This is an observational, prospective, multi-site study which will be conducted in the community and hospitals at three sites in the country, namely, SAS Delhi, KEMHRC Pune and CMC Vellore to improve understanding of the epidemiology of Acute Respiratory Illnesses (ARI) and Acute Lower Respiratory Infections (ALRI) in under-five children.  

We will use a two-tiered approach to capture the complete spectrum of illness. The community- based surveillance will provide information on  mild to moderate illness while the hospital-based surveillance will provide information on severe disease.

A cohort of 335 newborns within 14 days of birth will be enrolled from the community at each site and be actively followed up for a period of two years. Active weekly contacts will be made for each child under surveillance to identify symptoms of PSBI or ARI from birth up for 24 months. For each episode of ARI or PSBI in a child, daily contact will be established and continued until resolution of the ARI or PSBI episode. Nasopharyngeal (NP) swab will be collected from the child with ARI or PSBI at home or at study clinic within 5 days of symptom onset. In children with pneumonia or ALRI, the collected NP swabs will be sent to the central lab for multiplex rt-PCR assay to test for the viral pathogens. Also, a blood sample (3 mL) will be collected at 4-6 weeks from onset of the episode to ascertain antibody response to the infection.

Blood specimen will be collected from the mother after live child birth within 14 days and from the child in the first year of life at 3, 6 and 9 months (from 1/3 of the cohort at each time point)  and at 24 months age from the entire cohort for serosurvey of RSV and Flu infections.

Hospital-based surveillance will be conducted in the secondary/tertiary healthcare facilities of the three study sites. The aim of the hospital-based surveillance is to assess the burden of illnesses due to viral respiratory pathogens which contribute to SARI/sepsis related hospitalizations in under five children. A cohort of 514 children less than 5 years of age hospitalized with SARI will be enrolled at each site over a period of two years. Nasopharyngeal swab will be collected from the respiratory tract of all participants. To study long-term sequelae of disease, all the children hospitalized with severe ARI will be contacted at 90 days after discharge

To study household transmission patterns, a household sub-study will be conducted in the community cohort. Information on symptoms  of respiratory illness in the preceding and following 2 weeks and weekly NP swabs for 2 consecutive weeks, from household contacts of the index child with pneumonia or ALRI will be collected. All members residing in the household will be considered as household contacts.

The socio-cultural practices in the community related to ARI in children including awareness, practices, treatment seeking behaviour, facilitators, and barriers will be studied.

The outcome of the study is to determine the burden of ARI and ALRI and the relative contribution of the viral causes in ALRI, single vs co-infections, spectrum of illness and seasonal and spatial trends.

The study also aims to determine predictors of severe disease, case fatality and disease outcomes, long-term sequelae among children with ARI and ALRI; along with studying awareness and practices, treatment seeking behaviours and antibiotic use related to ARI and ALRI using mix of qualitative and quantitative methods.