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 COVID19, 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 COVID19 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

Children caught in the long shadow of COVID-19

Despite the more transmissible delta variant being associated with higher rates of COVID-19 in unvaccinated adolescents, children have remained relatively spared from severe disease. Nevertheless, children are indirectly affected by the COVID-19 pandemic, which threatens to have far-reaching consequences. The effect of disruptions of seasonal patterns of circulation of respiratory pathogens on future immunity against such pathogens, childhood immunization programmes, and HIV and tuberculosis treatment programmes poses a threat to the future wellbeing of children. Furthermore, the economic devastation caused by the pandemic, including an increase in unemployment, gives rise to numerous challenges, such as food insecurity, which is likely to worsen childhood nutritional status. Also, COVID-19 has ongoing effects on the mental wellbeing of children, driven in part by the interruption of schooling and other opportunities to socialize. An increase in psychological illnesses has manifested in children consequent to the stresses of the pandemic, lockdowns, caregiver deaths. In this article, we highlight the indirect effects of COVID-19 on children, and suggest solutions to mitigate against the long-term sequelae. A focused health, nutrition, education and child protection response is required from government and healthcare practitioners to safeguard the health and wellbeing of South African children.

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

Diagnosis and Management of Community-Acquired Pneumonia in Childhood - South African Thoracic Society Guidelines

Background: Community-acquired pneumonia (CAP) is a major cause of morbidity and mortality in South African children. The incidence; severity and spectrum of childhood pneumonia have changed owing to the HIV epidemic. Increasing emergence of antimicrobial resistance necessitates a rational approach to the use of antibiotics in pneumonia management. Objective: To develop guidelines for the diagnosis; management and prevention of CAP in South African children. Methods: The Paediatric Assembly of the South African Thoracic Society established five expert subgroups to address: (i) epidemiology and aetiology; (ii) diagnosis; (iii) antibiotic treatment; (iv) supportive therapy; and (v) prevention of CAP. Each subgroup developed a position paper based on the available published evidence; in the absence of evidence; expert opinion was accepted. After peer review and revision; the position papers were synthesised into an overall guideline which was further reviewed and revised. Recommendations: Recommendations based on epidemiological factors include a diagnostic approach; investigations; supportive therapy; appropriate antibiotic treatment and preventive strategies. Specific recommendations for HIV-infected children are provided. Validation: These guidelines are based on the available evidence supplemented by the consensus opinion of South African experts in aediatrics; paediatric pulmonology; radiology; infectious diseases and microbiology. Published international guidelines have also been consulted

Introduction of the Pneumococcal Conjugate Vaccine into the South African Public Immunisation Programme: Dawn of a New Era?

Streptococcus pneumoniae is a leading vaccine-preventable cause of childhood death with an estimated 716;000 deaths occurring annually. Recent advances have seen the development of vaccines targeted against S. pneumoniae that are immunogenic and efficacious in very young children. These pneumococcal conjugate vaccines have now been evaluated in developed and industrialising countries with consistent efficacy against invasive pneumococcal disease at least due to the serotypes included in the vaccine. The vaccine has also been efficacious in preventing radiographically confirmed pneumonia; but has had less effect on pneumococcal acute otitis media. The introduction of the vaccine into the USA has been greatly successful and exceeds its expectations based upon the vaccine efficacy trials. In addition to preventing a greater than expected burden of invasive disease and pneumonia than anticipated in vaccinated children; the vaccine has also been associated with marked reduction in pneumococcal disease among unvaccinated members of the population; referred to as `indirect protection'. The introduction of the vaccine into the immunisation programme of industrialising countries; such as in South Africa; require robust surveillance to evaluate the effectiveness of the vaccine in such settings where the epidemiology of pneumococcal diseases differs to that in developed countries