key: cord-0983246-9p1zz66z authors: Shah, K.; Desai, N.; Saxena, D.; Mavalankar, D.; Mishra, U.; Patel, G. C. title: Household Secondary Attack Rate in Gandhinagar district of Gujarat state from Western India date: 2020-09-05 journal: nan DOI: 10.1101/2020.09.03.20187336 sha: 026c3fdeab81f1e8b3d2a1e19f319f1beefbcf83 doc_id: 983246 cord_uid: 9p1zz66z Objectives: Current retrospective study aims to evaluate household Secondary Attack Rate (SAR) of COVID-19 in Gandhinagar (rural) district of Gujarat, India. Methods: Line-listing of 486 laboratory-confirmed patients, tested between 28th March to 2nd July was collected, out of them 80 (15% of overall sample) cases were randomly selected. Demographic, clinical and household details of cases were collected through telephonic interview. During interview 28 more patients were identified from the same household and were added accordingly. So, study included 74 unrelated cluster of households with 74 primary cases and 386 close contacts. Results: SAR in household contacts of COVID-19 in Gandhinagar was 8.8%. Out of 108, 8 patients expired (7.4%), where higher mortality was observed in primary cases (9.5%) as compared to secondary cases (3%). Occupational analysis showed that majority of the secondary cases (88%) were not working and hence had higher contact time with patient. No out-of-pocket expenditure occurred in 94% of the patients, in remaining 6% average expenditure of 1,49,633INR (2027 USD) was recorded. Conclusions: Key observations from the study are 1) SAR of 8.8% is relatively low and hence home isolation of the cases can be continued 2) Primary case is more susceptible to fatal outcome as compared to secondary cases 3) Government has covered huge population of the COVID-19 patients under cost protection. However, more robust studies with larger datasets are needed to further validate the findings. On global chart of COVID-19, India stands at 3 rd position with 2.4 million cases and around 47,000 deaths as per the latest reports published on 13 th August, 2020 1 . By far transmission trends showed that containment, contact tracing and surveillance are the effective strategies for limiting the spread of infection 2, 3 . Studies have showed that transmission probabilities are highest among household contacts with greater vulnerability of spouses and elderly 4, 5 . It was also observed that close contacts having comorbid conditions are at higher risk of secondary infection 6, 7 . Recently conducted two systematic reviews studied characteristic features of COVID-19 transmission in household contacts 8, 9 . Both showed that household secondary attack rate (SAR) varies widely among different populations and ranges from 4.6% to 49%. India is a culturally, genetically, environmentally and geographically diverse country with specific disease determinants. Hence population specific understanding of the disease transmission is vital to design country specific guidelines. To the best of our knowledge till date there are only two studies published from India that specifically studied SAR 10, 11 With current retrospective study, we aim to assess household SAR in Gandhinagar district of Gujarat state from Western India with an intend to study prevalence, determinants and cost All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. For the study data set of laboratory confirmed COVID-19 patients from Gandhinagar, rural district was obtained from Government records. The line list consisted of 486 cases who were diagnosed positive between 28 th March to 2 nd July, 2020. For the study 15% of the positive cases (n=80) were randomly selected, through the computerized method of random sequence generation from the provided list. Those 80 cases were from unrelated cluster of 74 households. An interview tool was developed to collect the information regarding demographic, clinical and household details from the cases through telephonic interview. The study was reviewed and approved by Gujarat Government and Institutional Ethics Committee (IEC). Detailed interview of the selected 80 cases resulted into identification of 28 new cases who were either primary or secondary cases of the initially selected patients. So, the overall study included 108 cases from 74 households where 74 were primary and 34 were secondary cases of COVID-19 from 386 close household contacts. Demographic, clinical, household, comorbid conditions and cost of diagnosis and treatment of primary and secondary cases were collected using pre-validated data collection tool (figure 1). Initially the tool was validated in few cases and was modified based upon experience of this validation exercise. The patients were approached for the study through telephonic interview. After obtaining verbal consent the details All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted September 5, 2020. . https://doi.org/10.1101/2020.09.03.20187336 doi: medRxiv preprint were collected from each primary and secondary case. Household contact was defined as contact sharing same residential address. Key findings of the study regarding deaths in primary and secondary cases and household SAR are presented in table 1. The diagrammatic representation of the entire study protocol and important observation are presented in figure 1. One of the significant finding was that we observed 0% drop out rate in the study. Household SAR was calculated as a number of household cases occurring within the 28 days incubation time after exposure to a primary case divided by total susceptible household contacts. Out of 386 household contacts of 74 primary cases, 34 contacts developed secondary infection and hence SAR was 8.8% in the studied population. All the enrolled primary and secondary cases were hospitalized and were confirmed through RT-PCR test. Overall death experienced in primary cases were higher as compared to secondary cases (9.5% vs 3%; p=0.23). As shown in table 2 mean age of primary cases was higher than secondary cases. The secondary cases were predominated by female patients (65%). However, prevalence of comorbid conditions was low in secondary cases as compared to primary cases. Occupational analysis showed that 67.6% of the primary cases were working outside their home and hence possibly caught the infection from sources outside home. More females were infected from the primary cases (64.7%) and majority of the secondary cases were not having any occupation (88.2%) and were involved in household work only. This indicates that the potential source of infection transmission was primary case and not any other source. It also indicates that the contacts developing secondary infection might be spending more time with the primary contact. Primary All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted September 5, 2020. . https://doi.org/10.1101/2020.09.03.20187336 doi: medRxiv preprint cases were further grouped as per the infected secondary cases (table 2). It was found that only 6 primary cases (8.1%) infected 3 or more secondary cases in the household contacts. Majority of the patients (94%) received health care facilities including diagnosis and treatment free of cost in government facilities, however few of them (6%) used private health care facilities and the average cost was 1,49,633 INR (2027 USD) in them. Thus, government has provided great subsidy/ cost protection by providing completely free services. It is reported by various studies that household contacts of COVID-19 patients are at greater risk of developing disease as compared to other contacts, principally due to higher contact time in home 12, 13 . Also, during household contact general preventive measures such as wearing of mask and physical distancing norms are often not followed. In different states of India COVID-19 statistics are relatively different than the other states and so the SAR prevalence and its factors were also expected to be different. Hence estimating SAR in various districts and cities or even wards of city is very important. Current study provided some important insights into transmission of the disease in household contacts in Gandhinagar district of Gujarat State. When compared with ICMR national statistics where Gujarat had SAR of 7.8%, our study showed relatively similar SAR from rural setting (8.8%), however this needs to be interpreted with caution as current study included data from only one districts of Gujarat and may not be a representative data of entire state. One recent global review conducted by same team of researchers summarized that SAR varies widely across countries with lowest reported rate as 4.6% and highest as 49.56%. In the same line ICMR study representing Indian statistics also showed range of 0-11.5%, with a national average of 6% 10 . All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted September 5, 2020. . https://doi.org/10.1101/2020.09.03.20187336 doi: medRxiv preprint 6 Though the study was conducted in only one districts and the more data are needed for generalizability of the findings, it was indicated that mortality in primary cases are comparatively higher than secondary cases. However, it did not reach to a statistically significant level and greater sample size with higher event rate is needed to substantiate this further. Categorization of the case according to occupation showed two key findings: 1) In primary cases the individuals working in service sector constituted more than half of the group indicating possibility of catching the infection outside house 2) Secondary cases were majorly found in contact who are not engaged in any work outside houses and hence are expected to spend greater time with the primary contact. It also indicated that there are higher chances of them getting transmission of virus through primary case only. One important find of the study is that availing of free health care services by the patients. The study reports that majority of the population received diagnosis and treatment services for free of cost and that had significant impact on out-of-pocket expenditure. This also indicates awareness regarding available services and trust in the public health care system. Though the study showed some of the important insights into the characteristic features of secondary infection of COVID-19 in household contacts in specific population of India, the generalizability of the findings needs to be validated in the different populations before recommending any policy decisions. Current study provided 1) SAR data from Gandhinagar rural district of Gujarat and compared it against global and national statistics. 2) critical information regarding greater susceptibility of the primary cases for poorer outcome as compared to secondary cases. 3) Policy implication that in an epidemic, government has provided top quality free services and hence no cost of diagnosis All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted September 5, 2020. . https://doi.org/10.1101/2020.09.03.20187336 doi: medRxiv preprint and treatment incurred to majority of the patients. That has showed drastic reduction in out-ofpocket expenditures and reduced cost burden on patients. However more robust studies with larger sample size are needed to substantiate findings of the current study and identifying epidemiological features of disease transmission. Authors declares that there is no personal or professional conflict of interest pertaining to the study. Authors declares that there is no external funding is involved in the study. All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted September 5, 2020. All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted September 5, 2020. . https://doi.org/10.1101/2020.09.03.20187336 doi: medRxiv preprint 1 1 All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted September 5, 2020. . https://doi.org/10.1101/2020.09.03.20187336 doi: medRxiv preprint Evaluation of the effectiveness of surveillance and containment measures for the first 100 patients with COVID-19 in CMMID COVID-19 Working Group. Effectiveness of isolation, testing, contact tracing and physical distancing on reducing transmission of SARS-CoV-2 in different settings Epidemiological characteristics of 2019 novel coronavirus family clustering in Zhejiang Province The characteristics of household transmission of COVID-19 No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted China Medical Treatment Expert Group for COVID-19. Comorbidity and its impact on 1590 patients with COVID-19 in China: a nationwide analysis Prevalence of comorbidities and their association with mortality in patients with COVID-19: A Systematic Review and Meta-analysis Secondary Attack Rate of COVID-19 in household contacts: Systematic review Household transmission of SARS-CoV-2: a systematic review and meta-analysis of secondary attack rate Laboratory surveillance for SARS-CoV-2 in India: Performance of testing & descriptive epidemiology of detected COVID-19 Epidemiology and transmission dynamics of COVID-19 in two Indian states. medRxiv Epidemiology and transmission of COVID-19 in 391 cases and 1286 of their close contacts in Shenzhen, China: a retrospective cohort study All rights reserved. No reuse allowed without permission.(which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.The copyright holder for this preprint this version posted September 5, 2020. . https://doi.org/10.1101/2020.09.03.20187336 doi: medRxiv preprint