Transmission Dynamics of the COVID-19 Epidemic at the District Level in India: Prospective Observational Study

Saurabh, Suman; Verma, Mahendra Kumar; Gautam, Vaishali; Kumar, Nitesh; Goel, Akhil Dhanesh; Gupta, Manoj Kumar; Bhardwaj, Pankaj; Misra, Sanjeev

doi:10.2196/22678

Cited by 11 publications

(4 citation statements)

References 30 publications

(43 reference statements)

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“…We found one study estimating the serial interval of SARS-CoV-2 from contact tracing data in India; however, this study assumed the date of sample collection in asymptomatic cases as a proxy for symptom onset which heavily affects the reliability of their estimate [ 44 ]. Although we present reliable estimates of serial interval for COVID-19 for the first time from India, enhanced data sharing enabling real-time estimation to inform policy decisions is recommended to account for the temporal variation of serial interval as observed in China [ 45 ].…”

Section: Discussionmentioning

confidence: 99%

Contact tracing of COVID-19 in Karnataka, India: Superspreading and determinants of infectiousness and symptomatic infection

et al. 2022

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Background 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). Methods 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. Findings 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. Conclusion 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.

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Section: Discussionmentioning

confidence: 99%

Contact tracing of COVID-19 in Karnataka, India: Superspreading and determinants of infectiousness and symptomatic infection

et al. 2022

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“…[31] The serial interval in our study was 7 days, similar to the mean serial interval of 6.3 observed in more than 3000 cases reported in Jodhpur district over a span of 120 days from March to July 2020. [32] The difference in numbers of the incidence, SAR, and the R0 between the first and the second batch of recruits clearly justifies the benefit of employment of good quarantine measures despite claims that quarantine in such demography could perhaps be a waste of resources.…”

Section: Discussionmentioning

confidence: 99%

Incidence and transmission dynamics of Coronavirus Disease 2019 (COVID-19) among fresh recruits in a Training Establishment of Indian Armed Forces: An observational study

Sakre

Kunte²,

Lakhveer

et al. 2021

IJASM

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Introduction: In times of COVID-19, when all institutions remained closed even post lock-down, the Airmen Training School of Indian Air Force proceeded with the recruitment of airmen. The present study intends to explore the incidence and transmission dynamics of COVID-19 among these freshly recruits who were quarantined in barracks with each barrack serving as one cohort. Material and Methods: In an observational study, 2978 male Air Force recruits, between the age group of 18-22 years, in two batches between 1st to 31st July 2020, were followed up in the quarantine period post recruitment. Since the quarantine was unconventional in terms of being in barracks, special and unique precautions such as repeated screening, delegation of specific toilets per billets, three ply mask distributions, Bio-Medical Waste Disposal etc were paid utmost attention. The COVID 19 cases were treated at the in-house isolation facility and the contacts with the symptomatics tested with RT-PCR or RAT before release from quarantine. All individuals were monitored with active surveillance and the data was meticulously maintained with zero attrition. Incidence, Secondary Attack Rate (SAR), demographic characteristics and others aspects of transmission dynamics were analyzed. Results: The incidence and SAR was observed to be 8.1% (71 primary cases) and 15.59% (170 secondary cases). 64.7% of cases were symptomatic with an average of 15 days of hospitalization. The rate positivity of testing with RTPCR or RAT was 11.44%. Severity was more marked in the first batch than the second batch of recruits. The overall R0 was found to be 2.39. Conclusion: The results of the study revealed some interesting characteristics of COVID-19 transmission dynamics. The cumulative incidence was found to be higher than national average. The variations between the recruits from different part of the country and the two batches could be attributed to the travel distance and mode of conveyance. The study also validates the mild nature of the infection in young adults. Fair conclusion on the implication of good quarantine and isolation measures and regular surveillance for symptoms for early diagnosis has also been compellingly indicated from these observations.

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“…We found one study estimating the serial interval of SARS-CoV-2 from contact tracing data in India; however, this study assumed the date of sample collection in asymptomatic cases as a proxy for symptom onset which heavily affects the reliability of their estimate. (43) Although we present reliable estimates of serial interval for COVID-19 for the first time from India, enhanced data sharing enabling real-time estimation to inform policy decisions is recommended to account for the temporal variation of serial interval as observed in China. (44) Given that the reproduction number is sensitive to the value of serial interval used for its estimation, it is prudent to select the serial interval distribution that fits best in context of the location and time phase of the epidemic.…”

Section: Discussionmentioning

confidence: 99%

Contact Tracing of COVID-19 in Karnataka, India: Superspreading and Determinants of Infectiousness and Symptomaticity

Gupta

Parameswaran

Singh

et al. 2020

Preprint

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Brief AbstractWe analysed SARS-CoV-2 surveillance and contact tracing data from Karnataka, India up to 21 July 2020. We estimated metrics of infectiousness and the tendency for superspreading (overdispersion), and evaluated potential determinants of infectiousness and symptomaticity in COVID-19 cases. Among 956 cases confirmed to be forward-traced, 8.7% of index cases had 14.4% of contacts but caused 80% of all secondary cases, suggesting significant heterogeneity in individual-level transmissibility of SARS-CoV-2 which could not be explained by the degree of heterogeneity in underlying number of contacts. Secondary attack rate was 3.6% among 16715 close contacts. Transmission was higher when index case was aged >18 years, or was symptomatic (adjusted risk ratio, aRR 3.63), or was lab-confirmed ≥4 days after symptom onset (aRR 3.01). Probability of symptomatic infection increased with age, and symptomatic infectors were 8.16 times more likely to generate symptomatic secondaries. This could potentially cause a snowballing effect on infectiousness and clinical severity across transmission generations; further studies are suggested to confirm this. Mean serial interval was 5.4 days. Adding backward contact tracing and targeting control measures to curb super-spreading may be prudent. Due to low symptomaticity and infectivity, interventions aimed at children might have a relatively small impact on reducing transmission.Structured AbstractBackgroundIndia has experienced the second largest outbreak of COVID-19 globally, yet there is a paucity of studies analysing contact tracing data in the region. Such studies can elucidate essential transmission metrics which can help optimize disease control policies.MethodsWe analysed contact tracing data collected under the Integrated Disease Surveillance Programme from Karnataka, India between 9 March and 21 July 2020. We estimated metrics of disease 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 evaluated the effect of age and other factors on the risk of transmitting the infection, probability of asymptomatic infection, and mortality due to COVID-19.FindingsUp to 21 July, we found 111 index cases that crossed the super-spreading threshold of ≥8 secondary cases. R and k were most reliably estimated at R 0.75 (95% CI, 0.62-0.91) and k 0.12 (0.11-0.15) for confirmed traced cases (n=956); and R 0.91 (0.72-1.15) and k 0.22 (0.17-0.27) from the three largest clusters (n=394). 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% (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]). Probability of symptomatic infection increased with age, and symptomatic infectors were 8.16 (3.29-20.24) times more likely to generate symptomatic secondaries. Serial interval had a mean of 5.4 (4.4-6.4) days with a Weibull distribution. Overall case fatality rate was 2.5% (2.4-2.7) which increased with age.ConclusionWe 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, retrospective contact tracing should be considered, and contact tracing performance metrics should be utilised. Targeted measures to reduce potential superspreading events should be implemented. Interventions aimed at children might have a relatively small impact on reducing SARS-CoV-2 transmission owing to their low symptomaticity and infectivity. There is some evidence that symptomatic cases produce secondary cases that are more likely to be symptomatic themselves which may potentially cause a snowballing effect on infectiousness and clinical severity across transmission generations; further studies are needed to confirm this finding.FundingGiridhara R Babu is funded by an Intermediate Fellowship by the Wellcome Trust DBT India Alliance (Clinical and Public Health Research Fellowship); grant number: IA/CPHI/14/1/501499.

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Transmission Dynamics of the COVID-19 Epidemic at the District Level in India: Prospective Observational Study

Cited by 11 publications

References 30 publications

Contact tracing of COVID-19 in Karnataka, India: Superspreading and determinants of infectiousness and symptomatic infection

Contact tracing of COVID-19 in Karnataka, India: Superspreading and determinants of infectiousness and symptomatic infection

Incidence and transmission dynamics of Coronavirus Disease 2019 (COVID-19) among fresh recruits in a Training Establishment of Indian Armed Forces: An observational study

Contact Tracing of COVID-19 in Karnataka, India: Superspreading and Determinants of Infectiousness and Symptomaticity

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