Epidemiology of Coronavirus Disease 2019 during the Second and Third Wave in Chennai, India: An Analysis of the Coronavirus Disease 2019 Surveillance System, February 2021-February 2022.

INTRODUCTION: Analysis of the coronavirus disease 2019 (COVID-19) surveillance system in the first wave indicated that the data-driven approach helped in resource allocation and public health interventions. OBJECTIVES: We described the epidemiology of COVID-19 cases in Chennai, Tamil Nadu, India, from February 2021 to February 2022. MATERIALS AND METHODS: We analyzed the COVID-19 surveillance data from Chennai City, Tamil Nadu, India's Greater Chennai Corporation. We described the deidentified line list of COVID-19 cases and deaths by months, zones, age, and gender. We estimated the incidence of COVID-19 cases per million population, test positivity rate (TPR), and case fatality ratio (CFR). RESULTS: Of the 434,040 cases reported in Chennai from February 1, 2021, to February 28, 2022, 53% were male. The incidence per million peaked in May 2021 (19,210) and January 2022 (15,881). Age groups more than 60 years reported maximum incidence. Southern region zones reported higher incidence. Overall TPR was 5.8%, peaked in May 2021 (17.5%) and January 2022 (15.1%). Over half of the 4929 reported deaths were in May 2021 (56%). Almost half of the deaths were 61-80 years (52%), followed by 41-60 years (26%). Overall CFR was 1%, which peaked in June 2021 (4%). CONCLUSION: We conclude that Chennai city experienced a surge in COVID-19 due to delta and omicron variants. Understanding descriptive epidemiology is vital for planning the public health response, resource allocation, vaccination policies, and risk communication to the community.

Face mask use in the city of Chennai, India: Results from three serial cross-sectional surveys, 2021.

INTRODUCTION: The Government of Tamil Nadu, India, mandated wearing face masks in public places to combat the COVID-19 pandemic. We established face mask surveillance and estimated the prevalence of appropriate mask use (covering the nose, mouth, and chin) in the slums and non-slums of Chennai at different time points in 2021. METHODS: We conducted three serial cross-sectional surveys in the outdoors and indoors of Chennai in March, July, and October 2021. We observed the mask wearing among 3200 individuals in the outdoors and 1280 in the indoors. We divided the outdoor and indoor locations into slums and non-slums. In October 2021, we also surveyed 150 individuals from each of the 11 shopping malls in the city. We calculated the proportions and 95% confidence interval (95%CI) for the appropriate mask use in the outdoor, indoor, and malls by age, gender, region, and setting (slum and non-slum). RESULTS: We observed 3200 individuals in the outdoor and 1280 individuals in the indoor setting, each from a slum and non-slum, during the three rounds of the study. In outdoor and indoors, males comprised three-fourths and middle-aged individuals were half the study population. Mask compliance changed significantly with time (p-value <0.001). Males consistently demonstrated better compliance in all rounds. The south region had the highest mask compliance in slums indoors and outdoors in rounds 4 and 5. Young adults had the highest mask compliance in both outdoor slums and non-slums in all rounds. Overall mask compliance in shopping malls was 57% (95% CI: 48-65). CONCLUSION: The mask compliance in Chennai outdoors during the COVID-19 pandemic was less than 50%, with variations across time points by gender, age groups, and geographical locations. We must develop more effective communication strategies for older age groups and crowded indoor settings.

Rapid assessment of coverage of doxycycline/azithromycin chemoprophylaxis against leptospirosis following floods, Kozhikode district, Kerala, 2018.

BACKGROUND: We estimated coverage of doxycycline chemoprophylaxis (200 mg once weekly) following floods in Kerala, India. METHODS: A cross-sectional survey was conducted to gather data on exposure to flood or stagnant water and receipt and consumption of chemoprophylaxis. RESULTS: Of 1573 individuals interviewed, 152 (10%) were exposed to flood water. Among these, 119 (78%) were eligible for chemoprophylaxis. Of those eligible, 58 (38.2% [95% confidence interval 30.8 to 46.1]) reported consuming the prescribed chemoprophylaxis. CONCLUSIONS: Despite the availability of chemoprophylaxis, consumption was less than ideal. We recommend targeted interventions to improve chemoprophylaxis coverage and public awareness campaigns to enhance its consumption among the affected population.

Implementation of a Triage Protocol Outside the Hospital Setting for Timely Referral During the COVID-19 Second Wave in Chennai, India.

India experienced a surge in COVID-19 cases during the second wave in the period of April-June 2021. A rapid rise in cases posed challenges to triaging patients in hospital settings. Chennai, the fourth largest metropolitan city in India with an 8 million population, reported 7564 COVID-19 cases on May 12, 2021, nearly 3 times higher than the number of cases in the peak of COVID-19 in 2020. A sudden surge of cases overwhelmed the health system. We had established standalone triage centers outside the hospitals in the first wave, which catered to up to 2500 patients per day. In addition, we implemented a home-based triage protocol from May 26, 2021, to evaluate patients with COVID-19 who were aged ≤45 years without comorbidities. Among the 27,816 reported cases between May 26 and June 24, 2021, a total of 16,022 (57.6%) were aged ≤45 years without comorbidities. The field teams triaged 15,334 (55.1%), and 10,917 (39.2%) patients were evaluated at triage centers. Among 27,816 cases, 19,219 (69.1%) were advised to self-isolate at home, 3290 (11.8%) were admitted to COVID-19 care centers, and 1714 (6.2%) were admitted to hospitals. Only 3513 (12.7%) patients opted for the facility of their choice. We implemented a scalable triage strategy covering nearly 90% of the patients in a large metropolitan city during the COVID-19 surge. The process enabled early referral of high-risk patients and ensured evidence-informed treatment. We believe that the out-of-hospital triage strategy can be rapidly implemented in low-resource settings.

Knowledge, attitude, and practice towards face mask use among residents of Greater Chennai Corporation, India, March 2021.

Background: Wearing a mask is one of the simplest ways to reduce the spread of COVID-19. Studies reported poor mask compliance in Greater Chennai Corporation, India. Hence, we described the knowledge, attitude, and practice regarding mask use among adults (≥18 years) in Greater Chennai Corporation, Tamil Nadu, India. Methods: We conducted a cross-sectional survey among residents of Greater Chennai Corporation in March 2021. We estimated the sample size to be 203 per strata (slum and non-slum). We used a simple random sampling technique to select 20 locations using a digital map in the slum and non-slum areas. After reaching the location chosen, we selected 10 consecutive households and one adult (≥18 years of age) from each household. We used a validated, semi-structured questionnaire for collecting data regarding knowledge, attitudes, and practices for mask use. We estimated proportions and 95% CI for key variables and compared the variables between slums and non-slums. Results: Of 430 participants included in the study, 51.4% were males. The mean (S.D.) age of the participants is 41.1 (14.6) years. The majority (86.7%) of the participants felt that wearing a mask helped in reducing the spread of coronavirus and the knowledge differed (p-value < 0.05) between the slum (81.4%) and non-slum (92.3%). Nearly half (46.5%) of the participants did not like being forced to wear the mask. About 63.9% of the participants reported the practice of mask use while going out which was similar across slums and non-slums. Conclusion: Although the knowledge regarding mask use was good among the public, the attitude was unfavorable. We suggest continuous reinforcement by spreading awareness and educating the community on the appropriate use of the mask.

Case report: An outbreak of viral conjunctivitis among the students and staff of visually impaired school, Tamil Nadu, India, 2020.

Introduction: On February 2, 2020, the head of a visually impaired school notified similar eye symptoms among the students. We investigated the cluster to confirm the diagnosis, identify potential exposures, and propose recommendations. Methodology: We defined a case as redness/watering/discharge from any eye among the students and staff, January-February 2020. We actively searched for the cases and calculated attack rates. We drew epicurve by date of symptoms onset. We conducted a retrospective cohort study of students and staff. We collected data on potential exposures and calculated Risk Ratio (RR), 95% Confidence Interval (95%CI), and Population Attributable Risk (PAR). We sent a conjunctival swab of the three cases for microbiological analysis. Results: We diagnosed the cases as acute conjunctivitis and identified 39 (76%) cases among 51 individuals. All the 39 cases reported watering and redness; 28 (72%) and 12 (31%) reported eye pain and discharge, respectively. The median age of the case was 11 years (range: 6-48 years). The attack rate didn't differ significantly between males [77% (20/26)] and females [76% (19/25), p = 0.9]. The attack rate was higher among the students [86%, (38/44)] than staffs [14%, (1/7), p = <0.01]. Contact with a case [RR = 2.5, 95%CI = 1.3-4.8, PAR = 51%] and staying inside campus [RR = 6.0, 95%CI = 1.0-37.3, PAR = 81%] were associated with the acute conjunctivitis outbreak. All the three conjunctival swabs were negative for bacterial growth. Conclusion: Close contact with the case and staying inside the campus led to the outbreak of acute conjunctivitis among the students and staff of the visually impaired school.

Sudden deaths due to accidental leakage of Lindane from a storage tank in a village, Sitapur, Uttar Pradesh, India, 2020: A field epidemiological investigation.

Background: Chemical leakages cause devastating health effects on humans. On 6 February 2020, seven deaths were reported following a hazardous chemical leakage in a village in Uttar Pradesh, India. We investigated the event to identify the cause and propose recommendations. Methods: We defined a case as sudden onset of breathlessness, headache, or death in the village, 6-7 February 2020. We conducted a house-to-house case search and calculated attack rate (AR) and case-fatality rate (CFR) by age and gender. We conducted an environmental investigation at the leakage site and sent the chemicals for forensic analysis. We obtained the cause of death through autopsy reports. Results: Out of 2,942 residents, we identified 23 cases (AR = 8/1,000) and seven deaths (CFR = 30%). The median age of the case was 42 years (range, 2-64 years). The AR was higher among males (14/1,000 [19/1,402]). All the 23 case-patients who were sleeping at the chemical leakage site or visited to witness the event developed symptoms, and all seven cases who were sleeping within 150 meters of the leakage site died. The environmental investigation revealed leakage of hazardous substances from the storage tank. Toxicology analysis confirmed the leaked chemical as Lindane (gamma-hexachlorocyclohexane), and autopsy reports confirmed the cause of death as asphyxia. Conclusions: Asphyxia following the leakage of Lindane from the storage tank possibly led to sudden deaths. We recommend using leak-proof tanks to ensure safe storage and disposal, law enforcement, and regulations to prevent people from staying close to chemical storage sites.

SARS-CoV-2 cluster among security guards, Chennai, Tamil Nadu, India, June-July 2020.

Congregate work settings are at increased risk for SARS-CoV-2 transmission and predispose to super spreader events. We investigated a COVID-19 outbreak among security guards to identify the risk factors and propose recommendations. We defined a COVID-19 case as a laboratory-confirmed reverse transcription polymerase chain reaction-positive case. We traced the contacts actively and described the cases by time, place, and person. We conducted a case-control study and collected data on potential exposures. We identified 20 (27%) COVID-19 cases among 75 security guards. Among the cases, 17 (85%) were male and 12 (60%) were symptomatic. We recruited all the 20 COVID-19-confirmed cases and 55 COVID-19-negative controls for the case-control study. SARS-CoV-2 infection was higher among those had high-risk exposure (60%, [12/20]) than who did not (16%, [9/55], adjusted odds ratio = 5.9, 95% confidence interval = 1.6-22.1). Having had high-risk exposure with COVID-19 cases led to COVID-19 outbreak among the security guards. We recommended avoiding the activities predisposed to high-risk exposure.

Do unmanned aerial vehicles reduce the duration and costs in transporting sputum samples? A feasibility study conducted in Himachal Pradesh, India.

BACKGROUND: The feasibility of and advantages of using an unmanned aerial vehicle (UAV) for sputum transportation for TB in Chamba, Himachal Pradesh, India, were evaluated. METHODS: We conducted a non-randomized interventional study and compared the advantages of sputum transport between UAVs and motorbikes (conventional). RESULTS: We completed 151 transportations. Transportation by UAV (7.1±0.8 min) was faster than by motorbike (22.7±4.6 min, p<0.001). Motorbikes covered a greater distance (12.09±1.6 km) than UAVs (2.89±0.35 km, p<0.001). The recurrent cost per transport using an UAV (US${\$}$0.68) was less than by motorbike (US${\$}$1.4). All 26 stakeholders agreed that UAVs would reduce the turnaround time for diagnosis of drug-resistant TB. CONCLUSIONS: Sputum transportation by UAVs was feasible, cheaper and an efficacious potential alternative to conventional modes of transportation.

Epidemiology of COVID-19 and effect of public health interventions, Chennai, India, March-October 2020: an analysis of COVID-19 surveillance system.

OBJECTIVES: To describe the public health strategies and their effect in controlling the COVID-19 pandemic from March to October 2020 in Chennai, India. SETTING: Chennai, a densely populated metropolitan city in Southern India, was one of the five cities which contributed to more than half of the COVID-19 cases in India from March to May 2020. A comprehensive community-centric public health strategy was implemented for controlling COVID-19, including surveillance, testing, contact tracing, isolation and quarantine. In addition, there were different levels of restrictions between March and October 2020. PARTICIPANTS: We collected the deidentified line list of all the 192 450 COVID-19 cases reported from 17 March to 31 October 2020 in Chennai and their contacts for the analysis. We defined a COVID-19 case based on the real-time reverse transcriptase-PCR (RT-PCR) positive test conducted in one of the government-approved labs. OUTCOME MEASURES: The primary outcomes of interest were incidence of COVID-19 per million population, case fatality ratio (CFR), deaths per million, and the effective reproduction number (Rt). We also analysed the surveillance, testing, contact tracing and isolation indicators. RESULTS: Of the 192 450 RT-PCR confirmed COVID-19 cases reported in Chennai from 17 March to 31 October 2020, 114 889 (60%) were males. The highest incidence was 41 064 per million population among those 61-80 years. The incidence peaked during June 2020 at 5239 per million and declined to 3627 per million in October 2020. The city reported 3543 deaths, with a case fatality ratio of 1.8%. In March, Rt was 4.2, dropped below one in July and remained so until October, even with the relaxation of restrictions. CONCLUSION: The combination of public health strategies might have contributed to controlling the COVID-19 epidemic in a large, densely populated city in India. We recommend continuing the test-trace-isolate strategy and appropriate restrictions to prevent resurgence.

Secondary attack rate of COVID-19 among contacts and risk factors, Tamil Nadu, March-May 2020: a retrospective cohort study.

OBJECTIVE: To describe the characteristics of contacts of patients with COVID-19 case in terms of time, place and person, to calculate the secondary attack rate (SAR) and factors associated with COVID-19 infection among contacts. DESIGN: A retrospective cohort study SETTING AND PARTICIPANTS: Contacts of cases identified by the health department from 14 March 2020to 30 May 2020, in 9 of 38 administrative districts of Tamil Nadu. Significant proportion of cases attended a religious congregation. OUTCOME MEASURE: Attack rate among the contacts and factors associated with COVID-19 positivity. RESULTS: We listed 15 702 contacts of 931 primary cases. Of the contacts, 89% (n: 14 002) were tested for COVID-19. The overall SAR was 4% (599/14 002), with higher among the household contacts (13%) than the community contacts (1%). SAR among the contacts of primary cases with congregation exposure were 5 times higher than the contacts of non-congregation primary cases (10% vs 2%). Being a household contact of a primary case with congregation exposure had a fourfold increased risk of getting COVID-19 (relative risk (RR): 16.4; 95% CI: 13 to 20) than contact of primary case without congregation exposure. Among the symptomatic primary cases, household contacts of congregation primaries had higher RR than household contacts of other cases ((RR: 25.3; 95% CI: 10.2 to 63) vs (RR: 14.6; 95% CI: 5.7 to 37.7)). Among asymptomatic primary case, RR was increased among household contacts (RR: 16.5; 95% CI: 13.2 to 20.7) of congregation primaries compared with others. CONCLUSION: Our study showed an increase in disease transmission among household contacts than community contacts. Also, symptomatic primary cases and primary cases with exposure to the congregation had more secondary cases than others.

Surveillance for face mask compliance, Chennai, Tamil Nadu, India, October-December, 2020.

PURPOSE: Government of Tamil Nadu, India, mandated the face mask wearing in public places as one of the mitigation measures of COVID-19. We established a surveillance system for monitoring the face mask usage. This study aimed to estimate the proportion of the population who wear face masks appropriately (covering nose, mouth, and chin) in the slums and non-slums of Chennai at different time points. METHODS: We conducted cross-sectional surveys among the residents of Chennai at two-time points of October and December 2020. The sample size for outdoor mask compliance for the first and second rounds of the survey was 1800 and 1600, respectively, for each of the two subgroups-slums and non-slums. In the second round, we included 640 individuals each in the slums and non-slums indoor public places and 1650 individuals in eleven shopping malls. We calculated the proportions and 95% confidence interval (95%CI) for the mask compliance outdoors and indoors by age, gender, region, and setting (slum and non-slum). RESULTS: We observed 3600 and 3200 individuals in the first and second surveys, respectively, for outdoor mask compliance. In both rounds, the prevalence of appropriate mask use outdoors was significantly lower in the slums (28%-29%) than non-slum areas (36%-35%) of Chennai (p<0.01). Outdoor mask compliance was similar within slum and non-slum subgroups across the two surveys. Lack of mask use was higher in the non-slums in the second round (50%) than in the first round of the survey (43%) (p<0.05). In the indoor settings in the 2nd survey, 10%-11% among 1280 individuals wore masks appropriately. Of the 1650 observed in the malls, 947 (57%) wore masks appropriately. CONCLUSION: Nearly one-third of residents of Chennai, India, correctly wore masks in public places. We recommend periodic surveys, enforcement of mask compliance in public places, and mass media campaigns to promote appropriate mask use.

Secular trends of grossly underreported snakebite burden in India, 2009-2018: analysis of data from India's National Health Profile.

BACKGROUND: India's National Health Profile (NHP) documents snakebite cases and deaths based on hospital-based reports, hence underrepresenting the actual burden. We describe secular trends of NHP data using population denominators for 2009-2018. METHODS: We abstracted the data on snakebite cases and deaths and calculated incidence and case fatality rate (CFR) by gender and by states using population denominators. We estimated the change in incidence and CFR over time by using a Poisson regression model. We computed the incidence rate ratio (IRR) and 95% confidence interval (CI) using Stata 14.0. RESULTS: The incidence of snakebites ranged from 89 to 141 per million population and without any specific pattern during 2009-2018 as per NHP reports. The incidence increased by 3% per year (IRR 1.03 [95% CI 0.99 to 1.07]). The incidence was higher among males (range 97-163) than females (range 71-115) and there was no difference in trends by gender (IRR 1.07 [95% CI 0.37 to 3.12]). The CFR was 5-13 deaths per 1000 cases, with an annual decline of 12% (IRR 0.88 [95% CI 0.85 to 0.92]). The CFR did not differ by gender (male 5-12, female 6-13; IRR 0.48 [95% CI 0.20 to 1.17]). CONCLUSION: India's NHP snakebite data, representing an underestimate of the actual burden, suggests no specific secular trend and points to areas documenting consistent and significant burden.

Outbreak of ceftriaxone-resistant Salmonella enterica serotype Typhi-Tiruchirappalli, Tamil Nadu, India, June 2018.

Objectives: In May 2018, a laboratory network for antimicrobial resistance (AMR) surveillance in Tamil Nadu, India, detected a cluster of Salmonella enterica serotype Typhi (S. Typhi) isolates resistant to ceftriaxone. We investigated to describe the epidemiology and identify risk factors for the outbreak. Methods: We conducted unmatched case-control studies. We defined a case as illness (fever with abdominal pain, diarrhea or vomiting) in a person with blood culture-confirmed ceftriaxone-resistant S. Typhi isolated between January 1 and July 4, 2018 in Tiruchirappalli, Tamil Nadu. We interviewed cases using a semi-structured questionnaire to identify common exposures to food, water and places visited. Results: We identified 7 cases (5 men) during March 25-June 8, 2018, median age 23 years (range: 12-42); all were hospitalized, none died. Eating at Restaurant A (odds ratio [OR]=22) and chicken gravy (OR=16) was associated with illness. Of the 10 workers at Restaurant A, stool culture from 8 did not detect S. Typhi; 2 did not consent to provide samples. Five water samples around the restaurant showed low or no residual chlorine content. Conclusions: The investigation highlights the value of AMR surveillance in detecting emerging pathogens and the need for timely investigations, along with strengthening food safety.

Entry and initial spread of COVID-19 in India: Epidemiological analysis of media surveillance data, India, 2020.

BACKGROUND: India reported first laboratory-confirmed case of coronavirus disease 2019 (COVID-19) on 30 January from Kerala. Media surveillance is useful to capture unstructured information about outbreaks. We established media surveillance and described the characteristics of the COVID-19 cases, clusters, deaths by time, place, and person during January-March 2020 in India. METHODS: The media surveillance team of ICMR-National Institute of Epidemiology abstracted data from public domains of India's Central and State health ministries, online news and social media platforms for the period of January 31 to March 26, 2020. We collected data on person (socio-demographics, circumstances of travel/contact, clinical and laboratory), time (date/period of reported exposures; laboratory confirmation and death) and place (location). We drew epidemic curve, described frequencies of cases by age and gender. We described available details for identified clusters. RESULTS: As of March 26, 2020, India reported 694 (Foreigners = 45, 6%) confirmed COVID-19 cases (Attack rate = 0.5 per million population) and 17 deaths (Fatality = 2.5%) from 21 States and 6 Union Territories. The cases were higher among 20-59 years of age (60 of 85) and male gender (65 of 107). Median age at death was 68 years (Range: 38-85 years). We identified 13 clusters with a total of 63 cases and four deaths among the first 200 cases. CONCLUSION: Surveillance of media sources was useful in characterizing the epidemic in the early phase. Hence, media surveillance should be integrated in the routine surveillance systems to map the events specially in context of new disease outbreaks.