Efficacy and Safety of Single-Dose Russian-backbone Live Attenuated Influenza Vaccine among Children in Bangladesh

29 Nov, 16

Introduction

The surveillance data in Bangladesh indicates that influenza virus circulates almost throughout the year and frequently leads to febrile illness and lower respiratory tract infections in children. Thus, preventing influenza illness might reduce the morbidity and mortality in children. Live attenuated influenza vaccine (LAIV) provides an attractive option due to its good efficacy and its easy intranasal mode of administration. Several manufacturers are developing reassortant LAIVs as a part of the WHO-sponsored technology transfer program. This initiative might provide influenza vaccines at an affordable price in low-resource countries like Bangladesh

Study Design

Two-site, randomized, double-blind, placebo-controlled, parallel-group clinical trial.

Treatment Strategy

Children were randomly assigned in a 2:1 ratio to receive one intranasal dose of 0.5 ml (half quantity delivered in each nostril) LAIV (2012–13 Northern Hemisphere formulation, manufactured by Serum Institute of India) or placebo between February 27 and April 9, 2013
The vaccine contained A/California/7/2009 (H1N1)-like, A/Victoria/361/2011 (H3N2)-like, and B/Wisconsin/1/2010 (Yamagata lineage)-like reassortants

Follow-up

Post-vaccination, children were monitored through weekly home visits till day 4 to monitor solicited adverse events (AEs), unsolicited AEs, protocol-defined wheezing illness (PDWI), and serious AEs
Children were monitored thereafter weekly at home by trained field workers

Primary Outcome

Symptomatic, laboratory-confirmed influenza illness due to vaccine-matched strains occurring up to December 31, 2013

Secondary Outcomes

Symptomatic, laboratory confirmed influenza virus infection with any influenza virus strain

Safety Outcome

Immediate reactions occurring within 30 minutes of vaccination
Solicited reactions (nasal congestion, runny nose, ear pain, cough, sore throat, headache, fever, tachypnoea, muscle or joint pain, chills, irritability or decreased activity, and vomiting)
Unsolicited AEs occurring up to 7 days after vaccination

Results

Greater proportion of children administered placebo exhibited laboratory-confirmed influenza illness due to vaccine-matched strains vs. the LAIV-treated children (15·8% vs. 6·7%), translating into a vaccine efficacy of 57·5% (Table 1)

Table 1: Incidence of influenza in the study group

As per a strain-specific analysis, the vaccine exhibited an efficacy of 50–60% for the H3N2 and H1N1 strains.
The vaccine was well tolerated, with AEs balanced between the groups.
No immediate reactions were evident in both the study groups
Runny nose, cough and tachypnoea were the most common AEs reported in the 7 days after vaccination
Most of the AEs were of mild intensity and of similar proportion in both the study groups

Conclusion

The single-dose Russian-backbone LAIV with intranasal delivery was effective in preventing symptomatic laboratory-confirmed influenza illness in children from the urban and rural region of Bangladesh
The vaccine also had a good safety profile with AEs almost similar to that seen with placebo
Integration of LAIV programmes in low- and middle-income countries might diminish the burden of influenza illness

Lancet Glob Health. 2016; 4(12): 946-54.