(074) Active and Passive Safety Surveillance in Children Receiving Live Attenuated Influenza Vaccine (LAIV), in England During Early Influenza Seasons from 2014/2015 to 2021/2022

Publication Number: 1069

Background:

Background: Live attenuated influenza vaccine (LAIV), nasal spray suspension (Fluenz® Tetra) is recommended for use in children aged 2-17 years vaccinated as part of the seasonal influenza immunisation campaign in the UK. Here, we present results from LAIV safety surveillance studies carried out during 8 influenza seasons from 2014/2015-2021/2022.

Objectives:

Objectives: To assess the frequencies of suspected adverse drug reactions (sADRs) in children receiving LAIV during early influenza seasons in England.

Methods:

Methods: Active surveillance was conducted in 2014/2015. Vaccinees were recruited via the vaccination programme, and vaccinees or their parents/guardians were asked to complete questionnaires at enrolment and 14 days post vaccination. For subsequent 7 seasons (2015/2016-2021/2022), passive enhanced safety surveillance (ESS) was conducted whereby vaccinees or parents/guardians received a Safety Report Card (SRC) at GP practices or schools, to return if children experienced sADRs after vaccination. At participating sites, immunisation teams recorded numbers of SRCs distributed. During COVID-19, more SRCs were distributed to reflect extension of the flu vaccination programme to include secondary school children up to 12 years of age in 2020/2021 and up to 16 years of age in in 2021/2022. Descriptive statistics were performed.

Results:

Results: For active surveillance (2014/2015), in a final cohort of 385 participants, the most frequently reported adverse event was nasal congestion (43.4%). No serious adverse events were reported and no significant change in reactogenicity was detected. For passive ESS (2015/2016-2021/2022), immunisation teams issued 8,753-16,807 SRCs per season. The number of SRCs returned was highest in 2015/2016 (3.7%; approx. half ineligible) with a decline in subsequent seasons (0.6% in 2021/2022). The overall reporting rate (any sADR) varied from 6.8-18.9/1000 SRCs issued across the 7 passive ESS. The most frequent sADR across all 7 seasons was rhinorrhoea. Reporting of serious sADRs remained rare ( < 1 per 1000 SRCs issued).

Conclusions:

Conclusion: LAIV active surveillance in 2014/2015 showed no significant change in reactogenicity or safety signals. For passive ESS (2015/2016-2021/2022), overall the number of sADRs reported remained low. Reported sADRs were typically non-serious expected events with serious sADRs rarely reported. The pattern and frequency of sADRs were comparable across seasons. Despite the limited number of reports received, the passive ESS method has been shown to be a useful extension to routine pharmacovigilance activities and active surveillance in the monitoring of possible sADRs, and has supported the positive benefit-risk balance of LAIV in children.