Contact tracing of COVID-19 in Karnataka, India: Superspreading and determinants of infectiousness and symptomatic infection
<h4>Background</h4> India has experienced the second largest outbreak of COVID-19 globally, yet there is a paucity of studies analysing contact tracing data in the region which can optimise public health interventions (PHI’s). <h4>Methods</h4> We analysed contact tracing data...
| Main Authors: | , , , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
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Public Library of Science (PLoS)
2022-01-01
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| Series: | PLoS ONE |
| Online Access: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9273085/?tool=EBI |
| _version_ | 1818005718998974464 |
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| author | Mohak Gupta Giridara G. Parameswaran Manraj S. Sra Rishika Mohanta Devarsh Patel Amulya Gupta Bhavik Bansal Vardhmaan Jain Archisman Mazumder Mehak Arora Nishant Aggarwal Tarun Bhatnagar Jawaid Akhtar Pankaj Pandey Vasanthapuram Ravi Giridhara R. Babu |
| author_facet | Mohak Gupta Giridara G. Parameswaran Manraj S. Sra Rishika Mohanta Devarsh Patel Amulya Gupta Bhavik Bansal Vardhmaan Jain Archisman Mazumder Mehak Arora Nishant Aggarwal Tarun Bhatnagar Jawaid Akhtar Pankaj Pandey Vasanthapuram Ravi Giridhara R. Babu |
| author_sort | Mohak Gupta |
| collection | DOAJ |
| description | <h4>Background</h4> India has experienced the second largest outbreak of COVID-19 globally, yet there is a paucity of studies analysing contact tracing data in the region which can optimise public health interventions (PHI’s). <h4>Methods</h4> We analysed contact tracing data from Karnataka, India between 9 March and 21 July 2020. We estimated metrics of transmission including the reproduction number (R), overdispersion (k), secondary attack rate (SAR), and serial interval. R and k were jointly estimated using a Bayesian Markov Chain Monte Carlo approach. We studied determinants of risk of further transmission and risk of being symptomatic using Poisson regression models. <h4>Findings</h4> Up to 21 July 2020, we found 111 index cases that crossed the super-spreading threshold of ≥8 secondary cases. Among 956 confirmed traced cases, 8.7% of index cases had 14.4% of contacts but caused 80% of all secondary cases. Among 16715 contacts, overall SAR was 3.6% [95% CI, 3.4–3.9] and symptomatic cases were more infectious than asymptomatic cases (SAR 7.7% vs 2.0%; aRR 3.63 [3.04–4.34]). As compared to infectors aged 19–44 years, children were less infectious (aRR 0.21 [0.07–0.66] for 0–5 years and 0.47 [0.32–0.68] for 6–18 years). Infectors who were confirmed ≥4 days after symptom onset were associated with higher infectiousness (aRR 3.01 [2.11–4.31]). As compared to asymptomatic cases, symptomatic cases were 8.16 [3.29–20.24] times more likely to cause symptomatic infection in their secondary cases. Serial interval had a mean of 5.4 [4.4–6.4] days, and case fatality rate was 2.5% [2.4–2.7] which increased with age. <h4>Conclusion</h4> We found significant heterogeneity in the individual-level transmissibility of SARS-CoV-2 which could not be explained by the degree of heterogeneity in the underlying number of contacts. To strengthen contact tracing in over-dispersed outbreaks, testing and tracing delays should be minimised and retrospective contact tracing should be implemented. Targeted measures to reduce potential superspreading events should be implemented. Interventions aimed at children might have a relatively small impact on reducing transmission owing to their low symptomaticity and infectivity. We propose that symptomatic cases could cause a snowballing effect on clinical severity and infectiousness across transmission generations; further studies are needed to confirm this finding. |
| first_indexed | 2024-04-14T04:48:59Z |
| format | Article |
| id | doaj.art-27656ce6a93044d48bdbd7bf3f9a14d7 |
| institution | Directory Open Access Journal |
| issn | 1932-6203 |
| language | English |
| last_indexed | 2024-04-14T04:48:59Z |
| publishDate | 2022-01-01 |
| publisher | Public Library of Science (PLoS) |
| record_format | Article |
| series | PLoS ONE |
| spelling | doaj.art-27656ce6a93044d48bdbd7bf3f9a14d72022-12-22T02:11:21ZengPublic Library of Science (PLoS)PLoS ONE1932-62032022-01-01177Contact tracing of COVID-19 in Karnataka, India: Superspreading and determinants of infectiousness and symptomatic infectionMohak GuptaGiridara G. ParameswaranManraj S. SraRishika MohantaDevarsh PatelAmulya GuptaBhavik BansalVardhmaan JainArchisman MazumderMehak AroraNishant AggarwalTarun BhatnagarJawaid AkhtarPankaj PandeyVasanthapuram RaviGiridhara R. Babu<h4>Background</h4> India has experienced the second largest outbreak of COVID-19 globally, yet there is a paucity of studies analysing contact tracing data in the region which can optimise public health interventions (PHI’s). <h4>Methods</h4> We analysed contact tracing data from Karnataka, India between 9 March and 21 July 2020. We estimated metrics of transmission including the reproduction number (R), overdispersion (k), secondary attack rate (SAR), and serial interval. R and k were jointly estimated using a Bayesian Markov Chain Monte Carlo approach. We studied determinants of risk of further transmission and risk of being symptomatic using Poisson regression models. <h4>Findings</h4> Up to 21 July 2020, we found 111 index cases that crossed the super-spreading threshold of ≥8 secondary cases. Among 956 confirmed traced cases, 8.7% of index cases had 14.4% of contacts but caused 80% of all secondary cases. Among 16715 contacts, overall SAR was 3.6% [95% CI, 3.4–3.9] and symptomatic cases were more infectious than asymptomatic cases (SAR 7.7% vs 2.0%; aRR 3.63 [3.04–4.34]). As compared to infectors aged 19–44 years, children were less infectious (aRR 0.21 [0.07–0.66] for 0–5 years and 0.47 [0.32–0.68] for 6–18 years). Infectors who were confirmed ≥4 days after symptom onset were associated with higher infectiousness (aRR 3.01 [2.11–4.31]). As compared to asymptomatic cases, symptomatic cases were 8.16 [3.29–20.24] times more likely to cause symptomatic infection in their secondary cases. Serial interval had a mean of 5.4 [4.4–6.4] days, and case fatality rate was 2.5% [2.4–2.7] which increased with age. <h4>Conclusion</h4> We found significant heterogeneity in the individual-level transmissibility of SARS-CoV-2 which could not be explained by the degree of heterogeneity in the underlying number of contacts. To strengthen contact tracing in over-dispersed outbreaks, testing and tracing delays should be minimised and retrospective contact tracing should be implemented. Targeted measures to reduce potential superspreading events should be implemented. Interventions aimed at children might have a relatively small impact on reducing transmission owing to their low symptomaticity and infectivity. We propose that symptomatic cases could cause a snowballing effect on clinical severity and infectiousness across transmission generations; further studies are needed to confirm this finding.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9273085/?tool=EBI |
| spellingShingle | Mohak Gupta Giridara G. Parameswaran Manraj S. Sra Rishika Mohanta Devarsh Patel Amulya Gupta Bhavik Bansal Vardhmaan Jain Archisman Mazumder Mehak Arora Nishant Aggarwal Tarun Bhatnagar Jawaid Akhtar Pankaj Pandey Vasanthapuram Ravi Giridhara R. Babu Contact tracing of COVID-19 in Karnataka, India: Superspreading and determinants of infectiousness and symptomatic infection PLoS ONE |
| title | Contact tracing of COVID-19 in Karnataka, India: Superspreading and determinants of infectiousness and symptomatic infection |
| title_full | Contact tracing of COVID-19 in Karnataka, India: Superspreading and determinants of infectiousness and symptomatic infection |
| title_fullStr | Contact tracing of COVID-19 in Karnataka, India: Superspreading and determinants of infectiousness and symptomatic infection |
| title_full_unstemmed | Contact tracing of COVID-19 in Karnataka, India: Superspreading and determinants of infectiousness and symptomatic infection |
| title_short | Contact tracing of COVID-19 in Karnataka, India: Superspreading and determinants of infectiousness and symptomatic infection |
| title_sort | contact tracing of covid 19 in karnataka india superspreading and determinants of infectiousness and symptomatic infection |
| url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9273085/?tool=EBI |
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