ca Chumakov 1987.

Methods	Prospective cohort study, re‐analysis of data from Bashliaeva 1986, which did not take into account that influenza vaccine is not intended for prophylaxis of other ARIs, which make up about 70% of total and occur repeatedly in children aged 3 to 6 years "Full formation of immunity can only be expected in children 1 month after second dose. So desirable that vaccination should be completed no later than 1 month before beginning of epidemiological rise in cases of viral influenza." Authors claim this condition was not observed in Baslyaeva 86 study causing reduction in children vaccinated twice who had prepared immune status before beginning of influenza outbreak. Claim figures for numbers of children inoculated in Bashlyaeva 86 are wrong, caused by error in calculation and designation of groups. Bashlyaeva 86 did not report that 411 inoculated children were eliminated from the observations for various reasons and should be excluded from the analysis. The authors claim that inoculations began late, when an epidemic situation has already arisen, and numbers of children attending nurseries had dropped by the time the second vaccination was administered (to a comparatively smaller number of children). The authors claim that antigenic activity was incorrectly analysed.
Participants	See Bashliaeva 1986 ‐ 2274 children were inoculated once with the 2 vaccine types, 876 were inoculated twice; 1321 and 573 children were inoculated with placebo, respectively.
Interventions	See Bashliaeva 1986 ‐ 2 types of the vaccine were tested (15 and 16). The vaccines contained 3 strains (A/Brazil/11/78 (H1N1), A/Bangkok/1/79 (H3N2), and B/Singapore/222/79). The total amount of the B haemagglutinin varied: 31.9 μg (type 15) and 29.2 μg (type 16). The vaccines also contained ovalbumin (type 15 was 0.125 μg/mL; type 16 was 0.06 μg/mL). Sterile, apyrogenic, physiological solution was used for placebo. Vaccines or placebo were administered subcutaneously: 2 doses of 0.5 mL, with an interval of 28 to 30 days.
Outcomes	Effectiveness: Cases of ARI and influenza Influenza and ILI. 2 statements assess the impact of influenza: "With the aim of serologically analysing the clinical diagnoses of influenza and acute respiratory illnesses from the children who fell ill during the period of observation, 470 coupled samples of serum were taken (I –in the first days of illness, II‐ 18 to 20 days later)" and "In order to analyse the aetiology of the spread of the virus, 380 children were observed who had contracted influenza or acute respiratory illnesses, both those who had received the vaccine and those who had received placebo. The division of viruses of influenza was determined from swabs taken from the nose and throat area, implanted onto chicken embryos and the subsequent identification of that which had been isolated" Serology There are 2 apparently contradictory statements concerning serology and partly safety assessment: "The reactogenicity and antigenic activity of the vaccine were studied by observing the 305 vaccinated children and the 237 children who had received the placebo in 15 schools. They were assessed according to a series of well known indices, characterising the frequency and intensiveness of the local and general reactions to the vaccination" and "in order to study the antigenic activity of ‘Grippovac SE‐AZH’, 320 samples of serum were taken from the inoculated children before vaccination, 280 samples were taken 21 days after the first injection and 170 samples were taken 21 days after the second injection". The reasons for this apparent attrition are unclear. Safety See above. Other harms data (headaches, etc.) are reported as 1‐liner with no data.
Funding Source	Government
Notes	The authors report that there was a significant difference in the level of response in immunity in the recipients of type 15 (45.8%) and type 16 (76%) towards the serotype A (H1N1), which was probably due to vaccine antigen concentration. They concluded that "the preparation showed insignificant reactogenicity and moderate antigenic potency. The trial established that at the period of the epidemic rise of influenza B morbidity the vaccine showed, according to the data of the clinical diagnosis of influenza, insignificant effectiveness, its index of effectiveness (IE) being 1.08; according to the data of the serological diagnosis of influenza, only the A (H1N1) component of the vaccine was found to have IE equal to 1.58". This was a very difficult text to follow with many inconsistencies. Allocation and blinding are not described, denominators are not clear. See also criticism by Chumakov and colleagues in Chumakov 1987.
Risk of bias
Bias	Authors' judgement	Support for judgement
PCS/RCS‐Selection Exposed cohort	Low risk	Somewhat representative, secure record
PCS/RCS‐Selection Non Exposed cohort	Low risk	Drawn from the same community
PCS/RCS‐Comparability	Unclear risk	Only by age
PCS/RCS‐Assessment of Oucome	Unclear risk	No descriptions
Summary assessments	Unclear risk	Plausible bias that raises some doubt about the results