ab Vasil'eva 1988a.

Methods	RCT assessing reactogenicity and immunogenicity of bivalent vaccine "RCT of inactivated influenza vaccine; large‐scale study of the effect of multiple immunisations on immunity. Children were randomised in groups for safety evaluation. Children were randomised (in sub‐group) as individuals for immunogenicity evaluation. Vaccination was carried out once, twice, 3 times, 3 times with interval of 2 years, 4 times but sub‐groups only were evaluated for 5 days after inoculation; measuring temperature, local reactions and subjective complaints Data on long‐term consequences, somatic and infectious disease (excluding influenza and ARI) and allergies were collected from all participants over a 6 month period after inoculation. Sub‐groups were monitored for any admissions to hospital during 30 days following immunisation"
Participants	12,643 children aged 11 to 14 years from Rostov‐on‐Don in the former USSR recruited during the period October 1984 to May 1986
Interventions	Bivalent inactivated, chromatographic influenza vaccine A/Philippines/82 (H3N2) and A/Kiev/59/79 (H1N1)
Outcomes	Serological Immunological tests (with determination of concentration of IgA, IgE, and IgM) were carried out on a subgroup. "Allergising effect" of vaccine was determined by measuring IgE by radio‐immunological method and antibodies towards chicken embryos in haemagglutination neutralisation reaction. Effectiveness N/A Safety Increase in temperature within 5 days of inoculation Intoxication and catarrh in nasopharynx within 5 days Hyperaemia within 5 days Infiltration within 5 days Pain at administration site within 5 days Requests for urgent medical attention within 30 days Hospitalisation within 30 days Morbidity due to nosological disease (excluding influenza and ARI) within 30 days, although not entirely clear from text Increase in antibody titre ‐ chicken embryo protein (data not extracted) Increase in antibody titre ‐ parainfluenza (data not extracted)
Funding Source	Unclear
Notes	The authors conclude that multiple immunisations with bivalent vaccine do not have an immunity‐suppressing effect. Unclear rationale for subgroup sampling and sketchy description of methods. Much may have been lost in translation.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Insufficient description
Allocation concealment (selection bias)	High risk	Not used
Blinding (performance bias and detection bias) All outcomes	Unclear risk	No blinding
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	No description
Summary assessments	High risk	Unclear rationale for subgroup sampling and sketchy description of methods