Modeling the potential public health impact of different vaccination strategies with an adapted vaccine in South Africa.

BACKGROUND: COVID-19 vaccines adapted to newly emerging circulating variants are necessary to better protect the population due to the evolving nature of the SARS-CoV-2 virus. RESEARCH DESIGN AND METHODS: The South African population was stratified by age and risk (defined by comorbidities such as diabetes, obesity, smoking, cancer, and asthma), and HIV status. The outcomes of different vaccination strategies based on age, risk, and HIV status were estimated using a Markov-decision tree model based on age-specific inputs derived from the literature and South African surveillance data. RESULTS: Vaccinating older adults and those with comorbidities was estimated to avert 111,179 infections 18,281 hospitalizations, and 3,868 deaths, resulting in savings of ZAR 1,260 million (USD 67 million) and ZAR 3,205 million (USD 170 million) in direct and indirect costs, respectively. Similar results were obtained when considering strategies targeting older adults and the HIV population. Expanding vaccination to 75% of the standard-risk population prevented more infections (401%), hospitalizations (167%), and deaths (67%) and increased the direct (232%) and indirect (455%) cost savings compared to the base case. CONCLUSIONS: Implementing widespread vaccination strategies that utilize a vaccine adapted to the prevailing circulating variant in South Africa would result in significant public health and economic gains.

Progression of pain in ambulatory HIV-positive South Africans.

Cross-sectional studies report that pain in ambulatory HIV-infected individuals is frequent and often undermanaged. Expanding access to HIV treatment in developing countries means that infected individuals are living longer, but there is a dearth of pain-directed studies from developing countries that describe the progression of pain and its treatment over any period of time. The aim of this study was to characterize the progression of pain and its treatment over a 6-month period in 92 ambulatory HIV-positive patients attending an outpatient clinic in Johannesburg, South Africa. We used the Wisconsin Brief Pain Questionnaire to assess changes in pain intensity, pain sites, pain interference, and pain treatment. At visit 1, pain was present in 78 of 92 patients (85%). Of the 78 patients with pain, 67 had moderate or severe pain (86%) and pain affected two or more body sites simultaneously in 57 of these patients (73%). After 6 months, pain prevalence still was high, but had fallen to 50 patients (54%). Of the patients with pain at visit 2, the proportion with moderate or severe pain (82%), or two or more pain sites (62%) had decreased. Analgesic use was low at both time points (5% and 25% analgesic use at visit 1 and 2, respectively). Despite the high pain burden, pain interference in daily activities was very low across the period assessed. The burden of pain in this cohort of ambulatory HIV-positive patients was high, but there were significant reductions in pain burden over time.

Validation of the Wisconsin Brief Pain Questionnaire in a multilingual South African population.

Assessment of pain intensity and its effect on quality of life is important for proper management of pain, but no validated pain assessment tools that assess pain intensity and the interference pain has on daily life are available in indigenous South African languages. Therefore, the aim of this study was to validate translated versions of the Wisconsin Brief Pain Questionnaire (WBPQ) in South African HIV-positive patients. The WBPQ was translated into three indigenous South African languages, Setswana, isiZulu, and Xitsonga. We interviewed 452 ambulatory HIV-positive patients (327 urban and 125 rural patients) between the ages of 20 and 76 years old. Factor analysis to assess construct validity identified a two-factor structure (pain intensity and pain interference) for the isiZulu (n=132), Xitsonga (n=125), and Setswana (n=66) versions of the WBPQ, whereas a three-factor structure (pain intensity, mood interference, and activity interference) was identified for the English (completed by English second-language speakers, n=129) version of the WBPQ. Cronbach alphas, calculated to assess the reliability of the pain intensity and pain interference scales, were greater than 0.70 for all scales in all four versions of the WBPQ, showing internal consistency within the dimensions. These results provide evidence of validity for an easily administered questionnaire, which assesses pain intensity and pain interference, in three indigenous South African languages, and for English second-language speakers, in a population of South African HIV-positive patients.

Body temperature, behavior, and plasma cortisol changes induced by chronic infusion of Staphylococcus aureus in goats.

Most experimentally induced fevers are acute, usually lasting approximately 6-12 h, and thus do not mimic chronic natural fevers, which can extend over several days or more. To produce a model of chronic natural fever, we infused eight goats (Capra hircus) intravenously with 2 ml of 2 x 10(11) cell walls of Staphylococcus aureus (S. aureus) for 6 days using osmotic infusion pumps (10 microl/h) while measuring changes in body temperature, behavior, and plasma cortisol concentration. Seven control animals were infused with sterile saline. Abdominal temperature-sensitive data loggers and osmotic infusion pumps were implanted under halothane anesthesia. To compare our new model with existing models of experimental fever, we also administered 2-ml bolus intravenous injections of 2 x 10(11) S. aureus cell walls, 0.1 microg/kg lipopolysaccharide (Escherichia coli, serotype 0111:B4), and sterile saline in random order to six other goats. Bolus injection of lipopolysaccharide and S. aureus induced typical acute phase responses, characterized by fevers lasting approximately 6 h, sickness behavior, and increased plasma cortisol concentration. Infusion of S. aureus evoked prolonged fevers, which lasted for approximately 3 days, starting on day 4 of infusion (ANOVA, P < 0.05), and did not disrupt the normal circadian rhythm of body temperature. However, pyrogen infusion did not cause plasma cortisol concentration to rise (ANOVA, P > 0.05) or the expression of sickness behavior. In conclusion, infusion of S. aureus produced a fever response resembling that of sustained natural fevers but did not elicit the cortisol and behavioral responses that often are described clinically and during short-term experimental fevers.