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

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

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

A call to action: Temporal trends of COVID-19 deaths in the South African Muslim community

Letter by Omar on letter by Jassat et al. (Jassat W, Brey Z, Parker S, et al. A call to action: Temporal trends of COVID-19 deaths in the South African Muslim community. S Afr Med J 2021;111(8):692-694. https://doi.org/10.7196/SAMJ.2021.v111i8.15878); and response by Jassat et al

Antimicrobial susceptibility and serotype distribution of Streptococcus agalactiae rectovaginal colonising isolates from pregnant women at a tertiary hospital in Pretoria, South Africa: An observational descriptive study

Background. Streptococcus agalactiae or group B streptococcus (GBS) is a significant cause of neonatal sepsis. Intrapartum antibiotic prophylaxis is recommended for pregnant women identified to be rectovaginally colonised between 34 and 37 weeks’ gestational age to decrease the risk of invasive disease in their newborns. An effective multivalent GBS vaccine may prevent a broader scope of GBS-associated diseases, such as GBS early-onset disease, GBS late-onset disease, spontaneous abortion, stillbirth and maternal bacteraemia. Serotype distribution of GBS isolates is essential to determine the efficacy of such a vaccine.Objectives. To investigate serotype distribution and antimicrobial susceptibility patterns of GBS isolates cultured from rectovaginal specimens during pregnancy.Methods. Sixty-nine archived maternal colonising isolates were tested against penicillin, erythromycin, clindamycin, vancomycin and levofloxacin. Minimum inhibitory concentration testing was performed using the ETEST method. Serotyping was performed by the latex agglutination method.Results. The most common serotypes detected were Ia (54%), III (20%), V (16%), II (6%), IV (2%) and Ib (1%). All isolates were fully susceptible to penicillin, vancomycin and levofloxacin. Eight (11%) and 50 (56%) isolates showed intermediate resistance to erythromycin and clindamycin, respectively, and 1 isolate was resistant to erythromycin. The macrolide-lincosamide-streptogramin B (MLSB) phenomenon was noted in 3 (4%) of the isolates.Conclusions. GBS-colonising isolates remain susceptible to penicillin, which remains the drug of choice for intrapartum antibiotic prophylaxis and treatment of invasive disease in newborns. Macrolides should only be used if clinically indicated due to the high prevalence of intermediate resistance. A pentavalent GBS vaccine currently in phase I trials should provide coverage for 97% of the isolates identified in this study

Effectiveness of pneumococcal conjugate vaccine and rotavirus vaccine introduction into the South African public immunisation programme

Immunisation has contributed greatly to the control of vaccine-preventable diseases and therefore to improvements in health and survival, especially among young children, and remains one of the most successful and cost-effective public health interventions. This remains true for many of the newer, more expensive vaccines. Vaccines against invasive pneumococcal disease and rotavirus infection were introduced into the South African Expanded Programme on Immunization in April 2009. This article describes the rationale for and process of the introduction of these two vaccines, pneumococcal conjugate vaccine and rotavirus vaccine. It also aims to evaluate the success of and challenges related to their introduction, in terms of both achieving universal coverage and improving survival and health in South African children.

COVID-19 vaccines – less obfuscation, more transparency and action

Letter by Venter et al. on editorial  by Schoub (Dial down the rhetoric over COVID-19 vaccines. S Afr Med J 2021;111(6):522-523. https://doi.org/10.7196/SAMJ.2021.v111i6.15740)

Longitudinal Analysis of QuantiFERON-TB Gold In-Tube in Children with Adult Household Tuberculosis Contact in South Africa: A Prospective Cohort Study

QuantiFERON-TB Gold In Tube (QFT-GIT) is a tool for detecting M. tuberculosis infection. However, interpretation and utility of serial QFT-GIT testing of pediatric tuberculosis (TB) contacts is not well understood. We compared TB prevalence between baseline and 6 months follow-up using QFT-GIT and tuberculin skin testing (TST) in children who were household contacts of adults with pulmonary TB in South Africa, and explored factors associated with QFT-GIT conversions and reversions.Prospective study with six month longitudinal follow-up.Among 270 enrolled pediatric contacts, 196 (73%) underwent 6-month follow-up testing. The 6-month prevalence estimate of MTB infection in pediatric contacts increased significantly from a baseline of 29% (79/270, 95%CI [24-35]) to 38% (103/270, 95% CI [32-44], p<0.001) using QFT-GIT; prevalence increased from a baseline of 28% (71/254, 95%CI [23-34]) to 33% (88/263, 95%CI [21-32], p = 0.002) using TST. Prevalence estimates were influenced by thresholds for positivity for TST, but not for QFT-GIT. Among 134 children with a negative or indeterminate baseline QFT-GIT, 24 (18%) converted to positive at follow-up; conversion rates did not differ significantly when using more stringent thresholds to define QFT-GIT conversion. Older age >10 years (AOR 8.9 95%CI [1.1-72]) and baseline TST positivity ≥5 mm (AOR 5.2 95%CI [1.2-23]) were associated with QFT-GIT conversion. Among 62 children with a positive baseline QFT-GIT, 9 (15%) reverted to negative; female gender (AOR 18.5 95%CI [1.1-321]; p = 0.04] was associated with reversion, while children with baseline positive TST were less likely to have QFT-GIT reversion (AOR 0.01 95%CI [0.001-0.24]).Among pediatric contacts of adult household TB cases in South Africa, prevalence estimates of TB infection increased significantly from baseline to 6 months. Conversions and reversions occurred among pediatric TB contacts using QFT-GIT, but QFT-GIT conversion rates were less influenced by thresholds used for conversions than were TST conversion rates