Estimated SARS-CoV-2 infection rate and fatality risk in Gauteng Province, South Africa: a population-based seroepidemiological survey.

Limitations in laboratory testing capacity undermine the ability to quantify the overall burden of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection. We undertook a population-based serosurvey for SARS-CoV-2 infection in 26 subdistricts, Gauteng Province (population 15.9 million), South Africa, to estimate SARS-CoV-2 infection, infection fatality rate (IFR) triangulating seroprevalence, recorded COVID-19 deaths and excess-mortality data. We employed three-stage random household sampling with a selection probability proportional to the subdistrict size, stratifying the subdistrict census-sampling frame by housing type and then selecting households from selected clusters. The survey started on 4 November 2020, 8 weeks after the end of the first wave (SARS-CoV-2 nucleic acid amplification test positivity had declined to <10% for the first wave) and coincided with the peak of the second wave. The last sampling was performed on 22 January 2021, which was 9 weeks after the SARS-CoV-2 resurgence. Serum SARS-CoV-2 receptor-binding domain (RBD) immunoglobulin-G (IgG) was measured using a quantitative assay on the Luminex platform. From 6332 individuals in 3453 households, the overall RBD IgG seroprevalence was 19.1% [95% confidence interval (CI): 18.1-20.1%] and similar in children and adults. The seroprevalence varied from 5.5% to 43.2% across subdistricts. Conservatively, there were 2 897 120 (95% CI: 2 743 907-3 056 866) SARS-CoV-2 infections, yielding an infection rate of 19 090 per 100 000 until 9 January 2021, when 330 336 COVID-19 cases were recorded. The estimated IFR using recorded COVID-19 deaths (n = 8198) was 0.28% (95% CI: 0.27-0.30) and 0.67% (95% CI: 0.64-0.71) assuming 90% of modelled natural excess deaths were due to COVID-19 (n = 21 582). Notably, 53.8% (65/122) of individuals with previous self-reported confirmed SARS-CoV-2 infection were RBD IgG seronegative. The calculated number of SARS-CoV-2 infections was 7.8-fold greater than the recorded COVID-19 cases. The calculated SARS-CoV-2 IFR varied 2.39-fold when calculated using reported COVID-19 deaths (0.28%) compared with excess-mortality-derived COVID-19-attributable deaths (0.67%). Waning RBD IgG may have inadvertently underestimated the number of SARS-CoV-2 infections and conversely overestimated the mortality risk. Epidemic preparedness and response planning for future COVID-19 waves will need to consider the true magnitude of infections, paying close attention to excess-mortality trends rather than absolute reported COVID-19 deaths.

Mutevedzi PC ，Kawonga M ，Kwatra G ，Moultrie A ，Baillie V ，Mabena N ，Mathibe MN ，Rafuma MM ，Maposa I ，Abbott G ，Hugo J ，Ikalafeng B ，Adelekan T ，Lukhele M ，Madhi SA ... -  《-》

Population Immunity and Covid-19 Severity with Omicron Variant in South Africa.

The B.1.1.529 (omicron) variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was first identified on November 25, 2021, in Gauteng province, South Africa. Data regarding the seroprevalence of SARS-CoV-2 IgG in Gauteng before the fourth wave of coronavirus disease 2019 (Covid-19), in which the omicron variant was dominant, are needed. We conducted a seroepidemiologic survey from October 22 to December 9, 2021, in Gauteng to determine the seroprevalence of SARS-CoV-2 IgG. Households included in a previous seroepidemiologic survey (conducted from November 2020 to January 2021) were contacted; to account for changes in the survey population, there was a 10% increase in the households contacted, with the use of the same sampling framework. Dried-blood-spot samples were tested for IgG against SARS-CoV-2 spike protein and nucleocapsid protein with the use of quantitative assays. We also evaluated Covid-19 epidemiologic trends in Gauteng, including cases, hospitalizations, recorded deaths, and excess deaths from the start of the pandemic through January 12, 2022. Samples were obtained from 7010 participants, of whom 1319 (18.8%) had received a Covid-19 vaccine. The seroprevalence of SARS-CoV-2 IgG ranged from 56.2% (95% confidence interval [CI], 52.6 to 59.7) among children younger than 12 years of age to 79.7% (95% CI, 77.6 to 81.5) among adults older than 50 years of age. Vaccinated participants were more likely to be seropositive for SARS-CoV-2 than unvaccinated participants (93.1% vs. 68.4%). Epidemiologic data showed that the incidence of SARS-CoV-2 infection increased and subsequently declined more rapidly during the fourth wave than it had during the three previous waves. The incidence of infection was decoupled from the incidences of hospitalization, recorded death, and excess death during the fourth wave, as compared with the proportions seen during previous waves. Widespread underlying SARS-CoV-2 seropositivity was observed in Gauteng before the omicron-dominant wave of Covid-19. Epidemiologic data showed a decoupling of hospitalizations and deaths from infections while omicron was circulating. (Funded by the Bill and Melinda Gates Foundation.).

Madhi SA ，Kwatra G ，Myers JE ，Jassat W ，Dhar N ，Mukendi CK ，Nana AJ ，Blumberg L ，Welch R ，Ngorima-Mabhena N ，Mutevedzi PC ... -  《-》

Prevalence of SARS-CoV-2 infection in India: Findings from the national serosurvey, May-June 2020.

Murhekar MV ，Bhatnagar T ，Selvaraju S ，Rade K ，Saravanakumar V ，Vivian Thangaraj JW ，Kumar MS ，Shah N ，Sabarinathan R ，Turuk A ，Anand PK ，Asthana S ，Balachandar R ，Bangar SD ，Bansal AK ，Bhat J ，Chakraborty D ，Rangaraju C ，Chopra V ，Das D ，Deb AK ，Devi KR ，Dwivedi GR ，Salim Khan SM ，Haq I ，Kumar MS ，Laxmaiah A ，Madhuka ，Mahapatra A ，Mitra A ，Nirmala AR ，Pagdhune A ，Qurieshi MA ，Ramarao T ，Sahay S ，Sharma YK ，Shrinivasa MB ，Shukla VK ，Singh PK ，Viramgami A ，Wilson VC ，Yadav R ，Girish Kumar CP ，Luke HE ，Ranganathan UD ，Babu S ，Sekar K ，Yadav PD ，Sapkal GN ，Das A ，Das P ，Dutta S ，Hemalatha R ，Kumar A ，Narain K ，Narasimhaiah S ，Panda S ，Pati S ，Patil S ，Sarkar K ，Singh S ，Kant R ，Tripathy S ，Toteja GS ，Babu GR ，Kant S ，Muliyil JP ，Pandey RM ，Sarkar S ，Singh SK ，Zodpey S ，Gangakhedkar RR ，S Reddy DC ，Bhargava B ... -  《-》

Infection fatality risk for SARS-CoV-2 in community dwelling population of Spain: nationwide seroepidemiological study.

To estimate the infection fatality risk for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), based on deaths with confirmed coronavirus disease 2019 (covid-19) and excess deaths from all causes. Nationwide seroepidemiological study. First wave of covid-19 pandemic in Spain. Community dwelling individuals of all ages. The main outcome measure was overall, and age and sex specific, infection fatality risk for SARS-CoV-2 (the number of covid-19 deaths and excess deaths divided by the estimated number of SARS-CoV-2 infections) in the community dwelling Spanish population. Deaths with laboratory confirmed covid-19 were obtained from the National Epidemiological Surveillance Network (RENAVE) and excess all cause deaths from the Monitoring Mortality System (MoMo), up to 15 July 2020. SARS-CoV-2 infections in Spain were derived from the estimated seroprevalence by a chemiluminescent microparticle immunoassay for IgG antibodies in 61 098 participants in the ENE-COVID nationwide seroepidemiological survey between 27 April and 22 June 2020. The overall infection fatality risk was 0.8% (19 228 of 2.3 million infected individuals, 95% confidence interval 0.8% to 0.9%) for confirmed covid-19 deaths and 1.1% (24 778 of 2.3 million infected individuals, 1.0% to 1.2%) for excess deaths. The infection fatality risk was 1.1% (95% confidence interval 1.0% to 1.2%) to 1.4% (1.3% to 1.5%) in men and 0.6% (0.5% to 0.6%) to 0.8% (0.7% to 0.8%) in women. The infection fatality risk increased sharply after age 50, ranging from 11.6% (8.1% to 16.5%) to 16.4% (11.4% to 23.2%) in men aged 80 or more and from 4.6% (3.4% to 6.3%) to 6.5% (4.7% to 8.8%) in women aged 80 or more. The increase in SARS-CoV-2 infection fatality risk after age 50 appeared to be more noticeable in men than in women. Based on the results of this study, fatality from covid-19 was greater than that reported for other common respiratory diseases, such as seasonal influenza.

Pastor-Barriuso R ，Pérez-Gómez B ，Hernán MA ，Pérez-Olmeda M ，Yotti R ，Oteo-Iglesias J ，Sanmartín JL ，León-Gómez I ，Fernández-García A ，Fernández-Navarro P ，Cruz I ，Martín M ，Delgado-Sanz C ，Fernández de Larrea N ，León Paniagua J ，Muñoz-Montalvo JF ，Blanco F ，Larrauri A ，Pollán M ，ENE-COVID Study Group ... -  《BMJ-British Medical Journal》

Sustained Low Incidence of Severe and Fatal COVID-19 Following Widespread Infection Induced Immunity after the Omicron (BA.1) Dominant in Gauteng, South Africa: An Observational Study.

Madhi SA ，Kwatra G ，Myers JE ，Jassat W ，Dhar N ，Mukendi CK ，Blumberg L ，Welch R ，Izu A ，Mutevedzi PC ... -  《Viruses-Basel》