RESULTS
type/subtype
VIRUS, INFLUENZA B, INFLUENZA
The trial enrolled 1015 children in the LAIV group and 507 children in the intra‐nasal placebo group in the first year. The nasal shedding analysis was done on specimens from 104 (10.2%) children from the LAIV group and 48 (9.5%) children from the intranasal placebo group in the first year. In the second year, a total of 967 children were administered LAIV, and 477 children were administered intranasal placebo, as per the initial allocation. Nasal shedding study was done on specimens from 108 (11.2%) children in the LAIV group and the 56 (11.7%) in the intranasal placebo group.Except for one child in the placebo group shedding LAIV‐A(H3N2) on day 4 in the first year, no nasal shedding of vaccine or wild‐type virus was seen in this group in the 2 years of the study. Neither circulating virus nor vaccine virus was detected in 23.1% of LAIV recipients on day 2 and in 52.9% on day 4 of year 1. These proportions were 61.1% on day 2 and 76.9% on day 4 of year 2.Wild‐type influenza viruses were excreted in a comparable proportion on day 2 post‐immunization of both the study years (8.7% in year 1 and 9.3% in year 2). On day 4 post‐immunization, 7.7% were shedding wild viruses in the first year as compared to 1.9% in the second year. Shedding of both vaccine and wild‐type virus by the same person was seen in only three children in year 1. During year 1, 71.2% of LAIV recipients shed any LAIV virus on day 2, which was reduced to 42.3% on day 4. In year 2, LAIV detection was markedly reduced to 29.6% on day 2 and 21.3% on day 4 (Table Nasal shedding of influenza viruses (LAIV and wild) among recipients of LAIV vaccine aged 2–10 years in rural north India, 2015–2016.The shedding of vaccine virus subtypes varied between the 2 days of surveillance in year 1. Specifically, on day 2 post‐vaccination, LAIV‐A(H1N1)pdm09 was detected in 11.5% of the LAIV recipients; this was lower than the number of LAIV recipients found to shed LAIV‐A(H3N2) (41.4%) and LAIV‐B (58.7%). Furthermore, on day 4 post‐vaccination, LAIV‐A(H3N2) and LAIV‐B were detected in 23.1% and 26.0% of LAIV recipients, respectively; however, no LAIV recipients (0.0%) had evidence of LAIV‐A(H1N1)pdm09. Only 7.7% of the LAIV recipients shed all three vaccine viruses nasally, and this was only on day 2 of the first year (Tables Nasal shedding of LAIV virus(es) by type/subtype among recipients of LAIV vaccine aged 2–10 years in rural north India, 2015–2016.Nasal shedding of influenza viruses among recipients of LAIV vaccine aged 2–10 years in rural north India, 2015–2016.As observed during year 1, nasal shedding of LAIV viruses was found to vary by strain in year 2, with A(H1N1)pdm09 detection being the least and influenza B being the most commonly detected. To elaborate, on day 2 post‐immunization, the detection of LAIV‐A(H1N1)pdm09 (3.7%) in LAIV recipients was lower than LAIV‐A(H3N2) (7.4%) and LAIV‐B (24.1%). Notably, only one (1%) LAIV recipient each was found to shed with LAIV‐A(H3N2) with LAIV‐A(H1N1)pdm09 and LAIV‐B, respectively, by day 4 post‐immunization; however, 19.4% of LAIV recipients were shedding LAIV‐B even on day 4 (Tables There were 15 children who had been sampled for shedding on days 2 and 4 for both years 1 and 2 (Table Nasal shedding of influenza viruses among 15 recipients of LAIV vaccine who got sampled during both years (2015 and 2016).