Evaluating Scope and Bias of Population-Level Measles Serosurveys: A Systematized Review and Bias Assessment.

BACKGROUND: Measles seroprevalence data have potential to be a useful tool for understanding transmission dynamics and for decision making efforts to strengthen immunization programs. In this study, we conducted a systematized review and bias assessment of all primary data on measles seroprevalence in low- and middle-income countries (as defined by World Bank 2021 income classifications) published from 1962 to 2021. METHODS: On 9 March 2022, we searched PubMed for all available data. We included studies containing primary data on measles seroprevalence and excluded studies if they were clinical trials or brief reports, from only health-care workers, suspected measles cases, or only vaccinated persons. We extracted all available information on measles seroprevalence, study design, and seroassay protocol. We conducted a bias assessment based on multiple categories and classified each study as having low, moderate, severe, or critical bias. This review was registered with PROSPERO (CRD42022326075). RESULTS: We identified 221 relevant studies across all World Health Organization regions, decades, and unique age ranges. The overall crude mean seroprevalence across all studies was 78.0% (SD: 19.3%), and the median seroprevalence was 84.0% (IQR: 72.8-91.7%). We classified 80 (36.2%) studies as having severe or critical overall bias. Studies from country-years with lower measles vaccine coverage or higher measles incidence had higher overall bias. CONCLUSIONS: While many studies have substantial underlying bias, many studies still provide some insights or data that could be used to inform modelling efforts to examine measles dynamics and programmatic decisions to reduce measles susceptibility.

A qualitative study on the willingness and influencing factors of master of geriatric nursing specialist postgraduates to volunteer for home respite care for disabled elderly families.

BACKGROUND: As China's population ages, the demand for care for the disabled elderly is increasing, and family caregivers find it challenging to meet the comprehensive care needs of the disabled elderly. Through home respite services, families of the disabled elderly can receive help and support from specialized nursing professionals to ease the burden on family caregivers and provide high-quality services. This study explores the willingness and influencing factors of Master of Geriatric Nursing Specialist postgraduates in China to volunteer to provide home respite services for disabled elderly individuals. METHODS: A qualitative study based on Grounded Theory used Strauss and Corbin's programmatic version. A purposive sampling method was employed to conduct semi-structured interviews with 12 Master of Geriatric Nursing Specialist postgraduates from a tertiary hospital in Changsha, Hunan Province, China. RESULTS: The willingness of Master of Geriatric Nursing Specialist postgraduates to volunteer to provide home respite services for the disabled elderly was established as a core category, which was influenced by three main categories: personal factors, service object factors, and social factors, and nine categories formed from 39 initial concepts were included under the main category. CONCLUSIONS: Influenced by China's traditional cultural background, Master of Geriatric Nursing Specialist postgraduates in China have shown high motivation in volunteering to provide home respite services for the families of the disabled elderly but have been challenged by several challenges from China's healthcare environment and education system. Relevant departments need to adopt a series of policies and measures to increase volunteers' willingness to participate in respite care and promote its development.

Impact and cost-effectiveness of measles vaccination through microarray patches in 70 low-income and middle-income countries: mathematical modelling and early-stage economic evaluation.

BACKGROUND: Microarray patches (MAPs) are a promising technology being developed to reduce barriers to vaccine delivery based on needles and syringes (N&S). To address the evidence gap on the public health value of applying this potential technology to immunisation programmes, we evaluated the health impact on measles burden and cost-effectiveness of introducing measles-rubella MAPs (MR-MAPs) in 70 low-income and middle-income countries (LMICs). METHODS: We used an age-structured dynamic model of measles transmission and vaccination to project measles cases, deaths and disability-adjusted life-years during 2030-2040. Compared with the baseline scenarios with continuing current N&S-based practice, we evaluated the introduction of MR-MAPs under different measles vaccine coverage projections and MR-MAP introduction strategies. Costs were calculated based on the ingredients approach, including direct cost of measles treatment, vaccine procurement and vaccine delivery. Model-based burden and cost estimates were derived for individual countries and country income groups. We compared the incremental cost-effectiveness ratios of introducing MR-MAPs to health opportunity costs. RESULTS: MR-MAP introduction could prevent 27%-37% of measles burden between 2030 and 2040 in 70 LMICs, compared with the N&S-only immunisation strategy. The largest health impact could be achieved under lower coverage projection and accelerated introduction strategy, with 39 million measles cases averted. Measles treatment cost is a key driver of the net cost of introduction. In countries with a relatively higher income, introducing MR-MAPs could be a cost-saving intervention due to reduced treatment costs. Compared with country-specific health opportunity costs, introducing MR-MAPs would be cost-effective in 16%-81% of LMICs, depending on the MR-MAPs procurement prices and vaccine coverage projections. CONCLUSIONS: Introducing MR-MAPs in LMICs can be a cost-effective strategy to revitalise measles immunisation programmes with stagnant uptake and reach undervaccinated children. Sustainable introduction and uptake of MR-MAPs has the potential to improve vaccine equity within and between countries and accelerate progress towards measles elimination.

Modelling the global burden of drug-resistant tuberculosis avertable by a post-exposure vaccine.

There have been notable advances in the development of vaccines against active tuberculosis (TB) disease for adults and adolescents. Using mathematical models, we seek to estimate the potential impact of a post-exposure TB vaccine, having 50% efficacy in reducing active disease, on global rifampicin-resistant (RR-) TB burden. In 30 countries that together accounted for 90% of global RR-TB incidence in 2018, a future TB vaccine could avert 10% (95% credible interval: 9.7-11%) of RR-TB cases and 7.3% (6.6-8.1%) of deaths over 2020-2035, with India, China, Indonesia, Pakistan, and the Russian Federation having the greatest contribution. This impact would increase to 14% (12-16%) and 31% (29-33%) respectively, when combined with improvements in RR-TB diagnosis and treatment relative to a scenario of no vaccine and no such improvements. A future TB vaccine could have important implications for the global control of RR-TB, especially if implemented alongside enhancements in management of drug resistance.

Potential impact of the COVID-19 pandemic on HIV, tuberculosis, and malaria in low-income and middle-income countries: a modelling study.

BACKGROUND: COVID-19 has the potential to cause substantial disruptions to health services, due to cases overburdening the health system or response measures limiting usual programmatic activities. We aimed to quantify the extent to which disruptions to services for HIV, tuberculosis, and malaria in low-income and middle-income countries with high burdens of these diseases could lead to additional loss of life over the next 5 years. METHODS: Assuming a basic reproduction number of 3·0, we constructed four scenarios for possible responses to the COVID-19 pandemic: no action, mitigation for 6 months, suppression for 2 months, or suppression for 1 year. We used established transmission models of HIV, tuberculosis, and malaria to estimate the additional impact on health that could be caused in selected settings, either due to COVID-19 interventions limiting activities, or due to the high demand on the health system due to the COVID-19 pandemic. FINDINGS: In high-burden settings, deaths due to HIV, tuberculosis, and malaria over 5 years could increase by up to 10%, 20%, and 36%, respectively, compared with if there was no COVID-19 pandemic. The greatest impact on HIV was estimated to be from interruption to antiretroviral therapy, which could occur during a period of high health system demand. For tuberculosis, the greatest impact would be from reductions in timely diagnosis and treatment of new cases, which could result from any prolonged period of COVID-19 suppression interventions. The greatest impact on malaria burden could be as a result of interruption of planned net campaigns. These disruptions could lead to a loss of life-years over 5 years that is of the same order of magnitude as the direct impact from COVID-19 in places with a high burden of malaria and large HIV and tuberculosis epidemics. INTERPRETATION: Maintaining the most critical prevention activities and health-care services for HIV, tuberculosis, and malaria could substantially reduce the overall impact of the COVID-19 pandemic. FUNDING: Bill & Melinda Gates Foundation, Wellcome Trust, UK Department for International Development, and Medical Research Council.

Explaining age disparities in tuberculosis burden in Taiwan: a modelling study.

BACKGROUND: Tuberculosis (TB) burden shows wide disparities across ages in Taiwan. In 2016, the age-specific notification rate in those older than 65 years old was about 100 times as much as in those younger than 15 years old (185.0 vs 1.6 per 100,000 population). Similar patterns are observed in other intermediate TB burden settings. However, driving mechanisms for such age disparities are not clear and may have importance for TB control efforts. METHODS: We hypothesised three mechanisms for the age disparity in TB burden: (i) older age groups bear a higher risk of TB progression due to immune senescence, (ii) elderly cases acquired TB infection during a past period of high transmission, which has since rapidly declined and thus contributes to little recent infections, and (iii) assortative mixing by age allows elders to maintain a higher risk of TB infection, while limiting spillover transmission to younger age groups. We developed a series of dynamic compartmental models to incorporate these mechanisms, individually and in combination. The models were calibrated to the TB notification rates in Taiwan over 1997-2016 and evaluated by goodness-of-fit to the age disparities and the temporal trend in the TB burden, as well as the deviance information criterion (DIC). According to the model performance, we compared contributions of the hypothesised mechanisms. RESULTS: The 'full' model including all the three hypothesised mechanisms best captured the age disparities and temporal trend of the TB notification rates. However, dropping individual mechanisms from the full model in turn, we found that excluding the mechanism of assortative mixing yielded the least change in goodness-of-fit. In terms of their influence on the TB dynamics, the major contribution of the 'immune senescence' and 'assortative mixing' mechanisms was to create disparate burden among age groups, while the 'declining transmission' mechanism served to capture the temporal trend of notification rates. CONCLUSIONS: In settings such as Taiwan, the current TB burden in the elderly may be impacted more by prevention of active disease following latent infection, than by case-finding for blocking transmission. Further studies on these mechanisms are needed to disentangle their impacts on the TB epidemic and develop corresponding control strategies.

Modelling the effect of discontinuing universal Bacillus Calmette-Guérin vaccination in an intermediate tuberculosis burden setting.

BACKGROUND: Bacillus Calmette-Guérin (BCG) vaccination is a widely-used public health intervention for tuberculosis (TB) control. In Taiwan, like other intermediate TB burden settings, steadily declining TB incidence raises important questions on whether universal BCG vaccination should be discontinued. Recent surveys on adverse events following immunisation, such as BCG-induced osteomyelitis/osteitis, also suggest a need to re-evaluate the vaccination programme. METHODS: We developed an age-structured transmission dynamic model, calibrated to population demography and age-specific TB notification rates in Taiwan. We adopted 'weak-protection' and 'strong-protection' scenarios, representing a range of characteristics including the duration of BCG protection and vaccine efficacies against TB infection and progression. We estimated averted disability-adjusted life years (DALYs) and incremental costs over 10 years after discontinuing universal BCG vaccination in 2018, 2035, and 2050. We also examined the potential impact of 'surveillance-guided' discontinuation, triggered once notification rates fall to a given threshold. RESULTS: In the weak-protection scenario, discontinuing BCG would result in 2.8 (95% uncertainty range: 2.3, 3.1) additional notified TB cases and -4.1 (-7.7, 0.8) net averted DALYs over 2018-2027. In the strong-protection scenario, 82.9 (72.6, 91.6) additional cases and -402.7 (-506.6, -301.2) averted DALYs would be reported, suggesting a robustly negative health impact. However, in this vaccine scenario, there could be an overall health benefit if BCG is discontinued once TB notification falls below 5 per 100,000 population. The most influential vaccine characteristic for the net health impact is the vaccine efficacy against progression to pulmonary TB. In financial terms, the eliminated cost of the vaccination programme substantially outweighed the incremental cost for TB treatment regardless of BCG protection. CONCLUSIONS: BCG discontinuation may be warranted in intermediate burden settings, depending on the quality of vaccine protection, and the potential for refocusing on other TB control activities for earlier detection and treatment.