Three-quarters attack rate of SARS-CoV-2 in the Brazilian Amazon during a largely unmitigated epidemic
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Abstract
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) incidence peaked in Manaus, Brazil, in May 2020 with a devastating toll on the city's inhabitants, leaving its health services shattered and cemeteries overwhelmed. Buss et al. collected data from blood donors from Manaus and São Paulo, noted when transmission began to fall, and estimated the final attack rates in October 2020 (see the Perspective by Sridhar and Gurdasani). Heterogeneities in immune protection, population structure, poverty, modes of public transport, and uneven adoption of nonpharmaceutical interventions mean that despite a high attack rate, herd immunity may not have been achieved. This unfortunate city has become a sentinel for how natural population immunity could influence future transmission. Events in Manaus reveal what tragedy and harm to society can unfold if this virus is left to run its course.
Science , this issue p. 288 ; see also p. 230
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SciScore for 10.1101/2020.09.16.20194787: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
NIH rigor criteria are not applicable to paper type.Table 2: Resources
Antibodies Sentences Resources The spatial distribution of blood donors tested in the study is shown in Fig. S6. Abbott SARS-CoV-2 IgG chemiluminescence microparticle assay: We used the Abbott SARS-CoV-2 chemiluminescence microparticle assay (CMIA) that detects IgG antibody against SARS-CoV-2 nucleocapsid protein. SARS-CoV-2 nucleocapsid protein.suggested: NoneThe chemiluminescence reaction is measured in relative light units (RLU) that increase as a function of the amount of anti-SARS-CoV-2 IgG antibodies present in the sample. anti-SARS-CoV-2 IgGsuggested: NoneQuantifying antibody waning and rate of seroreversion: We sought to … SciScore for 10.1101/2020.09.16.20194787: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
NIH rigor criteria are not applicable to paper type.Table 2: Resources
Antibodies Sentences Resources The spatial distribution of blood donors tested in the study is shown in Fig. S6. Abbott SARS-CoV-2 IgG chemiluminescence microparticle assay: We used the Abbott SARS-CoV-2 chemiluminescence microparticle assay (CMIA) that detects IgG antibody against SARS-CoV-2 nucleocapsid protein. SARS-CoV-2 nucleocapsid protein.suggested: NoneThe chemiluminescence reaction is measured in relative light units (RLU) that increase as a function of the amount of anti-SARS-CoV-2 IgG antibodies present in the sample. anti-SARS-CoV-2 IgGsuggested: NoneQuantifying antibody waning and rate of seroreversion: We sought to quantify the rate of decline of the anti-nucleocapsid IgG antibody that is detected by the Abbott CMIA. anti-nucleocapsid IgGsuggested: NoneAnalysis of seroprevalence data: Using the manufacturer’s threshold of 1.4 S/C to define a positive result we first calculated the monthly crude prevalence of anti-SARS-CoV-2 antibodies as the number of positive samples/total samples tested. anti-SARS-CoV-2suggested: NoneSoftware and Algorithms Sentences Resources To address this issue, we performed a local validation of the Abbott CIMA on a range of clinical samples. Abbottsuggested: (Abbott, RRID:SCR_010477)Results from OddPub: Thank you for sharing your code and data.
Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:Despite this limitation of the Abbott assay, one potential advantage to the decay in signal over time is to monitor for reinfections at the population level in the case of a second epidemic wave based on boosting of seroreactivity. Indeed, Manaus may act as a sentinel to determine the longevity of population immunity and frequency of reinfections. An additional strategy to antibody surveillance would be monitoring of local versus imported cases, with a relative increase in local cases suggesting population immunity was no longer preventing onwards transmission. Another important limitation is the extent to which blood donors are representative of the wider population with respect to SARS-CoV-2 exposure. Firstly, children and the elderly are excluded from blood donation. The eligible age range for blood donation in Brazil (16 - 69yr), as well as sex distributions in donors, are different from the underlying populations in both cities (Fig. S4); however, we attempted to account for this by re-weighting according to age and sex. Furthermore, only healthy asymptomatic adults without a recent history of COVID-19 infection are eligible to donate blood. This would be expected to lead to an underestimation of true prevalence – the healthy volunteer donor effect. It is reassuring that a household survey in São Paulo city, employing a random sampling strategy and comparable antibody assay, found very similar results to our study: 4.7% seroprevalence in May 29 (versus 5.3% in blood dono...
Results from TrialIdentifier: No clinical trial numbers were referenced.
Results from Barzooka: We did not find any issues relating to the usage of bar graphs.
Results from JetFighter: We did not find any issues relating to colormaps.
Results from rtransparent:- Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
- Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
- Thank you for including a protocol registration statement.
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Cesar Victora
Review 1: "COVID-19 herd immunity in the Brazilian Amazon"
This preprint is an important contribution to literature on the interpretation of seroprevalence estimates. The use of blood donors as the sample may have biased the result & the authors' suggestion that Manaus may have reached herd immunity is at odds with the increase in cases.
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Strength of evidence
Reviewers: Cesar Victora (Federal University of Pelotas) | 📒📒📒◻️◻️
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SciScore for 10.1101/2020.09.16.20194787: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
NIH rigor criteria are not applicable to paper type.Table 2: Resources
Antibodies Sentences Resources Prevalence of SARS-CoV-2 antibodies in Manaus and São Paulo In order to estimate the proportion of the population with antibodies against SARS-CoV-2, we used a convenience sample of routine blood donations made at the Fundação Pró-Sangue blood bank in São Paulo and the Fundação Hospitalar de Hematologia e Hemoterapia do Amazonas (HEMOAM) in Manaus. SARS-CoV-2suggested: NoneSoftware and Algorithms Sentences Resources SARS-CoV-2 antibody dynamics and serology assay validation We used a … SciScore for 10.1101/2020.09.16.20194787: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
NIH rigor criteria are not applicable to paper type.Table 2: Resources
Antibodies Sentences Resources Prevalence of SARS-CoV-2 antibodies in Manaus and São Paulo In order to estimate the proportion of the population with antibodies against SARS-CoV-2, we used a convenience sample of routine blood donations made at the Fundação Pró-Sangue blood bank in São Paulo and the Fundação Hospitalar de Hematologia e Hemoterapia do Amazonas (HEMOAM) in Manaus. SARS-CoV-2suggested: NoneSoftware and Algorithms Sentences Resources SARS-CoV-2 antibody dynamics and serology assay validation We used a commercially available chemiluminescence assay (CIMA) that detects IgG antibody against the SARS-CoV-2 nucleocapsid (N) protein (Abbott, Chicago, USA). Abbottsuggested: (Abbott, RRID:SCR_010477)Results from OddPub: Thank you for sharing your code and data.
Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:
Despite this limitation of the Abbott assay, one potential advantage to the decay in signal over time is to monitor for reinfections at the population level in the case of a second epidemic wave based on boosting of seroreactivity. Indeed, Manaus may act as a sentinel to determine the longevity of population immunity and frequency of reinfections. An additional strategy to antibody surveillance would be monitoring of local versus imported cases, with a relative increase in local cases suggesting population immunity was no longer preventing onwards transmission. Another important limitation is the extent to which blood donors are representative of the wider population with respect to SARS-CoV-2 exposure. Firstly, children and the elderly are excluded from blood donation. The eligible age range for blood donation in Brazil (16 69yr), as well as sex distributions in donors, are different from the underlying populations in both cities (Fig. S4); however, we attempted to account for this by re-weighting according to age and sex. Furthermore, only healthy asymptomatic adults without a recent history of COVID-19 infection are eligible to donate blood. This would be expected to lead to an underestimation of true prevalence – the healthy volunteer donor effect. It is reassuring that a household survey in São Paulo city, employing a random sampling strategy and comparable antibody assay, found very similar results to our study: 4.7% seroprevalence in May 29 (versus 5.3% in blood donors...
Results from TrialIdentifier: No clinical trial numbers were referenced.
Results from Barzooka: We did not find any issues relating to the usage of bar graphs.
Results from JetFighter: We did not find any issues relating to colormaps.
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