Burden of Typhoid and Paratyphoid Fever in India.

BACKGROUND: In 2017, more than half the cases of typhoid fever worldwide were projected to have occurred in India. In the absence of contemporary population-based data, it is unclear whether declining trends of hospitalization for typhoid in India reflect increased antibiotic treatment or a true reduction in infection. METHODS: From 2017 through 2020, we conducted weekly surveillance for acute febrile illness and measured the incidence of typhoid fever (as confirmed on blood culture) in a prospective cohort of children between the ages of 6 months and 14 years at three urban sites and one rural site in India. At an additional urban site and five rural sites, we combined blood-culture testing of hospitalized patients who had a fever with survey data regarding health care use to estimate incidence in the community. RESULTS: A total of 24,062 children who were enrolled in four cohorts contributed 46,959 child-years of observation. Among these children, 299 culture-confirmed typhoid cases were recorded, with an incidence per 100,000 child-years of 576 to 1173 cases in urban sites and 35 in rural Pune. The estimated incidence of typhoid fever from hospital surveillance ranged from 12 to 1622 cases per 100,000 child-years among children between the ages of 6 months and 14 years and from 108 to 970 cases per 100,000 person-years among those who were 15 years of age or older. Salmonella enterica serovar Paratyphi was isolated from 33 children, for an overall incidence of 68 cases per 100,000 child-years after adjustment for age. CONCLUSIONS: The incidence of typhoid fever in urban India remains high, with generally lower estimates of incidence in most rural areas. (Funded by the Bill and Melinda Gates Foundation; NSSEFI Clinical Trials Registry of India number, CTRI/2017/09/009719; ISRCTN registry number, ISRCTN72938224.).

Molecular and serological evidence of chikungunya virus infection with high case fatality among pediatric population with acute encephalitis syndrome: first report from Eastern Uttar Pradesh, India.

Acute encephalitis syndrome (AES) outbreaks in children of Eastern Uttar Pradesh (E-UP) region of India have been a longstanding public health issue, with a significant case fatality rate of 20-25%. Since past decade, a rise in chikungunya (CHIK) cases has been occurring, which is a reported etiology of AES. However, the burden of chikungunya virus (CHIKV) among pediatric AES (pAES) is unknown from E-UP. We included 238 hospitalized pAES cases. The presence of IgM antibodies for CHIKV, and Dengue virus (DENV) was tested, and RT-PCR was performed for CHIKV and DENV in serologically confirmed CHIKV and DENV pAES cases. Positive samples were sequenced using Sangers sequencing. Further, to check for co-infection, IgM antibodies for other AES etiologies including Japanese encephalitis virus (JEV), Leptospira and Orientia tsutsugamushi (OT) in serum were also investigated. IgM ELISA demonstrated 5.04% (12) positivity for CHIKV. Among CHIKV IgM positive, 3 (25%, 3/12) pAES patients died. CHIKV genome was detected in 3 pAES specimens. Among which, 2 CHIKV cases were also positive for OT DNA. Partially sequenced CHIKV were genotyped as ECSA. The overall finding indicates evidence of CHIKV infection with high case fatality among pAES patients from E-UP. This study advocates constant serological and molecular surveillance of CHIKV in AES endemic regions of India.

Interplay of missed opportunity for vaccination and poor response to the vaccine led to measles outbreak in a slum area of Eastern Mumbai, India.

In the third week of September 2022, an outbreak of measles was reported from a slum in Eastern Mumbai, India. We sought to investigate whether failure to vaccinate or vaccine failure was the cause. We constructed an epidemic curve, drew a spot map, and calculated the attack rate and case-fatality ratio. We calculated vaccine effectiveness (VE) for one and two doses of measles vaccine in an unmatched case-control study and did stratified analysis by sex, availability of vaccination card, and migrant status. We identified 358 cases and four deaths with a 11.3% attack rate and 1.1% case fatality, both being highest among 0-24-month-old boys. The epidemic curve suggested a propagated mode of spread. The VE for two doses was 64% (95% confidence interval (CI): 23-73%) among under-5-year-old children and 70% (95% CI: 28-88%) among 5-15-year-old children. Failure to vaccinate, consequent to the COVID-19 pandemic, and vaccine hesitancy might have led to the accumulation of susceptible children in the community. Additionally, the occurrence of case-patients among vaccinated suggests reduced VE, which needs further investigation into humoral and cell-mediated immunity as well as contributory factors including nutritional status. Outbreak response immunization to complete immunization of missed and dropout children was carried out to control the outbreak.

Neutralizing antibody responses to SARS-CoV-2 Omicron variants: Post six months following two-dose & three-dose vaccination of ChAdOx1 nCoV-19 or BBV152.

BACKGROUND OBJECTIVES: The Omicron sub-lineages are known to have higher infectivity, immune escape and lower virulence. During December 2022 - January 2023 and March - April 2023, India witnessed increased SARS-CoV-2 infections, mostly due to newer Omicron sub-lineages. With this unprecedented rise in cases, we assessed the neutralization potential of individuals vaccinated with ChAdOx1 nCoV (Covishield) and BBV152 (Covaxin) against emerging Omicron sub-lineages. METHODS: Neutralizing antibody responses were measured in the sera collected from individuals six months post-two doses (n=88) of Covishield (n=44) or Covaxin (n=44) and post-three doses (n=102) of Covishield (n=46) or Covaxin (n=56) booster dose against prototype B.1 strain, lineages of Omicron; XBB.1, BQ.1, BA.5.2 and BF.7. RESULTS: The sera of individuals collected six months after the two-dose and the three-dose demonstrated neutralizing activity against all variants. The neutralizing antibody (NAbs) level was highest against the prototype B.1 strain, followed by BA5.2 (5-6 fold lower), BF.7 (11-12 fold lower), BQ.1 (12 fold lower) and XBB.1 (18-22 fold lower). INTERPRETATION CONCLUSIONS: Persistence of NAb responses was comparable in individuals with two- and three-dose groups post six months of vaccination. Among the Omicron sub-variants, XBB.1 showed marked neutralization escape, thus pointing towards an eventual immune escape, which may cause more infections. Further, the correlation of study data with complete clinical profile of the participants along with observations for cell-mediated immunity may provide a clear picture for the sustained protection due to three-dose vaccination as well as hybrid immunity against the newer variants.

Direct benefit transfer for nutritional support of patients with TB in India-analysis of national TB program data of 3.7 million patients, 2018-2022.

BACKGROUND: Patients with TB have additional nutritional requirements and thus additional costs to the household. Ni-kshay Poshan Yojana(NPY) is a Direct Benefit Transfer (DBT) scheme under the National Tuberculosis Elimination Programme(NTEP) in India which offers INR 500 monthly to all notified patients with TB for nutritional support during the period of anti-TB treatment. Five years after its implementation, we conducted the first nationwide evaluation of NPY. METHODS: In our retrospective cohort study using programmatic data of patients notified with TB in nine randomly selected Indian states between 2018 and 2022, we estimated the proportion of patients who received at least one NPY instalment and the median time to receive the first instalment. We determined the factors associated (i) with non-receipt of NPY using a generalised linear model with Poisson family and log link and (ii) with time taken to receive first NPY benefit in 2022 using quantile regression at 50th percentile. RESULTS: Overall, 3,712,551 patients were notified between 2018 and 2022. During this period, the proportion who received at least one NPY instalment had increased from 56.9% to 76.1%. Non-receipt was significantly higher among patients notified by private sector (aRR 2.10;2.08,2.12), reactive for HIV (aRR 1.69;1.64,1.74) and with missing/undetermined diabetic status (aRR 2.02;1.98,2.05). The median(IQR) time to receive the first instalment had reduced from 200(109,331) days in 2018 to 91(51,149) days in 2022. Patients from private sector(106.9;106.3,107.4days), those with HIV-reactive (103.7;101.8,105.7days), DRTB(104.6;102.6,106.7days) and missing/undetermined diabetic status (115.3;114,116.6days) experienced longer delays. CONCLUSIONS: The coverage of NPY among patients with TB had increased and the time to receipt of benefit had halved in the past five years. Three-fourths of the patients received at least one NPY instalment, more than half of whom had waited over three months to receive the first instalment. NTEP has to focus on timely transfer of benefits to enable patients to meet their additional nutritional demands, experience treatment success and avoid catastrophic expenditure.

Why should the men who have sex with men population in India be vigilant for monkeypox infection?

Monkeypox (MPX) is a zoonotic infection caused by the monkeypox virus (MPXV) and is primarily characterized by rash or pox marks and lymph node enlargement. The recent MPX has quickly spread across the globe and is now declared a global public health emergency. Being a contact illness, sexual encounters have been identified as the most common mode of transmission in the 2022 multicountry MPX outbreak. Data suggest that MPX is highly concentrated in men who have sex with men (MSM) networks and among those who had a recent sexual encounter with one or more partners. In India, the estimated MSM population was 569,346 in 2019. An analysis of the sexual partnerships among MSM suggests a potential highly interconnected MSM network in India, increasing the risk of MPX burden. The viewpoint emphasizes the need for community-level awareness and surveillance for the early detection and prevention of MPX infection in India.

India Field Epidemiology Training Program Response to COVID-19 Pandemic, 2020-2021.

The India Field Epidemiology Training Program (FETP) has played a critical role in India's response to the ongoing COVID-19 pandemic. During March 2020-June 2021, a total of 123 FETP officers from across 3 training hubs were deployed in support of India's efforts to combat COVID-19. FETP officers have successfully mitigated the effect of COVID-19 on persons in India by conducting cluster outbreak investigations, performing surveillance system evaluations, and developing infection prevention and control tools and guidelines. This report discusses the successes of select COVID-19 pandemic response activities undertaken by current India FETP officers and proposes a pathway to augmenting India's pandemic preparedness and response efforts through expansion of this network and a strengthened frontline public health workforce.

Restoration of dendritic cell homeostasis and Type I/Type III interferon levels in convalescent COVID-19 individuals.

BACKGROUND: Plasmacytoid and myeloid dendritic cells play a vital role in the protection against viral infections. In COVID-19, there is an impairment of dendritic cell (DC) function and interferon secretion which has been correlated with disease severity. RESULTS: In this study, we described the frequency of DC subsets and the plasma levels of Type I (IFNα, IFNß) and Type III Interferons (IFNλ1), IFNλ2) and IFNλ3) in seven groups of COVID-19 individuals, classified based on days since RT-PCR confirmation of SARS-CoV2 infection. Our data shows that the frequencies of pDC and mDC increase from Days 15-30 to Days 61-90 and plateau thereafter. Similarly, the levels of IFNα, IFNß, IFNλ1, IFNλ2 and IFNλ3 increase from Days 15-30 to Days 61-90 and plateau thereafter. COVID-19 patients with severe disease exhibit diminished frequencies of pDC and mDC and decreased levels of IFNα, IFNß, IFNλ1, IFNλ2 and IFNλ3. Finally, the percentages of DC subsets positively correlated with the levels of Type I and Type III IFNs. CONCLUSION: Thus, our study provides evidence of restoration of homeostatic levels in DC subset frequencies and circulating levels of Type I and Type III IFNs in convalescent COVID-19 individuals.

Clinical profile of patients infected with suspected SARS-CoV-2 Omicron variant of concern, Tamil Nadu, India, December 2021-January 2022.

Background & objectives: COVID-19 cases have been rising rapidly in countries where the SARS-CoV-2 variant of concern (VOC), Omicron (B.1.1.529) has been reported. We conducted a study to describe the epidemiological and clinical characteristics and outcomes of COVID-19 patients with 'S' gene target failure (SGTF, suspected Omicron). Furthermore, their clinical outcomes with COVID-19 patients with non-SGTF (non-Omicron) were also compared. Methods: This study was conducted in Tamil Nadu, India, between December 14, 2021 and January 7, 2022 among patients who underwent reverse transcription-PCR testing for SARS-CoV-2 in four laboratories with facilities for S gene screening. Consecutively selected COVID-19 patients with SGTF were telephonically contacted, seven and 14 days respectively after their date of positive result to collect information on the socio-demographic characteristics, previous history of COVID-19, vaccination status and clinical course of illness along with treatment details. To compare their outcomes with non-SGTF patients, one randomly suspected non-Omicron case for every two suspected Omicron cases from the line-list were selected, matching for the date of sample collection and the testing laboratory. Results: A total of 1175 SGTF COVID-19 patients were enrolled for this study. Almost 6 per cent (n=72) reported a history of previous infection. 141 (13.5%) suspected Omicron cases were non-vaccinated, while 148 (14.2%) and 703 (67.4%) had received valid one and two doses of COVID-19 vaccines, respectively. Predominant symptoms reported included fever (n=508, 43.2%), body pain (n=275, 23.4%), running nose (n=261, 22.2%) and cough (n=249, 21.2%). Five (0.4%) of the 1175 suspected Omicron cases required oxygen supplementation as compared to ten (1.6%) of the 634 suspected non-Omicron cases. No deaths were reported among omicron suspects, whereas there were four deaths among suspected non-Omicron cases. Interpretation & conclusions: Majority of the suspected Omicron cases had a mild course of illness. The overall severity of these cases was less compared to the suspected non-Omicron cases.

Development of the India COVID-19 vaccine tracker.

COVID-19 was declared a pandemic by the World Health Organization (WHO) on March 11, 2020. Since then, efforts were initiated to develop safe and effective vaccines. Till date, 11 vaccines have been included in the WHO's emergency use list. The emergence and spread of variant strains of SARS-CoV-2 has altered the disease transmission dynamics, thus creating a need for continuously monitoring the real-world effectiveness of various vaccines and assessing their overall impact on disease control. To achieve this goal, the Indian Council of Medical Research (ICMR) along with the Ministry of Health and Family Welfare, Government of India, took the lead to develop the India COVID-19 Vaccination Tracker by synergizing three different public health databases: National COVID-19 testing database, CoWIN vaccination database and the COVID-19 India portal. A Vaccine Data Analytics Committee (VDAC) was constituted to advise on various modalities of the proposed tracker. The VDAC reviewed the data related to COVID-19 testing, vaccination and patient outcomes available in the three databases and selected relevant data points for inclusion in the tracker, following which databases were integrated, using common identifiers, wherever feasible. Multiple data filters were applied to retrieve information of all individuals ≥18 yr who died after the acquisition of COVID-19 infection with or without vaccination, irrespective of the time between vaccination and test positivity. Vaccine effectiveness (VE) against the reduction of mortality and hospitalizations was initially assessed. As compared to the hospitalization data, mortality reporting was found to be much better in terms of correctness and completeness. Therefore, hospitalization data were not considered for analysis and presentation in the vaccine tracker. The vaccine tracker thus depicts VE against mortality, calculated by a cohort approach using person-time analysis. Incidence of COVID-19 deaths among one- and two-dose vaccine recipients was compared with that among unvaccinated groups, to estimate the rate ratios (RRs). VE was estimated as 96.6 and 97.5 per cent, with one and two doses of the vaccines, respectively, during the period of reporting. The India COVID-19 Vaccination Tracker was officially launched on September 9, 2021. The high VE against mortality, as demonstrated by the tracker, has helped aid in allaying vaccine hesitancy, augmenting and maintaining the momentum of India's COVID-19 vaccination drive.

"Design and implementation challenges of massive open online course on research methods for Indian medical postgraduates and teachers -descriptive analysis of inaugural cycle".

BACKGROUND: In view of the growing popularity, reach and access for Massive Open Online Courses (MOOCs), India's apex body for medical education, the National Medical Commission (NMC) mandated uniform foundational course on research methods for the medical post graduates (PGs) and faculty members of the medical institutions under NMC as MOOC. This course is a pioneering effort in the field of India's PG medical education. NMC entrusted Indian Council of Medical Research (ICMR)-National Institute of Epidemiology (NIE) to design and offer the MOOC, named as Basic Course in Biomedical Research (BCBR). We describe the experience of designing and that of implementation challenges in the inaugural cycle of the course. METHODS: The course objective was to inculcate the fundamental concepts in research methods covering epidemiology and biostatistics in the form of video lectures, resource materials, discussion forum, assignments, feedback and a final proctored examination. The course was delivered over 16 weeks through MOOCs platform under the Indian Ministry of Education. We reviewed records, documents and faculty notes and described the course conceptualization, development, design and implementation process. We abstracted information from course portal on enrolment profile of the participants, self-reported course feedback (structured and open-ended on format, lectures and quality of contents), examination registration form, scores obtained in the assignments/examination and that of the participant queries. We described quantitative data using descriptive statistics. We presented the thematic analysis of qualitative data from open-ended questions in the feedback system and that of email interactions. RESULTS: The inaugural cycle (September-December 2019) was taken by 24,385 participants. Majority, 15,879 (65%) were from medical background. 13,242 (54%) were medical postgraduates and 2637 (11%) were medical teachers. Among the enrolled, 14,720 (60%) cleared the assignments. A total of 11,392 (47%), 8,205 (62%) medical PGs and 896 (34%) faculty members successfully completed the course. Feedback from 1305 (5%) participants had mean score of 4.5/5 (±0.7) for quality of teaching. We faced challenges in customizing the course for medical participants, unawareness among target group, digital illiteracy and the ongoing pandemic. CONCLUSIONS: During the inaugural cycle of the online Basic Course in Biomedical Research course, nearly half of the enrolled participants successfully completed and received the certificate. India's MOOC for enhancing research capabilities of future medical researchers encountered successes and challenges. Lessons learnt from the inaugural cycle will guide future directions and to address larger issues in terms of sustainability and replication by stakeholders in medical education in India or elsewhere.

Healthcare Utilization Survey in the Hybrid Model of the Surveillance for Enteric Fever in India (SEFI) Study: Processes, Monitoring, Results, and Challenges.

BACKGROUND: Lack of reliable data in India drove the "Surveillance of Enteric Fever in India" (SEFI) concept. Hybrid surveillance, combining facility-based surveillance for the crude incidence, and a community-based healthcare utilization survey (HCUS) to calculate the factor needed to arrive at the adjusted incidence, was used in 6 sites. The HCUS aimed to determine the percentage of utilization of study facilities by the catchment population for hospitalizations due to febrile illness. METHODS: Population proportional to size sampling and systematic random sampling, in 2 stages, were used to survey 5000 households per site. Healthcare utilization was assessed. RESULTS: Febrile illness accounted for 20% of admissions among 137 990 individuals from 30 308 households. Only 9.6%-38.3% of those admitted with febrile illness sought care in the study hospitals. The rate of rural utilization of the private sector for hospitalization was 67.6%. The rate of hospitalization for febrile illness, per 1000 population, ranged from 2.6 in Manali to 9.6 in Anantapur; for 25.8% of the deaths associated with febrile illness, no facility was used before death. CONCLUSIONS: One in 5 hospitalizations were associated with fever. Rural utilization of the private sector for hospitalization due to febrile illness was more than that of the public sector. Healthcare utilization patterns for hospital admissions due to febrile illness varied across sites. A meticulously performed HCUS is pivotal for accurate incidence estimation in a hybrid surveillance. CLINICAL TRIALS REGISTRATION: ISRCTN72938224.

Population-Based Serosurvey for Severe Acute Respiratory Syndrome Coronavirus 2 Transmission, Chennai, India.

We conducted a cross-sectional survey to estimate the seroprevalence of IgG against severe acute respiratory syndrome coronavirus 2 in Chennai, India. Among 12,405 serum samples tested, weighted seroprevalence was 18.4% (95% CI 14.8%-22.6%). These findings indicate most of the population of Chennai is still susceptible to this virus.

Seroprevalence of IgG antibodies against SARS-CoV-2 among the general population and healthcare workers in India, June-July 2021: A population-based cross-sectional study.

BACKGROUND: India began COVID-19 vaccination in January 2021, initially targeting healthcare and frontline workers. The vaccination strategy was expanded in a phased manner and currently covers all individuals aged 18 years and above. India experienced a severe second wave of COVID-19 during March-June 2021. We conducted a fourth nationwide serosurvey to estimate prevalence of SARS-CoV-2 antibodies in the general population aged ≥6 years and healthcare workers (HCWs). METHODS AND FINDINGS: We did a cross-sectional study between 14 June and 6 July 2021 in the same 70 districts across 20 states and 1 union territory where 3 previous rounds of serosurveys were conducted. From each district, 10 clusters (villages in rural areas and wards in urban areas) were selected by the probability proportional to population size method. From each district, a minimum of 400 individuals aged ≥6 years from the general population (40 individuals from each cluster) and 100 HCWs from the district public health facilities were included. The serum samples were tested for the presence of IgG antibodies against S1-RBD and nucleocapsid protein of SARS-CoV-2 using chemiluminescence immunoassay. We estimated the weighted and test-adjusted seroprevalence of IgG antibodies against SARS-CoV-2, along with 95% CIs, based on the presence of antibodies to S1-RBD and/or nucleocapsid protein. Of the 28,975 individuals who participated in the survey, 2,892 (10%) were aged 6-9 years, 5,798 (20%) were aged 10-17 years, and 20,285 (70%) were aged ≥18 years; 15,160 (52.3%) participants were female, and 21,794 (75.2%) resided in rural areas. The weighted and test-adjusted prevalence of IgG antibodies against S1-RBD and/or nucleocapsid protein among the general population aged ≥6 years was 67.6% (95% CI 66.4% to 68.7%). Seroprevalence increased with age (p < 0.001) and was not different in rural and urban areas (p = 0.822). Compared to unvaccinated adults (62.3%, 95% CI 60.9% to 63.7%), seroprevalence was significantly higher among individuals who had received 1 vaccine dose (81.0%, 95% CI 79.6% to 82.3%, p < 0.001) and 2 vaccine doses (89.8%, 95% CI 88.4% to 91.1%, p < 0.001). The seroprevalence of IgG antibodies among 7,252 HCWs was 85.2% (95% CI 83.5% to 86.7%). Important limitations of the study include the survey design, which was aimed to estimate seroprevalence at the national level and not at a sub-national level, and the non-participation of 19% of eligible individuals in the survey. CONCLUSIONS: Nearly two-thirds of individuals aged ≥6 years from the general population and 85% of HCWs had antibodies against SARS-CoV-2 by June-July 2021 in India. As one-third of the population is still seronegative, it is necessary to accelerate the coverage of COVID-19 vaccination among adults and continue adherence to non-pharmaceutical interventions.

Prediction of probability of rubella based on eye outcomes (PORBEO Nomogram)-a cross-sectional sentinel surveillance of 1134 infants.

INTRODUCTION: Rubella is an important infectious, vaccine-preventable etiology of congenital defects. The aim of the study was to develop a prediction nomogram to assess the probability of an infant being at risk for congenital rubella based on demographics and ophthalmological findings. METHODS: This was a cross-sectional sentinel surveillance study conducted at 5 centers spanning pan-India and involved 1134 infants. The diagnosis of rubella was made using standard guidelines. For the construction of the prediction model, laboratory-confirmed cases were grouped as "at-risk" (AR) infants and the discarded cases into "not at risk" (NAR) infants. Univariate analysis (p value cut-off < 0.05) followed by multivariate binary logistic regression model development was performed. RESULTS: The average (median) age of the suspected CRS infants was 3 (IQR 1-6) months, and the average (mean) age of their mothers was 25.8 ± 4.1 years. Out of the total infants, 81 (7.3%) died, 975 (88%) were alive, and 55 (5.0%) were lost to follow-up. The final model showed that the odds of cataract, retinopathy, glaucoma, microcornea, and age of the infant at presentation were 3.1 (2.2-4.3), 4.9(2.3-10.4), 2.7(1.1-5.9), 2.3(1.1-4.7), and 1.1 (1-1.1), respectively, for the AR infant as compared to NAR infant. AUC of final model was 0.68 (95% CI Delong, 0.64-0.72). Bootstrapping for calibration of the model showed satisfactory results. Nomogram, along with a web version, was developed. CONCLUSION: The developed nomogram would have a wide community-based utilization and will help in prioritizing attention to high-risk children, thereby avoiding loss to follow-up.

Investigations of seasonal outbreaks of acute encephalitis syndrome due to Orientia tsutsugamushi in Gorakhpur region, India: A One Health case study.

Gorakhpur division consisting of Gorakhpur and neighboring districts Deoria, Kushinagar and Maharajganj in Uttar Pradesh, India, have been witnessing seasonal outbreaks of acute encephalitis syndrome (AES) among children for the last three decades. Investigations conducted during 2005 identified Japanese encephalitis (JE) virus as an aetiology of AES. With the introduction of JE vaccination and other control strategies, the incidence of JE in the region declined, however, outbreaks of acute febrile illness with neurological manifestations continued to occur. Subsequent investigations identified Orientia tsutsugamushi, as the major aetiology of AES outbreaks in the region. This review details clinical, epidemiological, animal and entomological investigations conducted for AES due to O. tsutsugamushi during 2015 and 2017 in Gorakhpur region. Surveillance of acute febrile illness among children attending peripheral health facilities identified scrub typhus as an important aetiology of febrile illness during monsoon and post-monsoon months. Population-based serosurveys indicated high endemicity of scrub typhus. Entomological studies demonstrated natural infection of O. tsutsugamushi in small animal hosts and vector mites. Children acquired this infection through recent exposure to outdoor environment, while playing, or visiting fields or defecating in open fields. A few of the children with scrub typhus progress to develop CNS manifestations. Hence, early administration of appropriate antibiotics is crucial in preventing progression of AFI due to scrub typhus to AES. The investigations conducted by the multi-disciplinary team helped understand the transmission dynamics of scrub typhus in Gorakhpur division and recommend strategies for its control.

Antibody responses to the BBV152 vaccine in individuals previously infected with SARS-CoV-2: A pilot study.

Background & objectives: Vaccination against SARS-CoV-2 is a recommendation from the World Health Organization as the foremost preference in the current situation to control the COVID-19 pandemic. BBV152 is one of the approved vaccines against SARS-CoV-2 in India. In this study, we determined SARS-CoV-2-specific antibody levels at day 0 (baseline, before vaccination), day 28 ± 2 post-first dose (month 1) and day 56 ± 2 post-first dose (month 2) of BBV152 whole-virion-inactivated SARS-CoV-2 recipients, and compared the antibody responses of individuals with confirmed pre-vaccination SARS-CoV-2 infection to those individuals without prior evidence of infection. Methods: Blood samples were collected from 114 healthcare professionals and frontline workers who received BBV152 vaccine from February to May & June 2021. Prior infection with SARS-CoV-2 was determined at baseline. Serum samples were used to estimate SARS-CoV-2 nucleoprotein-specific IgG [IgG (N)], spike protein-specific IgG [IgG (S)] and neutralizing antibodies (NAb). Results: Participants with previous SARS-CoV-2 infection after a single vaccine dose elicited IgG (N) and IgG (S) antibody levels along with NAb binding inhibition responses levels were similar to infection-naïve vaccinated participants who had taken two doses of vaccine. Interpretation & conclusions: Our preliminary data suggested that a single dose of BBV152-induced humoral immunity in previously infected individuals was equivalent to two doses of the vaccine in infection-naïve individuals. However, these findings need to be confirmed with large sized cohort studies.

Age- & sex-specific infection fatality ratios for COVID-19 estimated from two serially conducted community-based serosurveys, Chennai, India, 2020.

Background & objectives: Infection fatality ratio (IFR) is considered a more robust and reliable indicator than case fatality ratio for severity of SARS-CoV-2 infection. Age- and sex-stratified IFRs are crucial to guide public health response. Infections estimated through representative community-based serosurveys would gauge more accurate IFRs than through modelling studies. We describe age- and sex-stratified IFR for COVID-19 estimated through serosurveys conducted in Chennai, India. Methods: Two community-based serosurveys were conducted among individuals aged ≥10 yr during July and October 2020 in 51 of the 200 wards spread across 15 zones of Chennai. Total number of SARS-CoV-2 infections were estimated by multiplying the total population of the city aged ≥10 yr with the weighted seroprevalence and IFR was calculated by dividing the number of deaths with the estimated number of infections. Results: IFR was 17.3 [95% confidence interval (CI): 14.1-21.6] and 16.6 (95% CI: 13.8-20.2) deaths/10,000 infections during July and October 2020, respectively. Individuals aged 10-19 years had the lowest IFR [first serosurvey (R1): 0.2/10,000, 95% CI: 0.2-0.3 and second serosurvey (R2): 0.2/10,000, 95% CI: 0.1-0.2], and it increased with age and was highest among individuals aged above 60 yr (R1: 140.0/10,000, 95% CI: 107.0-183.8 and R2: 111.2/10,000, 95% CI: 89.2-142.0). Interpretation & conclusions: Our findings suggested that the IFR increased with age and was high among the elderly. Therefore, elderly population need to be prioritized for public health interventions including vaccination, frequent testing in long-term care facilities and old age homes, close clinical monitoring of the infected and promoting strict adherence to non-pharmaceutical interventions.

Spotted Fever Group Rickettsiae among Children with Acute Febrile Illness, in Gorakhpur, India.

Seasonal outbreaks of acute encephalitis syndrome have been occurring in Gorakhpur division in the Indian state of Uttar Pradesh during monsoon and post-monsoon months. Orientia tsutsugamushi was identified as the major aetiology of these outbreaks. Orientia tsutsugamushi was also identified as one of the important aetiology of febrile illness among children attending peripheral health facilities. The present study was undertaken to detect antibodies against spotted fever group rickettsiae (SFGR) and typhus group rickettsiae (TGR) among children with acute febrile illness presenting at peripheral health facilities in Gorakhpur district. Of the 224 blood samples tested, SFGR infection was detected in 13 (6%) patients. None of the samples tested positive for TGR.

Shellfish poisoning outbreaks in Cuddalore District, Tamil Nadu, India.

BACKGROUND: Two suspected shellfish poisoning events were reported in Cuddalore District in Tamil Nadu, India, between January and April 2015. OBJECTIVES: The study was conducted to confirm the outbreaks and to identify the source and risk factors. METHODS: For both outbreaks, a case was defined as a person with nausea, vomiting, or dizziness. Sociodemographic details and symptoms were noted down. Data were also collected in a standard 3-day food frequency questionnaire, along with a collection of clam samples. A case-control study was initiated in the April outbreak. Stool samples were collected from cases, and clam vendors were interviewed. RESULTS: In an outbreak that happened in January, all the twenty people reported to be consumed clams were diagnosed as cases (100% attack rate, 100% exposure rate). In the April outbreak, we identified 199 cases (95% attack rate). In both outbreaks, the clams were identified as genus Meretrix meretrix. The most common reported symptoms were dizziness and vomiting. The clams heated and consumed within 30-60 min. No heavy metals or chemicals were detected in the clams, but assays for testing shellfish toxins were unavailable. All 64 selected cases reported clam consumption (100% exposure rate) as did 11 controls (17% exposure rate). Illness was associated with a history of eating of clams (odds ratio = 314, 95% confidence interval = 39-512). Of the six stool samples tested, all were culture negative for Salmonella, Shigella, and Vibrio cholerae. The water at both sites was contaminated with garbage and sewage. CONCLUSION: Coordinated and timely efforts by a multidisciplinary team of epidemiologists, marine biologists, and food safety officers led to the outbreaks' containment.