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Lim AH, Ab Rahman N, Ong SM, Paraja J, Rashid R, Parmar IS, Dahlan SN, Tan ZSS, Bohari I, Peariasamy KM, Sivasampu S. Evaluation of BNT162b2 vaccine effectiveness in Malaysia: test negative case-control study. Vaccine 2022; 40:5675-5682. [PMID: 36030123 PMCID: PMC9399819 DOI: 10.1016/j.vaccine.2022.08.032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Revised: 07/13/2022] [Accepted: 08/15/2022] [Indexed: 12/01/2022]
Abstract
There is a notable lack of vaccine effectiveness studies using test-negative case-controlled approach in low- and middle-income countries which have different logistic, demographic and socio-economic conditions from high-income countries. We aimed to estimate the effectiveness of BNT162b2 vaccine against COVID-19 infection over time, intensive care unit admission, severe or critical disease and death due to COVID-19. This study was conducted in the resident population of Labuan aged ≥18 years who had been tested for SARS-CoV-2 by Reverse-Transcriptase Polymerase Chain Reaction between 1 March 2021 and 31 October 2021. We used a test-negative case-control design where 2644 pairs of cases and controls were matched by age, sex, testing date, nationality and testing reason. Analysis was stratified by age group to estimate age effect (<60 years and ≥60 years). Of 22217 individuals tested by Reverse-Transcriptase Polymerase Chain Reaction, 5100 were positive for SARS-CoV-2 and aged 18 years and above. Overall vaccine effectiveness ≥ 14 days after the second dose was 65.2% (95% CI: 59.8–69.9%) against COVID-19 infection, 92.5% (95% CI: 72.3–98.8%) against intensive care unit admission, and 96.5% (95% CI: 82.3–99.8%) against COVID-19 deaths. Among infected individuals, vaccine effectiveness was 79.2% (95% CI: 42.3–94.1%) in preventing severe or critical disease due to COVID-19. Vaccine effectiveness for ≥60 years was 72.3% (95% CI: 53.4–83.9%) in fully vaccinated individuals, higher than 64.8% (95% CI: 49.3–59.1%) for those <60 years. Two doses of BNT162b2 were highly effective against COVID-19 infection, severe or critical disease, intensive care unit admission and death due to COVID-19. This study addresses a gap in literature on BNT162b2 vaccine effectiveness in low- and middle-income populations and demonstrates the feasibility of such a study design in a resource limited setting while supporting evidence of waning immunity.
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Affiliation(s)
- Audrey Huili Lim
- Institute for Clinical Research, National Institutes of Health, Ministry of Health, Malaysia.
| | - Norazida Ab Rahman
- Institute for Clinical Research, National Institutes of Health, Ministry of Health, Malaysia
| | - Su Miin Ong
- Institute for Clinical Research, National Institutes of Health, Ministry of Health, Malaysia
| | | | - Rahmah Rashid
- Labuan State Health Department, Ministry of Health, Malaysia
| | | | | | | | - Ismuni Bohari
- Labuan State Health Department, Ministry of Health, Malaysia
| | - Kalaiarasu M Peariasamy
- Institute for Clinical Research, National Institutes of Health, Ministry of Health, Malaysia
| | - Sheamini Sivasampu
- Institute for Clinical Research, National Institutes of Health, Ministry of Health, Malaysia
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Ciocănea-Teodorescu I, Nason M, Sjölander A, Gabriel EE. Adjustment for Disease Severity in the Test-Negative Study Design. Am J Epidemiol 2021; 190:1882-1889. [PMID: 33728441 DOI: 10.1093/aje/kwab066] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 03/11/2021] [Accepted: 03/11/2021] [Indexed: 11/14/2022] Open
Abstract
The test-negative study design is often used to estimate vaccine effectiveness in influenza studies, but it has also been proposed in the context of other infectious diseases, such as cholera, dengue, or Ebola. It was introduced as a variation of the case-control design, in an attempt to reduce confounding bias due to health-care-seeking behavior, and has quickly gained popularity because of its logistic advantages. However, examination of the directed acyclic graphs that describe the test-negative design reveals that without strong assumptions, the estimated odds ratio derived under this sampling mechanism is not collapsible over the selection variable, such that the results obtained for the sampled individuals cannot be generalized to the whole population. In this paper, we show that adjustment for severity of disease can reduce this bias and, under certain assumptions, makes it possible to unbiasedly estimate a causal odds ratio. We support our findings with extensive simulations and discuss them in the context of recently published cholera test-negative studies of the effectiveness of cholera vaccines.
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Fustec B, Phanitchat T, Hoq MI, Aromseree S, Pientong C, Thaewnongiew K, Ekalaksananan T, Bangs MJ, Corbel V, Alexander N, Overgaard HJ. Complex relationships between Aedes vectors, socio-economics and dengue transmission-Lessons learned from a case-control study in northeastern Thailand. PLoS Negl Trop Dis 2020; 14:e0008703. [PMID: 33001972 PMCID: PMC7553337 DOI: 10.1371/journal.pntd.0008703] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2020] [Revised: 10/13/2020] [Accepted: 08/12/2020] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND/OBJECTIVES Dengue fever is an important public health concern in most tropical and subtropical countries, and its prevention and control rest on vector surveillance and control. However, many aspects of dengue epidemiology remain unclear; in particular, the relationship between Aedes vector abundance and dengue transmission risk. This study aims to identify entomological and immunological indices capable of discriminating between dengue case and control (non-case) houses, based on the assessment of candidate indices, as well as individual and household characteristics, as potential risk factors for acquiring dengue infection. METHODS This prospective, hospital-based, case-control study was conducted in northeastern Thailand between June 2016 and August 2019. Immature and adult stage Aedes were collected at the houses of case and control patients, recruited from district hospitals, and at patients' neighboring houses. Blood samples were tested by RDT and PCR to detect dengue cases, and were processed with the Nterm-34 kDa salivary peptide to measure the human immune response to Aedes bites. Socioeconomic status, and other individual and household characteristics were analyzed as potential risk factors for dengue. RESULTS Study findings showed complex relationships between entomological indices and dengue risk. The presence of DENV-infected Aedes at the patient house was associated with 4.2-fold higher odds of dengue. On the other hand, Aedes presence (irrespective of infectious status) in the patient's house was negatively associated with dengue. In addition, the human immune response to Aedes bites, was higher in control than in case patients and Aedes adult abundance and immature indices were higher in control than in case houses at the household and the neighboring level. Multivariable analysis showed that children aged 10-14 years old and those aged 15-25 years old had respectively 4.5-fold and 2.9-fold higher odds of dengue infection than those older than 25 years. CONCLUSION DENV infection in female Aedes at the house level was positively associated with dengue infection, while adult Aedes presence in the household was negatively associated. This study highlights the potential benefit of monitoring dengue viruses in Aedes vectors. Our findings suggest that monitoring the presence of DENV-infected Aedes mosquitoes could be a better indicator of dengue risk than the traditional immature entomological indices.
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Affiliation(s)
- Benedicte Fustec
- University of Montpellier, Montpellier, France
- Department of Microbiology, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
- Institut de Recherche pour le Developpement, Montpellier, France
| | - Thipruethai Phanitchat
- Department of Medical Entomology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Mohammad Injamul Hoq
- School of Public Health, Epidemiology and Social Medicine at the Institute of Medicine, University of Gothenburg, Gothenburg, Sweden
| | - Sirinart Aromseree
- Department of Microbiology, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
- HPV & EBV and Carcinogenesis Research Group, Khon Kaen University, Khon Kaen, Thailand
| | - Chamsai Pientong
- Department of Microbiology, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
- HPV & EBV and Carcinogenesis Research Group, Khon Kaen University, Khon Kaen, Thailand
| | | | - Tipaya Ekalaksananan
- Department of Microbiology, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
- HPV & EBV and Carcinogenesis Research Group, Khon Kaen University, Khon Kaen, Thailand
| | - Michael J. Bangs
- Public Health & Malaria Control, PT Freeport Indonesia/International SOS, Mimika, Papua, Indonesia
- Department of Entomology, Faculty of Agriculture, Kasetsart University, Bangkok, Thailand
| | - Vincent Corbel
- University of Montpellier, Montpellier, France
- Institut de Recherche pour le Developpement, Montpellier, France
| | - Neal Alexander
- MRC Tropical Epidemiology Group, London School of Hygiene and Tropical Medicine, London, United Kingdom
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Kabir KMA, Hagishima A, Tanimoto J. Hypothetical assessment of efficiency, willingness-to-accept and willingness-to-pay for dengue vaccine and treatment: a contingent valuation survey in Bangladesh. Hum Vaccin Immunother 2020; 17:773-784. [PMID: 32820987 DOI: 10.1080/21645515.2020.1796424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
In 2019, Bangladesh has grappled with a record-breaking surge in dengue fever, experiencing the highest number of dengue cases since the year 2000. Together, the intensification of dengue fever combined with a lack of dengue vaccines and appropriate medicines is expected to further the public and government's interests in appropriate and potential dengue vaccines to control the epidemic. We considered people's characteristics, dengue experience, and knowledge to assess their willingness-to-accept (WTA) and willingness-to-pay (WTP) for a hypothetical dengue vaccine and ex-post treatment in Bangladesh (June-July 2019). This study implemented a contingent valuation (CV) method with 3,251 respondents in 10 different locations of Bangladesh. All respondents participated in a hypothetical dengue vaccine scenario consisting of 65% (vaccine A), 80% (vaccine B), and 95% (vaccine C) effectiveness levels with three doses of each vaccine and ex-post dengue treatment. Around 71.2% of respondents were willing to pay for at least one of the hypothetical vaccines: A, B, or C. The average WTPs of the three vaccines amounted to US$ 47.0, US$ 66.0, and US$ 89.0, which were defined as the total cost of the doses necessary to obtain immunity. In Bangladesh, there is a significant demand for low-priced dengue vaccines, which was proven by people's higher acceptance of vaccination practices. Though dengue vaccines are not yet available in Bangladesh, this study provides significant support that both the government and private sectors should work together to develop a reliable and affordable dengue vaccine.
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Affiliation(s)
- K M Ariful Kabir
- Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga-shi, Fukuoka, Japan.,Department of Mathematics, Bangladesh University of Engineering and Technology, Dhaka, Bangladesh
| | - Aya Hagishima
- Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga-shi, Fukuoka, Japan.,Faculty of Engineering Sciences, Kyushu University, Kasuga-shi, Fukuoka, Japan
| | - Jun Tanimoto
- Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga-shi, Fukuoka, Japan.,Faculty of Engineering Sciences, Kyushu University, Kasuga-shi, Fukuoka, Japan
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