Author
Michelle J. Groome
Other affiliations: Medical Research Council, National Research Foundation of South Africa, South African Medical Research Council
Bio: Michelle J. Groome is an academic researcher from University of the Witwatersrand. The author has contributed to research in topics: Medicine & Rotavirus vaccine. The author has an hindex of 24, co-authored 60 publications receiving 2813 citations. Previous affiliations of Michelle J. Groome include Medical Research Council & National Research Foundation of South Africa.
Papers
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University of Edinburgh1, University of Glasgow2, Johns Hopkins University3, University of Colorado Boulder4, University of the Witwatersrand5, International Military Sports Council6, Aga Khan University7, Medical Research Council8, King George's Medical University9, Kenya Medical Research Institute10, Centers for Disease Control and Prevention11, International Centre for Diarrhoeal Disease Research, Bangladesh12, Tribhuvan University13, University of Bergen14, University of Barcelona15, Utrecht University16, Emory University17, All India Institute of Medical Sciences18, University of Liverpool19, Boston Children's Hospital20, National Institute of Virology21, University of Zambia22, University of Health Sciences Antigua23, National Health Laboratory Service24, Chinese Center for Disease Control and Prevention25, Austral University26, University of Michigan27, Vanderbilt University28, University of New South Wales29, University of Otago30, University of Auckland31, Universidad del Valle de Guatemala32, University of Jordan33, University of Maryland, Baltimore34, National Scientific and Technical Research Council35, Research Institute for Tropical Medicine36, Pwani University College37, University of Cape Town38, University of Warwick39, Academy of Medical Sciences, United Kingdom40, Tohoku University41, École normale supérieure de Lyon42, John E. Fogarty International Center43, Charité44, Universidad Nacional de Asunción45, Tehran University of Medical Sciences46, Robert Koch Institute47, University of London48, University of New Mexico49, Capital Medical University50, Alaska Native Tribal Health Consortium51, Innlandet Hospital Trust52, Columbia University53, Mahidol University54, University of Pretoria55, Thailand Ministry of Public Health56, Peking Union Medical College57, Nagasaki University58, Public Health Foundation of India59
TL;DR: In this paper, the authors estimated the incidence and hospital admission rate of RSV-associated acute lower respiratory infection (RSV-ALRI) in children younger than 5 years stratified by age and World Bank income regions.
1,470 citations
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TL;DR: Analysis of routine surveillance data from South Africa indicates that the Omicron variant of SARS-CoV-2 evades immunity from prior infection, and this variant does not fully evade vaccine-derived immunity, but only those privileged to have been vaccinated can benefit.
Abstract: We provide two methods for monitoring reinfection trends in routine surveillance data to identify signatures of changes in reinfection risk and apply these approaches to data from South Africa’s severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) epidemic to date. Although we found no evidence of increased reinfection risk associated with circulation of the Beta (B.1.351) or Delta (B.1.617.2) variants, we did find clear, population-level evidence to suggest immune evasion by the Omicron (B.1.1.529) variant in previously infected individuals in South Africa. Reinfections occurring between 1 November 2021 and 31 January 2022 were detected in individuals infected in all three previous waves, and there has been an increase in the risk of having a third infection since mid-November 2021. Description Omicron and reinfection risk So far, our experience with pandemic coronavirus has been that the emergence of new variants is not detected until there has been substantial community transmission. Early in November 2021, South African scientists spotted reinfections consistent with the timing of the emergence of the Omicron variant (B.1.1.529). In a population largely untouched by vaccines but widely infected, Pulliam et al. found that Beta or Delta variants rarely caused reinfection. However, after 31 October 2021, individuals were found who had had three experiences of infection (see the Perspective by Zelner and Eisenberg). The culprit was the rapidly emerging Omicron variant, with multiple mutations in the Spike protein. This variant’s chief advantage is its ability to evade naturally acquired immunity. Fortunately, the Omicron variant does not fully evade vaccine-derived immunity, but only those privileged to have been vaccinated can benefit. —CA Analysis of routine surveillance data from South Africa indicates that the Omicron variant of SARS-CoV-2 evades immunity from prior infection. INTRODUCTION Globally, there have been more than 404 million cases of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), with 5.8 million confirmed deaths as of February 2022. South Africa has experienced four waves of SARS-CoV-2 transmission, with the second, third, and fourth waves being driven by the Beta, Delta, and Omicron variants, respectively. A key question with the emergence of new variants is the extent to which they are able to reinfect those who have had a prior natural infection. RATIONALE We developed two approaches to monitor routine epidemiological surveillance data to determine whether SARS-CoV-2 reinfection risk has changed through time in South Africa in the context of the emergence of the Beta (B.1.351), Delta (B.1.617.2), and Omicron (B.1.1.529) variants. We analyzed line-list data on positive tests for SARS-CoV-2 with specimen receipt dates between 4 March 2020 and 31 January 2022 collected through South Africa’s National Notifiable Medical Conditions Surveillance System. Individuals having sequential positive tests at least 90 days apart were considered to have suspected reinfections. Our routine monitoring of reinfection risk included comparison of reinfection rates with the expectation under a null model (approach 1) and estimation of the time-varying hazards of infection and reinfection throughout the epidemic (approach 2) based on model-based reconstruction of the susceptible populations eligible for primary and second infections. RESULTS A total of 105,323 suspected reinfections were identified among 2,942,248 individuals with laboratory-confirmed SARS-CoV-2 who had a positive test result at least 90 days before 31 January 2022. The number of reinfections observed through the end of the third wave in September 2021 was consistent with the null model of no change in reinfection risk (approach 1). Although increases in the hazard of primary infection were observed after the introduction of both the Beta and Delta variants, no corresponding increase was observed in the reinfection hazard (approach 2). Contrary to expectation, the estimated hazard ratio for reinfection versus primary infection was lower during waves driven by the Beta and Delta variants than for the first wave: the relative hazard ratio for wave 2 versus wave 1 was 0.71 [95% confidence interval (95% CI): 0.60 to 0.85]; the relative hazard ratio for wave 3 versus wave 1 was 0.54 (95% CI: 0.45 to 0.64). By contrast, the recent spread of the Omicron variant has been associated with an increase in reinfection hazard coefficient. The estimated relative hazard ratio for reinfection versus primary infection versus wave 1 was 1.75 (95% CI: 1.48 to 2.10) for the period of Omicron emergence (1 November 2021 to 30 November 2021) and 1.70 (95% CI: 1.44 to 2.04) for wave 4 versus wave 1. Individuals with identified reinfections since 1 November 2021 had experienced primary infections in all three prior waves, and an increase in third infections has been detected since mid-November 2021. Many individuals experiencing third infections had second infections during the third (Delta) wave that ended in September 2021, strongly suggesting that these infections resulted from immune evasion rather than waning immunity. CONCLUSION Population-level evidence suggests that the Omicron variant is associated with a marked ability to evade immunity from prior infection. In contrast, there is no population-wide epidemiological evidence of immune escape associated with the Beta or Delta variants. This finding has important implications for public health planning, particularly in countries such as South Africa with high rates of immunity from prior infection. The further development of methods to track reinfection risk during pathogen emergence, including refinements to assess the impact of waning immunity, account for vaccine-derived protection, and monitor the risk of multiple reinfections, will be important for future pandemic preparedness. SARS-CoV-2 reinfection patterns in South Africa. South Africa has experienced four waves of SARS-CoV-2 transmission, each driven by the emergence of a new variant. Reinfection of previously infected individuals was relatively rare through the end of the third wave. Methods developed in South Africa to monitor reinfection trends led to the early detection of increased reinfection risk associated with the Omicron variant.
587 citations
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TL;DR: COVID-19 vaccine efficacy or effectiveness against severe disease remained high, although it did decrease somewhat by 6 months after full vaccination, and the decrease is likely caused by, at least in part, waning immunity.
449 citations
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University of Edinburgh1, Johns Hopkins University2, University of the Witwatersrand3, Centers for Disease Control and Prevention4, Institute of Tropical Medicine Antwerp5, Umeå University6, Yale University7, Aga Khan University8, University of Michigan9, University of Turku10, Universidad del Valle de Guatemala11, Ben-Gurion University of the Negev12, Clalit Health Services13, University of Jordan14, All India Institute of Medical Sciences15, Generalitat Valenciana16, Wellcome Trust17, National Institutes of Health18, Colorado School of Public Health19, Anschutz Medical Campus20, Thailand Ministry of Public Health21, Nagasaki University22, University of Cape Town23
TL;DR: The findings provide new and important evidence for maternal and paediatric influenza immunisation, and should inform future immunisation policy particularly in low-income and lower-middle-income countries.
203 citations
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University Medical Center Utrecht1, Boston Children's Hospital2, University of Warwick3, Kenya Medical Research Institute4, Pwani University College5, University of the Witwatersrand6, Centers for Disease Control and Prevention7, Tohoku University8, Research Institute for Tropical Medicine9, University of Michigan10, Johns Hopkins University11, Ohio State University12, Nationwide Children's Hospital13, University of Jordan14, Vanderbilt University Medical Center15, University of Virginia16, McMaster University17, University of Colorado Boulder18, The Chinese University of Hong Kong19, Royal Children's Hospital20, University of Melbourne21, Aga Khan University22, University of Nottingham23, McGill University Health Centre24, University of Sheffield25, Utrecht University26, University of Edinburgh27
TL;DR: The results show that perinatal immunisation strategies for children aged younger than 6 months could have a substantial impact on RSV-related child mortality in low-income and middle-income countries.
180 citations
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TL;DR: It is found that interventions aimed at children might have a relatively small impact on reducing SARS-CoV-2 transmission, particularly if the transmissibility of subclinical infections is low.
Abstract: The COVID-19 pandemic has shown a markedly low proportion of cases among children1–4. Age disparities in observed cases could be explained by children having lower susceptibility to infection, lower propensity to show clinical symptoms or both. We evaluate these possibilities by fitting an age-structured mathematical model to epidemic data from China, Italy, Japan, Singapore, Canada and South Korea. We estimate that susceptibility to infection in individuals under 20 years of age is approximately half that of adults aged over 20 years, and that clinical symptoms manifest in 21% (95% credible interval: 12–31%) of infections in 10- to 19-year-olds, rising to 69% (57–82%) of infections in people aged over 70 years. Accordingly, we find that interventions aimed at children might have a relatively small impact on reducing SARS-CoV-2 transmission, particularly if the transmissibility of subclinical infections is low. Our age-specific clinical fraction and susceptibility estimates have implications for the expected global burden of COVID-19, as a result of demographic differences across settings. In countries with younger population structures—such as many low-income countries—the expected per capita incidence of clinical cases would be lower than in countries with older population structures, although it is likely that comorbidities in low-income countries will also influence disease severity. Without effective control measures, regions with relatively older populations could see disproportionally more cases of COVID-19, particularly in the later stages of an unmitigated epidemic. A new epidemiological study shows reduced susceptibility to SARS-CoV-2 and decreased risk of developing severe symptoms in people aged younger than 20 years, suggesting that children have limited contribution to spread of COVID-19.
1,281 citations
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Christopher Troeger1, Brigette F. Blacker1, Ibrahim A Khalil1, Puja C Rao1 +148 more•Institutions (28)
TL;DR: The findings show substantial progress in the reduction of lower respiratory infection burden, but this progress has not been equal across locations, has been driven by decreases in several primary risk factors, and might require more effort among elderly adults.
Abstract: Summary Background Lower respiratory infections are a leading cause of morbidity and mortality around the world The Global Burden of Diseases, Injuries, and Risk Factors (GBD) Study 2016, provides an up-to-date analysis of the burden of lower respiratory infections in 195 countries This study assesses cases, deaths, and aetiologies spanning the past 26 years and shows how the burden of lower respiratory infection has changed in people of all ages Methods We used three separate modelling strategies for lower respiratory infections in GBD 2016: a Bayesian hierarchical ensemble modelling platform (Cause of Death Ensemble model), which uses vital registration, verbal autopsy data, and surveillance system data to predict mortality due to lower respiratory infections; a compartmental meta-regression tool (DisMod-MR), which uses scientific literature, population representative surveys, and health-care data to predict incidence, prevalence, and mortality; and modelling of counterfactual estimates of the population attributable fraction of lower respiratory infection episodes due to Streptococcus pneumoniae, Haemophilus influenzae type b, influenza, and respiratory syncytial virus We calculated each modelled estimate for each age, sex, year, and location We modelled the exposure level in a population for a given risk factor using DisMod-MR and a spatio-temporal Gaussian process regression, and assessed the effectiveness of targeted interventions for each risk factor in children younger than 5 years We also did a decomposition analysis of the change in LRI deaths from 2000–16 using the risk factors associated with LRI in GBD 2016 Findings In 2016, lower respiratory infections caused 652 572 deaths (95% uncertainty interval [UI] 586 475–720 612) in children younger than 5 years (under-5s), 1 080 958 deaths (943 749–1 170 638) in adults older than 70 years, and 2 377 697 deaths (2 145 584–2 512 809) in people of all ages, worldwide Streptococcus pneumoniae was the leading cause of lower respiratory infection morbidity and mortality globally, contributing to more deaths than all other aetiologies combined in 2016 (1 189 937 deaths, 95% UI 690 445–1 770 660) Childhood wasting remains the leading risk factor for lower respiratory infection mortality among children younger than 5 years, responsible for 61·4% of lower respiratory infection deaths in 2016 (95% UI 45·7–69·6) Interventions to improve wasting, household air pollution, ambient particulate matter pollution, and expanded antibiotic use could avert one under-5 death due to lower respiratory infection for every 4000 children treated in the countries with the highest lower respiratory infection burden Interpretation Our findings show substantial progress in the reduction of lower respiratory infection burden, but this progress has not been equal across locations, has been driven by decreases in several primary risk factors, and might require more effort among elderly adults By highlighting regions and populations with the highest burden, and the risk factors that could have the greatest effect, funders, policy makers, and programme implementers can more effectively reduce lower respiratory infections among the world's most susceptible populations Funding Bill & Melinda Gates Foundation
1,147 citations
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Johns Hopkins University1, Brigham and Women's Hospital2, Save the Children3, University of London4, Imperial College London5, Aga Khan University6, University of North Carolina at Chapel Hill7, Universidade Federal de Pelotas8, Harvard University9, Pontifical Catholic University of Chile10, Ghent University11, Mahidol University12, University of Los Andes13, UCL Institute of Child Health14, Copenhagen University Hospital15, University of Copenhagen16, George Washington University17, University of the Witwatersrand18
TL;DR: Differentiation of the burden and risk of babies born preterm and SGA rather than with low birthweight could guide prevention and management strategies to speed progress towards Millennium Development Goal 4--the reduction of child mortality.
660 citations
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TL;DR: It is found that interventions aimed at children may have a relatively small impact on total cases, particularly if the transmissibility of subclinical infections is low, and the expected clinical attack rate would be lower in younger populations than in older populations.
Abstract: The COVID-19 pandemic has shown a markedly low proportion of cases among children. Age disparities in observed cases could be explained by assortative mixing patterns and reactive school closures which decrease mixing between children, or by children exhibiting lower susceptibility to infection, or by children having a lower propensity to show clinical symptoms. We formally test these hypotheses by fitting an age-structured mathematical model to epidemic data from six countries, finding strong age dependence in the probability of developing clinical symptoms, rising from around 20% in under 10s to over 70% in older adults. We find that interventions aimed at halting transmission in children may have minimal effects on preventing cases depending on the relative transmissibility of subclinical infections. Our estimated age-specific clinical fraction has implications for the expected global burden of clinical cases because of demographic differences across settings. In younger populations, the expected clinical attack rate would be lower, although it is likely that comorbidities in low-income countries will affect disease severity. Without effective control measures, regions with older populations may see disproportionally more clinical cases, particularly in the later stages of the pandemic.
645 citations
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TL;DR: In this paper , the authors reported that the Omicron spike was resistant against most therapeutic antibodies but remained susceptible to inhibition by sotrovimab, and that double immunization with BNT162b2 might not adequately protect against severe disease induced by this variant.
603 citations