJ, Robertson JS, Guy B, Hayes EB, Condit RC, et al.
    Vaccine, 2015 Jan 01;33(1):62-72.
    PMID: 25446819 DOI: 10.1016/j.vaccine.2014.10.004
    The Brighton Collaboration Viral Vector Vaccines Safety Working Group (V3SWG) was formed to evaluate the safety of live, recombinant viral vaccines incorporating genes from heterologous viruses inserted into the backbone of another virus (so-called "chimeric virus vaccines"). Many viral vector vaccines are in advanced clinical trials. The first such vaccine to be approved for marketing (to date in Australia, Thailand, Malaysia, and the Philippines) is a vaccine against the flavivirus, Japanese encephalitis (JE), which employs a licensed vaccine (yellow fever 17D) as a vector. In this vaccine, two envelope proteins (prM-E) of YF 17D virus were exchanged for the corresponding genes of JE virus, with additional attenuating mutations incorporated into the JE gene inserts. Similar vaccines have been constructed by inserting prM-E genes of dengue and West Nile into YF 17D virus and are in late stage clinical studies. The dengue vaccine is, however, more complex in that it requires a mixture of four live vectors each expressing one of the four dengue serotypes. This vaccine has been evaluated in multiple clinical trials. No significant safety concerns have been found. The Phase 3 trials met their endpoints in terms of overall reduction of confirmed dengue fever, and, most importantly a significant reduction in severe dengue and hospitalization due to dengue. However, based on results that have been published so far, efficacy in preventing serotype 2 infection is less than that for the other three serotypes. In the development of these chimeric vaccines, an important series of comparative studies of safety and efficacy were made using the parental YF 17D vaccine virus as a benchmark. In this paper, we use a standardized template describing the key characteristics of the novel flavivirus vaccine vectors, in comparison to the parental YF 17D vaccine. The template facilitates scientific discourse among key stakeholders by increasing the transparency and comparability of information. The Brighton Collaboration V3SWG template may also be useful as a guide to the evaluation of other recombinant viral vector vaccines.
  12. Salmons B, Lim PY, Djurup R, Cardosa J
    Vaccine, 2018 10 29;36(45):6623-6630.
    PMID: 30293762 DOI: 10.1016/j.vaccine.2018.09.062
    A candidate hand, foot, and mouth disease vaccine comprising of human enterovirus A71 (EV-A71) virus-like particles (VLPs) was tested in rabbits to evaluate the potential local and systemic effects of this vaccine. The rabbits received more than double the full human dose and one additional dose according to the n + 1 recommended scheme. The three doses were given mixed with Alhydrogel adjuvant as intramuscular (IM) injections. Vaccinations were well-tolerated, with no indication of overt toxicity in any parameter observed. An EV-A71 specific immune response in the form of antibodies that specifically reacted with the virus capsid proteins VP1 and VP0, the complete VLP, and EV-A71 viruses of different subgenotypes to that of the vaccine could be demonstrated. A boosting effect in the form of higher EV-A71 specific antibody titers was observed after the subsequent doses, and these enhanced titers were shown to be statistically significant in one-way ANOVA analyses. Fortnightly intramuscular administration of EV-A71 VLP vaccine did not result in any test article-related changes in immunotoxicity as defined by increased serum IL-6, and in general IL-6 concentrations remained below the lower limit of quantitation for the majority of animals throughout the study. Although increased indicators of inflammation at the injection site were observed in animals sacrificed immediately after the last vaccination, these largely reversed at the end of the recovery phase. No findings suggestive of systemic or delayed toxicity were recorded in this independently conducted study. In conclusion, repeated IM administration of the EV-A71 VLP vaccine were locally and systemically well-tolerated in rabbits and immunogenic, supporting the clinical development of the vaccine.
  13. Reed Z, Cardosa MJ
    Vaccine, 2016 06 03;34(26):2967-2970.
    PMID: 26973065 DOI: 10.1016/j.vaccine.2016.02.077
    Although outbreaks of Hand, Foot, and Mouth Disease (HFMD) in young children have long been recognized worldwide, the occurrence of rare and life-threatening neurological, respiratory, and cardiac complications has propelled this common condition into the spotlight as a major public health problem in the affected countries. Various enteroviruses cause HFMD, but the severe complications have been mostly associated with enterovirus 71 (EV71). Medical treatment is supportive and measures to interrupt transmission have been challenging to implement. Preventive vaccines could have an important clinical impact, especially among children younger than 3 years old who are most susceptible to the neurological complications. Several groups in the highly affected Asia-Pacific region are working towards vaccines against EV71 and some candidates have progressed to late-stage clinical trials with two vaccines recently reported to have been approved by the regulatory authorities in China. This report summarizes current issues and progress in the development of vaccines against EV71.
  14. Lim PY, Hickey AC, Jamiluddin MF, Hamid S, Kramer J, Santos R, et al.
    Vaccine, 2015 Nov 4;33(44):6017-24.
    PMID: 26271825 DOI: 10.1016/j.vaccine.2015.05.108
    A vaccine against human enterovirus 71 (EV-A71) is urgently needed to combat outbreaks of EV-A71 and in particular, the serious neurological complications that manifest during these outbreaks. In this study, an EV-A71 virus-like-particle (VLP) based on a B5 subgenogroup (EV-A71-B5 VLP) was generated using an insect cell/baculovirus platform. Biochemical analysis demonstrated that the purified VLP had a highly native procapsid structure and initial studies in vivo demonstrated that the VLPs were immunogenic in mice. The impact of VLP immunization on infection was examined in non-human primates using a VLP prime-boost strategy prior to EV-A71 challenge. Rhesus macaques were immunized on day 0 and day 21 with VLPs (100 μg/dose) containing adjuvant or with adjuvant alone (controls), and were challenged with EV-A71 on day 42. Complete blood counts, serum chemistry, magnetic resonance imaging (MRI) scans, and histopathology results were mostly normal in vaccinated and control animals after virus challenge demonstrating that the fatal EV-A71-B3 clinical isolate used in this study was not highly virulent in rhesus macaques. Viral genome and/or infectious virus were detected in blood, spleen or brain of two of three control animals, but not in any specimens from the vaccinated animals, indicating that VLP immunization prevented systemic spread of EV-A71 in rhesus macaques. High levels of IgM and IgG were detected in VLP-vaccinated animals and these responses were highly specific for EV-A71 particles and capsid proteins. Serum from vaccinated animals also exhibited similar neutralizing activity against different subgenogroups of EV-A71 demonstrating that the VLPs induced cross-neutralizing antibodies. In conclusion, our EV-A71-B5 VLP is safe, highly immunogenic, and prevents systemic EV-A71-B3 infection in nonhuman primates making it a viable attractive vaccine candidate for EV-A71.
  15. Ng SS, Hutubessy R, Chaiyakunapruk N
    Vaccine, 2018 05 03;36(19):2529-2544.
    PMID: 29625764 DOI: 10.1016/j.vaccine.2018.03.024
    BACKGROUND: The success of human papillomavirus (HPV) national immunization program depends on effective strategies in optimizing the uptake of HPV vaccine. Given the increasing number of economic evaluations, this review was conducted to update the economic evidence on HPV vaccination, by focusing on: (i) 9-valent vaccine compared to bi- or quadrivalent vaccine; (ii) gender-neutral vaccination compared to female only vaccination; and (iii) multiple age cohort immunization compared to single age cohort immunization.

    METHODS: Searches were performed until June 2016 using 4 databases: PubMed; Embase; Cochrane Library; and LILACS. The combined WHO, Drummond and CHEERS checklist were used to evaluate the quality of included studies.

    RESULTS: Thirty-four studies were included in the review and most of them were conducted in high-income countries. The inclusion of adolescent boys in vaccination program was found to be cost-effective if vaccine price and coverage was low. When coverage for female was above 75%, gender-neutral vaccination was less cost-effective than when targeting only girls aged 9-18 years. Current evidence does not show conclusive proof of greater cost-effectiveness of 9-valent vaccine compared to the older HPV vaccines as the price for 9-valent vaccine was still uncertain. Multicohort immunization strategy was cost-effective in the age range 9-14 years but the upper age limit at which vaccination was no longer cost-effective needs to be further investigated. Key influential parameters identified were duration of vaccine protection, vaccine price, coverage, and discounting rates.

    CONCLUSIONS: These findings are expected to support policy-makers in making recommendations for HPV immunization programs on either switching to the 9-valent vaccine or inclusion of adolescent boys' vaccination or extending the age of vaccination.

  16. Kotirum S, Vutipongsatorn N, Kongpakwattana K, Hutubessy R, Chaiyakunapruk N
    Vaccine, 2017 06 08;35(26):3364-3386.
    PMID: 28504193 DOI: 10.1016/j.vaccine.2017.04.051
    INTRODUCTION: World Health Organization (WHO) recommends Rotavirus vaccines to prevent and control rotavirus infections. Economic evaluations (EE) have been considered to support decision making of national policy. Summarizing global experience of the economic value of rotavirus vaccines is crucial in order to encourage global WHO recommendations for vaccine uptake. Therefore, a systematic review of economic evaluations of rotavirus vaccine was conducted.

    METHODS: We searched Medline, Embase, NHS EED, EconLit, CEA Registry, SciELO, LILACS, CABI-Global Health Database, Popline, World Bank - e-Library, and WHOLIS. Full economic evaluations studies, published from inception to November 2015, evaluating Rotavirus vaccines preventing Rotavirus infections were included. The methods, assumptions, results and conclusions of the included studies were extracted and appraised using WHO guide for standardization of EE of immunization programs.

    RESULTS: 104 relevant studies were included. The majority of studies were conducted in high-income countries. Cost-utility analysis was mostly reported in many studies using incremental cost-effectiveness ratio per DALY averted or QALY gained. Incremental cost per QALY gained was used in many studies from high-income countries. Mass routine vaccination against rotavirus provided the ICERs ranging from cost-saving to highly cost-effective in comparison to no vaccination among low-income countries. Among middle-income countries, vaccination offered the ICERs ranging from cost-saving to cost-effective. Due to low- or no subsidized price of rotavirus vaccines from external funders, being not cost-effective was reported in some high-income settings.

    CONCLUSION: Mass vaccination against rotavirus was generally found to be cost-effective, particularly in low- and middle-income settings according to the external subsidization of vaccine price. On the other hand, it may not be a cost-effective intervention at market price in some high-income settings. This systematic review provides supporting information to health policy-makers and health professionals when considering rotavirus vaccination as a national program.

  17. Lee MHP, Tan CW, Tee HK, Ong KC, Sam IC, Chan YF
    Vaccine, 2021 03 19;39(12):1708-1720.
    PMID: 33640144 DOI: 10.1016/j.vaccine.2021.02.024
    Enterovirus A71 (EV-A71) causes hand, foot and mouth disease (HFMD) in young children. It is associated with severe neurological complications and death. This study aims to develop a live-attenuated vaccine by codon deoptimization (CD) and codon-pair deoptimization (CPD) of EV-A71. CD is generated by introducing the least preferred codons for amino acids while CPD increases the presence of underrepresented codon pairs in the specific genes. CD and CPD chimeras were generated by synonymous mutations at the VP2, VP3, VP1 and 2A gene regions, designated as XYZ. All twelve deoptimized viruses were viable with similar replication kinetics, but the plaque sizes were inversely proportional to the level of deoptimization. All the deoptimized viruses showed attenuated growth in vitro with reduced viral protein expression at 48 h and lower viral RNA at 39 °C. Six-week-old ICR mice were immunized intraperitoneally with selected CD and CPD X and XY vaccine candidates covering the VP2-VP3 and VP2-VP3-VP1 genes, respectively. All vaccine candidates elicited high anti-EV-A71 IgG levels similar to wild-type (WT) EV-A71. The CD X and CPD X vaccines produced robust neutralizing antibodies but not the CD XY and CPD XY. On lethal challenge, offspring of mice immunized with WT, CD X and CPD X were fully protected, but the CD XY- and CPD XY-vaccinated mice had delayed symptoms and eventually died. Similarly, active immunization of 1-day-old suckling mice with CD X, CPD X and CD XY vaccine candidates provided complete immune protection but CPD XY only protected 40% of the challenged mice. Histology of the muscles from CD X- and CPD X-vaccinated mice showed minimal pathology compared to extensive inflammation in the post-challenged mock-vaccinated mice. Overall, we demonstrated that the CD X and CPD X elicited good neutralizing antibodies, conferred immune protection and are promising live-attenuated vaccine candidates for EV-A71.
  18. Sam IC, Ahmad Jaafar N, Wong LP, Nathan AM, de Bruyne JA, Chan YF
    Vaccine, 2021 05 21;39(22):2983-2988.
    PMID: 33931252 DOI: 10.1016/j.vaccine.2021.04.010
    BACKGROUND: Acute respiratory infections (ARI) are a major cause of morbidity and mortality in Malaysian children 
  19. Richardson A, Morris DE, Clarke SC
    Vaccine, 2014 Jul 16;32(33):4119-23.
    PMID: 24907487 DOI: 10.1016/j.vaccine.2014.05.062
    Streptococcus pneumoniae, Haemophilus influenzae type b and Neisseria meningitidis are leading causes of vaccine-preventable diseases such as meningitis, sepsis and pneumonia. Although there has been much progress in the introduction of vaccines against these pathogens, access to vaccines remains elusive in some countries. This review highlights the current S. pneumoniae, H. influenzae type b, and N. meningitidis immunization schedules in the 10 countries belonging to the Association of Southeast Asian Nations (ASEAN). Epidemiologic studies may be useful for informing vaccine policy in these countries, particularly when determining the cost-effectiveness of introducing new vaccines.
  20. Jauneikaite E, Jefferies JM, Hibberd ML, Clarke SC
    Vaccine, 2012 May 21;30(24):3503-14.
    PMID: 22475858 DOI: 10.1016/j.vaccine.2012.03.066
    BACKGROUND: Streptococcus pneumoniae is a major cause of bacterial infections resulting in significant morbidity and mortality worldwide. Currently, up to 13 serotypes are included in pneumococcal conjugate vaccines (PCVs). However, the serotype formulation of these vaccines was initially designed to protect children against serotypes most commonly causing invasive disease in North America, and may not reflect the serotype distribution across the world. Data regarding pneumococcal epidemiology from the other parts of the world, in particular South East Asia, has not been reviewed.
    METHODS: This systematic literature review analyses published serotype data regarding S. pneumoniae isolates from South East Asian countries (defined as countries belonging to the Association of South East Asian Nations, ASEAN): Brunei, Cambodia, Indonesia, Laos, Malaysia, Myanmar, Philippines, Singapore, Thailand and Vietnam up to 3rd of March 2012.
    RESULTS: Analysis of data from six ASEAN countries, from which information on pneumococcal serotypes was available, showed that the most common disease causing serotypes (in rank order) were 19F, 23F, 14, 6B, 1, 19A and 3. Serotype distribution of pneumococcal isolates was similar across the ASEAN region. Serotype level data was more commonly reported for pneumococcal isolates causing invasive pneumococcal disease than for those from non-invasive disease. Studies from Malaysia, Thailand and Singapore contributed the largest proportion of pneumococcal isolates, and serotype data, when compared to other ASEAN countries.
    CONCLUSION: This review demonstrates that the majority of IPD causing serotypes in SE Asia are included in currently licensed PCVs. However, PCV's are included in the routine childhood immunisation schedule of only one of the ten countries included in this analysis. Our findings demonstrate the scarcity of information available on serotype prevalence and distribution of pneumococci in SE Asia.
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