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A study by the international Global Burden of Disease Study (GBD) collaboration (which includes researchers from OUCRU), published in The Lancet, analyzed each country’s progress toward achieving the United Nation’s health-related Sustainable Development Goals (SDG) targets by creating an overall SDG Index score. Countries were then ranked by their scores to show which nations are closest to achieving the targets, and Vietnam stands out as having achieved significant progress.
African leadership in brain diplomacy: The Yaoundé declaration advances the global brain economy playbook for better brain Health.
Africa, the world's second-largest continent is home to 1.5 billion people, accounting for nearly 20% of the global population, (60% under age 25). By 2050, Africa's population will be 2.5 billion, and by 2035, more young Africans will be entering the workforce each year than in the rest of the world combined. Africa also hosts a rich social, cultural, and geopolitical diversity across its 5 geopolitical zones covering 54 countries. It is the most genetically, culturally, and linguistically diverse region on the planet. However, Africa's contribution to the global economy could be more significant if it urgently embraces the brain economy and leads in the development of new methodologies and approaches which can be exported around the world. In this paper, we explain our strategy to advance the Yaoundé Declaration for the Brain Economy, Brain Health, and Brain Capital. The Declaration has been endorsed by Cameroon's President, His Excellency Paul Biya, and demonstrates African leadership in global brain and society innovations, laying out a roadmap for how Africa can outcompete other economies by deftly deploying brain science-inspired policies and investments. We outline a new economic approach for African jobs, economic growth, sustainability, resilience, health, and well-being. The brain economy offers a broader framework than the current sustainable development goals (SDG) agenda. The Yaoundé Declaration is trans-disciplinary and cross-cutting across sectors: 32 sitting members of government from different sectors having co-authored this paper. It aligns with many aspects of the United Nations Pact for the Future and can accelerate the SDG.
Sociodemographic influences on substance use in psychosis in an African cohort.
BackgroundSubstance use is common among individuals with psychotic disorders, but limited research exists on the variations in substance use across countries in Africa. This study aims to investigate the frequency of alcohol, tobacco, cannabis, and khat consumption in individuals with bipolar disorder (BD) and schizophrenia (SCZ) across four African countries: South Africa, Ethiopia, Kenya, and Uganda.MethodsWe utilized data from the Neuropsychiatric Genetics of African Populations-Psychosis project, a large case-control study which will soon have genetic data on over 42,000 participants, half with psychosis. Information on substance use was collected using the Alcohol, Smoking and Substance Involvement Screening Test v3 (ASSIST). The outcome was categorized into never (lifetime usage, no), irregular usage (weekly or monthly) and regular (daily use) based on reported frequency in the past three months. Each substance was modeled individually as an outcome in ordinal regression model adjusting for demographic factors of sex, education and country. Stratified analyses were performed to assess country-specific effects.ResultsIndividuals with BD had significantly higher odds of alcohol consumption compared to those with SCZ. Males showed higher odds of alcohol, tobacco, and khat consumption compared to females. Significant variations in alcohol, tobacco, and cannabis consumption were observed across different study countries. Education level was significantly associated with khat consumption, with higher education levels associated with lower odds of consumption.ConclusionCountry and sex-specific differences in substance use behaviors exist in a large-scale African case-control study of people with psychosis. The findings here are in line with previous work regarding sex and regional differences, though they differ from studies conducted in US populations in that minimal evidence was found to support a relationship between level of education and frequency of substance use for any of the substances studied. This suggests that there may be distinct sociodemographic correlates of substance use in Africa and highlights the critical need to consider individuals of diverse ancestry in large-scale studies while also taking into account regional differences when examining substance use behaviors.
Global, Regional, and National Burden of Nontraumatic Subarachnoid Hemorrhage: The Global Burden of Disease Study 2021.
ImportanceNontraumatic subarachnoid hemorrhage (SAH) represents the third most common stroke type with unique etiologies, risk factors, diagnostics, and treatments. Nevertheless, epidemiological studies often cluster SAH with other stroke types leaving its distinct burden estimates obscure.ObjectiveTo estimate the worldwide burden of SAH.Design, setting, and participantsBased on the repeated cross-sectional Global Burden of Disease (GBD) 2021 study, the global burden of SAH in 1990 to 2021 was estimated. Moreover, the SAH burden was compared with other diseases, and its associations with 14 individual risk factors were investigated with available data in the GBD 2021 study. The GBD study included the burden estimates of nontraumatic SAH among all ages in 204 countries and territories between 1990 and 2021.ExposuresSAH and 14 modifiable risk factors.Main outcomes and measuresAbsolute numbers and age-standardized rates with 95% uncertainty intervals (UIs) of SAH incidence, prevalence, mortality, and disability-adjusted life-years (DALYs) as well as risk factor-specific population attributable fractions (PAFs).ResultsIn 2021, the global age-standardized SAH incidence was 8.3 (95% UI, 7.3-9.5), prevalence was 92.2 (95% UI, 84.1-100.6), mortality was 4.2 (95% UI, 3.7-4.8), and DALY rate was 125.2 (95% UI, 110.5-142.6) per 100 000 people. The highest burden estimates were found in Latin America, the Caribbean, Oceania, and high-income Asia Pacific. Although the absolute number of SAH cases increased, especially in regions with a low sociodemographic index, all age-standardized burden rates decreased between 1990 and 2021: the incidence by 28.8% (95% UI, 25.7%-31.6%), prevalence by 16.1% (95% UI, 14.8%-17.7%), mortality by 56.1% (95% UI, 40.7%-64.3%), and DALY rate by 54.6% (95% UI, 42.8%-61.9%). Of 300 diseases, SAH ranked as the 36th most common cause of death and 59th most common cause of DALY in the world. Of all worldwide SAH-related DALYs, 71.6% (95% UI, 63.8%-78.6%) were associated with the 14 modeled risk factors of which high systolic blood pressure (population attributable fraction [PAF] = 51.6%; 95% UI, 38.0%-62.6%) and smoking (PAF = 14.4%; 95% UI, 12.4%-16.5%) had the highest attribution.Conclusions and relevanceAlthough the global age-standardized burden rates of SAH more than halved over the last 3 decades, SAH remained one of the most common cardiovascular and neurological causes of death and disabilities in the world, with increasing absolute case numbers. These findings suggest evidence for the potential health benefits of proactive public health planning and resource allocation toward the prevention of SAH.
A qualitative risk assessment of Crimean-Congo haemorrhagic fever in Nigeria: implications for One Health response.
BackgroundCrimean-Congo Haemorrhagic Fever (CCHF) is a severe tick-borne viral disease. Increasing cases in West Africa suggest potential undetected circulation in Nigeria.MethodsA One Health Joint Risk Assessment was conducted to identify transmission pathways and assess the likelihood and impact of human CCHF infections at the human-animal-environment interface in Nigeria. Risk framing involved developing structured questions for potential Crimean-Congo Haemorrhagic Fever virus (CCHFV) transmission scenarios. A scoping review was conducted and median seroprevalence values were reported. The likelihood, impact and data uncertainty for human infection scenarios were used for a qualitative estimation of risk.ResultsHuman contact with infected livestock during farming, veterinary practices and exposure to ticks was identified as a key infection route. Most cases in Nigeria (66.7%) were identified via serology, with a median human seroprevalence of 6.1% and cattle seroprevalence of 30.2%. CCHFV has been isolated from Rhipicephalus ticks. Four risk assessment questions were defined and focused on veterinarians, abattoir workers, herders, wildlife rangers and healthcare workers. Animal-related professions had a moderate likelihood of infection.ConclusionStrengthening One Health surveillance, vector control and multisector infection prevention is crucial to reducing the risk of CCHF and averting future outbreaks.
Experiences with the Implementation of Cuban Health Cooperation Programs in Low and Middle-Income Countries: A Scoping Review.
BACKGROUND: Health systems in low and middle-income countries (LMICs) face chronic Human Resources for Health (HRH) shortages. This is especially worse in rural and primary healthcare settings. The Cuban government since 1960s has been implementing a policy strategy for producing healthcare workers for export, to boost their economy. Several LMICs have since established health cooperation programs with Cuba to import health workers to address their shortages. This review aimed to examine the emergence, design, utility, outcomes, and lessons learned from the implementation of these programs. METHODS: We conducted a scoping review using the Joanna Briggs Institute (JBI) methodology and searched for literature across four databases. Two independent reviewers screened the articles and selected relevant articles based on pre-defined criteria. We extracted data and synthesized findings using thematic analysis. RESULTS: We included 71 articles after screening 3509 articles. Cuban health cooperation programs have been implemented in many LMICs in South America, Africa, Southeast Asia, and the Pacific region. These programs are formalized primarily through bilateral agreements and implemented as exchange initiatives. This involves importing Cuban healthcare workers and sending collaborating country students to study in Cuba. These programs aimed to address HRH shortages and maldistribution, inadequate training capacity, and respond to medical emergencies in the host countries. Cuban healthcare workers, primarily family physicians, within the host countries; are deployed in primary healthcare settings, increasing the rural health workforce, and improving healthcare access and outcomes. These programs have faced several challenges including opposition from local medical professionals, underutilization due to poorly coordinated recruitment, and language barrier. CONCLUSION: Cuban health cooperations in LMICs have shown diverse results based on their structures. Long-term comprehensive programs have proven to be more successful in boosting the healthcare workforce and enhancing health outcomes. Key factors for optimizing HRH health cooperation include effective collaborative decision-making and need-based deployment.
An adaptive multiarm randomised trial of biomedical and psychosocial interventions to improve convalescence following severe acute malnutrition in sub-Saharan Africa: Co-SAM trial protocol.
INTRODUCTION: Children discharged from hospital following management of complicated severe acute malnutrition (SAM) have a high risk of mortality, readmission and failed nutritional recovery. Current management approaches fail to sufficiently promote convalescence after inpatient nutritional rehabilitation. Novel interventions during the post-discharge period could enhance convalescence to help children survive and thrive. METHODS AND ANALYSIS: The Co-SAM trial is an adaptive, multicountry, phase III, individually randomised clinical trial, based on the principles that (i) interacting biological and social factors drive multimorbidity in children with SAM, and (ii) both medical and psychosocial interventions may therefore ameliorate underlying causal pathways to reduce morbidity and mortality and improve recovery. Children aged 6-59 months with complicated SAM, who have stabilised and started the transition to ready-to-use therapeutic food (RUTF), will be enrolled and randomised to one of five trial arms (standard-of-care alone; antimicrobials; reformulated RUTF; psychosocial support; or a combination of all strategies). Standard-of-care, which is provided in all trial arms, includes RUTF until nutritional recovery (defined as weight-for-height Z-score >-2, mid-upper arm circumference >12.5 cm and oedema-free since the last study visit), and other management recommended in WHO guidelines. The 12-week antimicrobial package provides daily co-formulated rifampicin and isoniazid (with pyridoxine) and 3 days of azithromycin monthly. The reformulated RUTF, which incorporates medium-chain triglycerides and hydrolysed protein to increase nutrient bioavailability and reduce metabolic stress, is provided at the same dose and duration as standard RUTF. The 12-week psychosocial package includes caregiver problem-solving therapy, educational modules, peer support groups and child play. The combined arm includes all interventions. Children start their intervention package prior to hospital discharge, with follow-up data collection in study clinics at 2, 4, 6, 8, 12 and 24 weeks. The primary composite outcome is death, hospitalisation or failed nutritional recovery within 24 weeks post-randomisation. An interim analysis will allow unpromising arms to be dropped, while the final analysis will be conducted when 1266 children have completed the study. Embedded process evaluation and laboratory substudies will explore the mechanisms of action of the interventions. ETHICS AND DISSEMINATION: The trial has been approved by ethics committees in Zimbabwe, Zambia, Kenya and UK. Dissemination will be via community advisory boards in each country; Ministries of Health; and dialogue with policymakers including UNICEF. TRIAL REGISTRATION NUMBER: Clinicaltrials.gov: NCT05994742; Pan African Clinical Trials Registry: PACTR202311478928378.
Molnupiravir or nirmatrelvir-ritonavir plus usual care versus usual care alone in patients admitted to hospital with COVID-19 (RECOVERY): a randomised, controlled, open-label, platform trial.
BackgroundMolnupiravir and nirmatrelvir-ritonavir are oral antivirals that have shown efficacy in preventing disease progression in outpatients with COVID-19. We aimed to evaluate these treatments for patients hospitalised with COVID-19 pneumonia, for whom data on these antivirals are scarce.MethodsThe RECOVERY trial is a randomised, controlled, open-label, adaptive platform trial testing treatments for COVID-19. In this study we report the molnupiravir and nirmatrelvir-ritonavir comparisons from the RECOVERY trial. In each comparison, participants aged 18 years and older were randomly allocated (1:1) to the relevant antiviral (5 days of molnupiravir 800 mg twice daily or 300 mg nirmatrelvir and 100 mg ritonavir twice daily) in addition to usual care, or to usual care alone. The molnupiravir comparison was conducted at 75 hospitals in the UK, two in Nepal, and two in Indonesia; the nirmatrelvir-ritonavir comparison was conducted at 32 hospitals in the UK. Participants could take part in both comparisons. The primary outcome was 28-day mortality, and secondary outcomes were time to discharge alive from hospital and progression to invasive ventilation or death. Analysis was by intention to treat. Both comparisons were stopped because of low recruitment. This study is registered with ISRCTN, 50189673, and ClinicalTrials.gov, NCT04381936.FindingsFrom Jan 24, 2022, to May 24, 2023, 923 participants were recruited to the molnupiravir comparison (445 allocated to molnupiravir and 478 to usual care), and from March 31, 2022, to May 24, 2023, 137 participants were recruited to the nirmatrelvir-ritonavir comparison (68 allocated to nirmatrelvir-ritonavir and 69 to usual care). More than three-quarters of participants were vaccinated and had antispike antibodies at randomisation, and more than two-thirds were receiving other SARS-CoV-2 antivirals. In the molnupiravir comparison, 74 (17%) participants allocated to molnupiravir and 79 (17%) allocated to usual care died within 28 days (hazard ratio [HR] 0·93 [95% CI 0·68-1·28], p=0·66). In the nirmatrelvir-ritonavir comparison, 13 (19%) participants allocated to nirmatrelvir-ritonavir and 13 (19%) allocated to usual care died within 28 days (HR 1·02 [0·47-2·23], p=0·96). In neither comparison was there evidence of any difference in the duration of hospitalisation or the proportion of participants progressing to invasive ventilation or death.InterpretationAdding molnupiravir or nirmatrelvir-ritonavir to usual care was not associated with improvements in clinical outcomes. However, low recruitment meant a clinically meaningful benefit of treatment could not be ruled out, particularly for nirmatrelvir-ritonavir.FundingUK Research and Innovation (UK Medical Research Council), the National Institute for Health and Care Research, and the Wellcome Trust.
Vaccination with mRNA-encoded nanoparticles drives early maturation of HIV bnAb precursors in humans.
A leading HIV vaccine strategy requires a priming immunogen to induce broadly neutralizing antibody (bnAb) precursors, followed by a series of heterologous boosters to elicit somatic hypermutation (SHM) and produce bnAbs. In two randomized, open-label phase 1 human clinical trials, IAVI-G002 in the United States and IAVI-G003 in Rwanda and South Africa, we evaluated the safety and immunogenicity of mRNA-encoded nanoparticles as priming immunogens (both trials) and first-boosting immunogens (IAVI-G002). The vaccines were generally safe and well tolerated, except 18% of IAVI-G002 participants experienced skin reactions. Priming induced bnAb precursors with substantial frequencies and SHM, and heterologous boosting elicited increased SHM, affinity, and neutralization activity toward bnAb development. The results establish clinical proof of concept that heterologous boosting can advance bnAb-precursor maturation and demonstrate bnAb priming in Africa where the HIV burden is highest.
Detection of mpox and other orthopoxviruses using a lateral flow device as a point-of-care diagnostic.
In 2022, the World Health Organization declared the worldwide outbreak of mpox to be a public health emergency of international concern. The causative monkeypox virus (MPXV) belonged to clade IIb and is transmitted through sexual contact with a low case fatality rate (0.1%), which, together with under-detection, all contributed to a rapid global spread particularly within the MSM (men who have sex with men) community. As MPXV clade II remains circulating worldwide, a new outbreak of the more fatal clade I disease has been declared in Central and East Africa, and remains uncontrolled in part due to the lack of point-of-care (POC) diagnostics for rapid decisions on treatment and self-isolation. To address the lack of POC solutions for mpox, we have designed and evaluated an orthopoxvirus-specific lateral flow device (LFD) that could be used for the diagnosis of mpox. Using an LFD comprising four monoclonal antibodies against the A27 protein, we demonstrate sensitivity to 3 × 105 pfu/mL. This sensitivity is expected to be sufficient for the detection of MPXV from lesion sites and may also be sufficient for other sample types such as saliva and urine. We found that the presence of guanidinium thiocyanate, a common ingredient in inactivating viral transport media, masked the LFD antigen, resulting in false negatives. POC diagnosis of mpox may be possible using an LFD to reduce delays arising from sample shipment to centralized laboratory testing facilities. In order to achieve this, our work demonstrates that an LFD-optimized buffer is required, as the sample collection buffer may have a detrimental impact on sensitivity for clinical material.IMPORTANCEMpox cases have dramatically increased both in traditionally monkeypox virus endemic countries and also worldwide. This increase comes at a time when immunity derived from smallpox vaccination is no longer available. Diagnosis of mpox is complicated due to both disease presentation and the availability of local diagnostic laboratories. The availability of a point-of-care diagnostic tool such as an lateral flow device (LFD) would play an important role to both diagnose and prevent onward transmission. This manuscript provides developers and assessors with key data for defining true sensitivity and specificity of a successful LFD in addition to buffer conditions for sample collection.
Genetic surveillance of Plasmodium falciparum populations following treatment policy revisions in the Greater Mekong Subregion.
Genetic surveillance of Plasmodium falciparum (Pf) can track antimalarial-resistant strains, to inform decision-making by National Malaria Control Programmes (NMCPs). The GenRe-Mekong project prospectively collected 5982 samples in the Greater Mekong Subregion (GMS) between 2017 and 2022, genotyping drug resistance markers, and barcodes that recapitulate genetic variation. Genotypes were analyzed with the grcMalaria R package, first described in this paper, to translate genetic epidemiology data into actionable visual information. Since 2020, Pf incidences decreased rapidly, accompanied by a decline of dihydroartemisinin-piperaquine (DHA-PPQ) resistant lineages, previously dominant in the eastern GMS. The frequency of plasmepsin2/3 amplifications, conferring piperaquine resistance, dropped from 62% in 2017-2019 to 2% in 2022, coinciding with a switch in frontline therapy in Cambodia, Thailand, and Vietnam. While regional artemisinin resistance levels remained high, no evidence of emerging mefloquine resistance was found. Routine genetic surveillance proved valuable in monitoring rapid parasite population changes in response to public health interventions, providing actionable information for NMCPs.
Genomics reveals zoonotic and sustained human Mpox spread in West Africa.
Five years before the 2022 multi-country mpox outbreak, Nigeria and Cameroon reported their first cases in over three decades.1,2 While Nigeria's outbreak is recognized as an ongoing human epidemic, the drivers of Cameroon's resurgence remain unclear.3,4 The rate of zoonoses remains uncertain in both countries, and gaps in genomic data obscure the timing, zoonotic and geographic origin of mpox virus (MPXV) emergence in humans. To address these uncertainties, we generated 118 MPXV genomes from Nigeria and Cameroon from 2018-2023. Our findings show that, in contrast to Nigeria, cases in Cameroon are the result of repeated zoonoses, with two distinct zoonotic lineages circulating across the Nigeria-Cameroon border. Our findings suggest that shared animal populations in the cross-border forest ecosystems drive virus emergence and spread. Accordingly, we identify the closest zoonotic outgroup to the Nigerian human epidemic lineage (hMPXV-1) in a southern Nigerian border state. We estimate that the shared ancestor of the zoonotic outgroup and hMPXV-1 circulated in animals in southern Nigeria in late 2013. We estimate that hMPXV-1 emerged in humans in August 2014 in the southern Rivers State and circulated undetected for three years. Rivers State acted as the main source of viral spread across the human epidemic. Our study sheds light on MPXV's recent establishment in the human population and highlights the risk of persistent zoonotic emergence of MPXV in the complex border regions of Cameroon and Nigeria.
Fatal Mycobacterium avium meningitis in an HIV-negative Vietnamese man: a case report
Background: Nontuberculous mycobacteria are environmental mycobacteria that rarely cause human disease, especially in the central nervous system. Central nervous system infection by Mycobacterium avium complex, the most common pathogen among nontuberculous mycobacteria species, is rare and seldom reported, even in those with advanced human immunodeficiency virus infection. We describe a case of Mycobacterium avium complex meningitis with cerebral hemorrhage in an human immunodeficiency virus uninfected man in Vietnam. Case presentation: A 56-year-old Vietnamese man with hypertension was hospitalized with a 5-day history of headache, dizziness, low-grade fever, and unresponsive to 5 days of oral antibiotics. A brain magnetic resonance imaging, performed on day 12, showed hydrocephalus and lacunar infarct. The patient did not improve with 8 days of empirical treatment with ceftriaxone, vancomycin, dexamethasone, and meropenem, and was transferred to a referral hospital for tropical diseases. At the second hospital admission, a cerebrospinal fluid analysis showed a white cell count of 22,518 cells/μL with 81% neutrophils, protein 1.72 g/L, and glucose 0.85 mmol/L. Acid-fast bacilli smear of the cerebrospinal fluid was positive. Molecular testing of the cerebrospinal fluid was negative on GeneXpert Ultra testing, while the line probe assay was positive for Mycobacterium avium. Blood cultures at two sites, cerebrospinal fluid cultures for bacteria and fungi, and human immunodeficiency virus Ag/Ab test were negative. The patient was continuously administered meropenem with the addition of azithromycin, rifampin, and ethambutol. Then, 1 day after nontuberculous mycobacteria treatment, he developed right-sided hemiplegia, and brain computed tomography showed a hemorrhage in the parietal area, adjacent to the left lateral ventricle, and left lateral intraventricular hemorrhage shifts the midline to the right. He was transferred to the third referral general hospital and died 22 days after the onset of symptoms. Conclusion: Nontuberculous mycobacteria-central nervous system infection might mimic unresponsive pyogenic bacterial meningitis. A rapid and accurate diagnosis is essential for initiating appropriate therapy for this deadly disease.
Digital Health Policy and Programs for Hospital Care in Vietnam: Scoping Review
Background There are a host of emergent technologies with the potential to improve hospital care in low- and middle-income countries such as Vietnam. Wearable monitors and artificial intelligence–based decision support systems could be integrated with hospital-based digital health systems such as electronic health records (EHRs) to provide higher level care at a relatively low cost. However, the appropriate and sustainable application of these innovations in low- and middle-income countries requires an understanding of the local government’s requirements and regulations such as technology specifications, cybersecurity, data-sharing protocols, and interoperability. Objective This scoping review aims to explore the current state of digital health research and the policies that govern the adoption of digital health systems in Vietnamese hospitals. Methods We conducted a scoping review using a modification of the PRISMA-ScR (Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews) guidelines. PubMed and Web of Science were searched for academic publications, and Thư Viện Pháp Luật, a proprietary database of Vietnamese government documents, and the Vietnam Electronic Health Administration website were searched for government documents. Google Scholar and Google Search were used for snowballing searches. The sources were assessed against predefined eligibility criteria through title, abstract, and full-text screening. Relevant information from the included sources was charted and summarized. The review process was primarily undertaken by one researcher and reviewed by another researcher during each step. Results In total, 11 academic publications and 20 government documents were included in this review. Among the academic studies, 5 reported engineering solutions for information systems in hospitals, 2 assessed readiness for EHR implementation, 1 tested physicians’ performance before and after using clinical decision support software, 1 reported a national laboratory information management system, and 2 reviewed the health system’s capability to implement eHealth and artificial intelligence. Of the 20 government documents, 19 were promulgated from 2013 to 2020. These regulations and guidance cover a wide range of digital health domains, including hospital information management systems, general and interoperability standards, cybersecurity in health organizations, conditions for the provision of health information technology (HIT), electronic health insurance claims, laboratory information systems, HIT maturity, digital health strategies, electronic medical records, EHRs, and eHealth architectural frameworks. Conclusions Research about hospital-based digital health systems in Vietnam is very limited, particularly implementation studies. Government regulations and guidance for HIT in health care organizations have been released with increasing frequency since 2013, targeting a variety of information systems such as electronic medical records, EHRs, and laboratory information systems. In general, these policies were focused on the basic specifications and standards that digital health systems need to meet. More research is needed in the future to guide the implementation of digital health care systems in the Vietnam hospital setting.
Kinetics of Neutralizing Antibodies against Omicron Variant in Vietnamese Healthcare Workers after Primary Immunization with ChAdOx1-S and Booster Immunization with BNT162b2
ABSTRACT. We studied the development and persistence of neutralizing antibodies against SARS-CoV-2 ancestral strain, and Delta and Omicron (BA.1 and BA.2) variants in Vietnamese healthcare workers (HCWs) up to 15 weeks after booster vaccination. We included 47 HCWs, including group 1 (G1, N = 21) and group 2 (G2; N = 26) without and with breakthrough Delta variant infection before booster immunization, respectively). The study participants had completed primary immunization with ChAdOx1-S and booster vaccination with BNT162b2. Neutralizing antibodies were measured using a surrogate virus neutralization assay. Of the 21 study participants in G1, neutralizing antibodies against ancestral strain, Delta variant, BA.1, and BA.2 were (almost) abolished at month 8 after the second dose, but all had detectable neutralizing antibodies to the study viruses at week 2 post booster dose. Of the 26 study participants in G2, neutralizing antibody levels to BA.1 and BA.2 were significantly higher than those to the corresponding viruses measured at week 2 post breakthrough infection and before the booster dose. At week 15 post booster vaccination, neutralizing antibodies to BA.1 and BA.2 dropped significantly, with more profound changes observed in those without breakthrough Delta variant infection. Booster vaccination enhanced neutralizing activities against ancestral strain and Delta variant compared with those induced by primary vaccination. These responses were maintained at high levels for at least 15 weeks. Our findings emphasize the importance of the first booster dose in producing cross-neutralizing antibodies against Omicron variant. A second booster to maintain long-term vaccine effectiveness against the currently circulating variants merits further research.