COVID-19 herd immunity v. learning to live with the virus

Mutations of SARS-CoV-2 have been associated with increased transmissibility and occasionally reduced sensitivity to neutralising antibody activity induced by past ancestry virus infection or current COVID-19 vaccines. Nevertheless, COVID-19 vaccines have consistently demonstrated high efficacy and effectiveness against COVID-19 severe disease, hospitalisation and death, including disease caused by designated variants of concern. In contrast, COVID-19 vaccines are more heterogeneous in reducing the risk of infection and mild COVID- 19, and are modestly effective in interrupting virus transmission. Ongoing mutations of SARS-CoV-2 resulting in increased transmissibility and relative evasion of neutralising antibody activity induced by past virus infection or COVID-19 vaccines are likely. The duration of protection induced by COVID-19 vaccines is modelled to be relatively short in protecting against infection and mild COVID-19, but is likely to be 2 - 3 years against severe disease. Current experience from the UK and Israel demonstrates that even with high levels of COVID- 19 vaccine coverage (>85% of the adult population), resurgences with new variants of concern remain a strong probability. Nevertheless, such resurgences are not mirrored by high rates of hospitalisation and death compared with what was experienced in relatively COVID-19 vaccine-naive populations. Even though COVID-19 vaccines are unlikely to result in a herd immunity state, their ability to protect against severe COVID-19 and death could allow for a return to normalcy once a large enough proportion of the adult population in a country has been vaccinated

Some Subclasses of Univalent and Bi-Univalent Functions Related to K-Fibonacci Numbers and Modified Sigmoid Function

يهتم هذا البحث بفئات فرعية معينة من الدوال احادية التكافؤ وثنائية التكافؤ فيما يتعلق بمنحنيات تشبه الصدفة المرتبطة بأرقام فيبوناتشي k تتضمن دالة التنشيط السيني المعدلة θ(t)=2/(1+e^(-t) ) ,t ≥0في قرص الوحدة|z|<1. تقديرات المعاملات الاولية |c_2 | , |c_3 | تم التحقق من عدم المساواة Fekete-Szego ̈ ومحدد هانكل الثاني للدوال في فئاتنا.              This paper is interested in certain  subclasses of univalent and bi-univalent functions concerning  to shell- like curves connected with k-Fibonacci numbers involving modified Sigmoid activation function θ(t)=2/(1+e^(-t) ) ,t ≥0 in unit disk |z|<1 . For estimating of the initial coefficients |c_2 | , |c_3 |, Fekete-Szego ̈ inequality and the  second Hankel determinant have been investigated for the functions in our classes.

Maternal and neonatal vitamin D status at birth in black South Africans

Background. Vitamin D deficiency (VDD) in pregnant women has been associated with adverse pregnancy and neonatal outcomes. 25-hydroxyvitamin D (25(OH)D) levels are affected by numerous factors, including vitamin D intake, skin pigmentation, latitude and season of the year; they therefore vary by race and country. Vitamin D status in pregnant women and their offspring in South Africa (SA) is not well established.Objectives. To assess vitamin D status by measuring serum 25(OH)D in pregnant black SA women and their offspring in Johannesburg (latitude 26°S) and to assess whether vitamin D status is affected by maternal HIV infection.Methods. We prospectively enrolled pregnant women and their healthy neonates, and measured 25(OH)D in maternal and cord blood at delivery. Pregnant women were stratified by their HIV status. Predictors of maternal and neonatal VDD (levels <30 nmol/L) were assessed using multiple logistic regression analysis.Results. A total of 291 pregnant women and their healthy neonates were enrolled over a 21-month period. Mean (standard deviation) maternal and cord blood 25(OH)D levels were 57.0 (29.7) and 41.9 (21.0) nmol/L and the prevalence of VDD was 15.9% and 32.8%, respectively. On average, concentrations of 25(OH)D in cord blood were ~80% of those in the mother. There was no association between cord 25(OH)D and gestational age, but levels were associated with birth weight (p<0.001). There were no differences in maternal or cord blood 25(OH)D levels between those HIV-infected or uninfected. The predictor of VDD in mothers was giving birth in winter (odds ratio (OR) 2.87, 95% confidence interval (CI) 1.47 - 5.61), and in neonates the predictors were maternal age (OR 16.5, 95% CI 1.82 - 149), being born in winter (OR 3.68, 95% CI 2.05 - 6.61), being born by caesarean section (OR 4.92, 95% CI 1.56 - 15.57) and being of low birth weight (OR 1.99, 95% CI 1.13 - 3.50).Conclusions. Among black SA women delivering in Johannesburg, about one in six mothers and one in three neonates have 25(OH)D levels indicative of VDD. Maternal HIV status appears not to affect levels of 25(OH)D in either the mother or her neonate. Research on the effects of VDD on the outcomes of pregnancy and the best methods to combat the high prevalence of VDD in women of childbearing age in the SA context is required

One-year post-primary antibody persistence and booster immune response to a DTaP-IPV//PRP~T vaccine (Pentaxim) given at 18 - 19 months of age in South African children primed at 6, 10 and 14 weeks of age with the same vaccine

Objective. To assess the immunogenicity and safety of a pentavalent diphtheria, tetanus, acellular pertussis, inactivated poliovirus, Hib polysaccharide-conjugate vaccine booster.Design, setting and participants. A DTaP-IPV//PRP~T vaccine (Pentaxim, a Sanofi Pasteur AcXim family vaccine) was given to 182 healthy children in South Africa at 18 - 19 months of age following priming with the same vaccine plus a monovalent hepatitis B vaccine at 6, 10 and 14 weeks of  age.Outcome measures. Seroprotection (SP) and seroconversion (SC) rates, geometric mean titres (GMTs) and concentrations (GMCs) were assessed before, and 1 month after, the booster dose. Safety was assessed using parental reports.Results. One month after primary vaccination, at least 94.3% of participants were seroprotected against tetanus (≥0.01 IU/ml), diphtheria (≥0.01 IU/ml), poliovirus (≥8 1/dil) and Haemophilus influenzae type b  (Hib) infection (≥0.15 μg/ml). Before the booster dose, the SP rates  ranged from 65.7% to 100%. One month after the booster dose, SP rates were 97.7% for Hib (anti-PRP titre ≥1.0 μg/ml), 100.0% for diphtheria (≥0.1 IU/ml) and 100% for tetanus (≥0.1 IU/ml) and poliovirus types 1, 2, 3 (≥8 1/dil). At least 95.7% of participants had fourfold post-booster increases in anti-pertussis antibody titres. GMTs increased from 11.21 to 465.51 EU/ml and from 12.89 to 520.35 EU/ml for anti-PT and anti-FHA respectively. Anti-PRP GMT increased from 0.35 to 47.01 μg/ml. The  DTaPIPV// PRP~T vaccine booster was well tolerated, with fever ≥39.0°C in only 1.7% of participants.Conclusions. Antibody persistence following priming was satisfactory. The pentavalent DTaP-IPV//PRP~T vaccine booster was highly immunogenic and well tolerated.S Afr Med J 2011;101:879-883

Immunogenicity and safety of an acellular pertussis, diphtheria, tetanus, inactivated poliovirus, Hib-conjugate combined vaccine (Pentaxim™) and monovalent hepatitis B vaccine at 6, 10 and 14 weeks of age in infants in South Africa

Objective. To assess the immunogenicity and safety data for a pentavalent combination vaccine containing acellular pertussis, inactivated poliovirus, and Haemophilus influenzae (Hib) polysaccharide-conjugate antigens. Methods. A DTaP-IPV//PRP~T vaccine (Pentaxim™) was given at 6, 10 and 14 weeks of age to 212 infants in South Africa. Monovalent hepatitis B vaccine was given concomitantly. Immunogenicity was assessed using seroprotection and seroconversion rates; safety was assessed by monitoring for solicited injection site and systemic adverse events, and follow-up monitoring for unsolicited adverse events and serious adverse events. Results. Immunogenicity was high for each vaccine antigen, and similar to a reference study done in France using a similar (2, 3 and 4 months of age) administration schedule. After the third dose, 94.6% of participants had anti-PRP ≥0.15 μg/ml. The anti-PRP geometric mean antibody titre (GMT) was 2.0 μg/ml. The seroprotection rates for diphtheria and tetanus (≥0.01 IU/ml), poliovirus types 1, 2 and 3 (≥8 1/dil U) and hepatitis B were all 100%. Anti-polio GMTs were very high, 1 453, 1 699 and 2 398 (1/dil U) for types 1, 2 and 3, respectively. The seroconversion/vaccine response rates to pertussis antigens (4-fold increase in antibody concentration) were 97.5% for PT and 83.9% for FHA. Conclusions. The DTaP-IPV//PRP~T vaccine was highly immunogenic at 6, 10 and 14 weeks of age in infants in South Africa, was compatible with the monovalent hepatitis B vaccine, and was well tolerated

An evaluation of the quality of discharge summaries from the general paediatric wards at Chris Hani Baragwanath Academic Hospital, Johannesburg, South Africa

Background. Hospital discharge summaries are deemed to be an essential part of the medical record in South Africa, but formal assessment of their quality is rarely undertaken. At Chris Hani Baragwanath Academic Hospital (CHBAH) in Johannesburg, medical admission notes (bedletters) are difficult to retrieve from the hospital archives and the discharge summary is often the only readily available medical record that documents details of the hospital admission.Objectives. To determine the proportion of discharge summaries that were appropriately completed for children admitted to the general paediatric wards at CHBAH.Methods. A retrospective review of discharge summaries completed for children admitted from 1 May to 31 July 2016 was undertaken. The completeness of the following demographic and clinical variables was assessed: patient identifiers, hospital outcome, HIV infection status and anthropometric status. The documentation of correct International Statistical Classification of Diseases and Related Health Problems, 10th revision (ICD-10) codes was assessed in children diagnosed with any form of lower respiratory tract infection (LRTI), which is the commonest diagnosis recorded in hospitalised children at CHBAH.Results. Discharge summaries were available for 1 148 (78.3%) of 1 466 children admitted during the study period. For completed discharge summaries, 80.1 - 93.3% of patient identifiers and 91.4% of patient outcomes were appropriately completed. HIV exposure was documented in 84.7% of summaries. Anthropometric parameters, including weight and length/height at admission and discharge weight, were appropriately completed in 91.4%, 70.9% and 50.0% of summaries, respectively. The ICD-10 code for children with LRTI was appropriately recorded by medical staff in 338 (67.2%) of 503 cases. ICD‑10 codes and anthropometric parameters, which are important clinical parameters in the paediatric follow-up consultation, were both correctly recorded for only 21.6% of children who required follow-up clinical consultations at CHBAH.Conclusions. Compared with similar studies, both the rate of completion and the quality of completed discharge summaries were modest in this tertiary academic teaching hospital. As discharge summaries are crucial medical documents, interventions to improve their completeness rate and quality need to be developed

COVID-19 antibody testing: From hype to immunological reality

The potential role for serological tests in the current COVID-19 pandemic has generated very considerable recent interest across many sectors worldwide, inter alia pathologists seeking additional weapons for their armoury of diagnostic tests; epidemiologists seeking tools to gain seroprevalence data that will inform improved models of the spread of disease; research scientists seeking tools to study the natural history of COVID-19 disease; vaccine developers seeking tools to assess vaccine efficacy in clinical trials; and companies and governments seeking tools to aid return-to-work decision-making. However, much of the local debate to date has centred on questions surrounding whether regulatory approval processes are limiting access to serological tests, and has not paused to consider the intrinsically limiting impact of underlying fundamental biology and immunology on where and how different COVID-19 serological tests can usefully be deployed in the response to the current pandemic. We review, from an immunological perspective, recent experimental evidence on the time-dependency of adaptive immune responses following SARS-CoV-2 infection and the impact of this on the sensitivity and specificity of COVID-19 antibody tests made at different time points post infection. We interpret this scientific evidence in terms of mooted clinical applications for current COVID-19 antibody tests in identifying acute infections, in confirming recent or past infections at the individual and population level, and in detecting re-infection and protective immunity. We conclude with guidance on where current COVID-19 antibody tests can make a genuine impact in the pandemic

Sepsis in previously healthy neonates discharged home after delivery in Soweto, South Africa

Background. There is a paucity of data on the aetiology of neonatal sepsis in sub-Saharan Africa.Objectives. To investigate the incidence, aetiology and outcomes of physician-diagnosed sepsis in hospitalised neonates who had previously been discharged home after delivery in Soweto, South Africa.Methods. A retrospective review using data abstracted from clinical and laboratory databases identified physician-diagnosed sepsis cases in neonates admitted to the general paediatric wards at Chris Hani Baragwanath Academic Hospital from January 2015 to September 2016. Neonates with physician-diagnosed sepsis were categorised into two groups based on putative pathogens recovered from blood and/or cerebrospinal fluid specimens: (i) culture-confirmed sepsis; and (ii) culture-negative sepsis.Results. Of 1 826 neonatal admissions, 1 025 (56.2%) had physician-diagnosed sepsis: 166 (16.2%) with culture-confirmed sepsis and 859 (83.8%) with culture-negative neonatal sepsis. The commonest pathogens causing culture-confirmed neonatal sepsis were Streptococcus viridans (n=53; 26.5%), S. agalactiae (n=38; 19.0%), and Staphylococcus aureus (n=25; 12.5%). The case fatality rates for culture-confirmed sepsis and culture-negative sepsis were 10.8% (18/166) and 2.6% (22/859), respectively. The odds of death occurring during hospitalisation was 10-fold (95% confidence interval 3.7 - 26.9) higher in neonates with culture-confirmed sepsis compared with culture-negative sepsis.Conclusions. In our setting, physician-diagnosed sepsis represents a huge disease burden in previously healthy neonates hospitalised from home. Most sepsis cases were attributed to S. viridans, S. agalactiae and S. aureus