Summary of findings:

CoronaVac compared to Placebo for vaccination against COVID-19

Patient or population:
Setting:
Intervention:
Comparison:

Outcomes

Anticipated absolute effects* (95% CI)

Relative effect
(95% CI)

№ of participants
(studies)

Certainty of the evidence
(GRADE)

Comments

Risk with Placebo

Risk with CoronaVac

Incidence of participants with positive test for SARS-CoV-2 infection - not reported
-
-
-
-
-
outcome not yet measured or reported
Incidence of symptomatic COVID-19 confirmed with positive test for SARS-CoV-2 c
2,398 per 100,000
719 per 100,000
(240 to 2,110)
Rate ratio 0.30
(0.10 to 0.88)
19852
(2 RCTs)
d

LOW
b,e,f
Vaccine efficacy 50.7% (95%CI 35.9% to 62.0%) and 83.5% (95%CI: 65.4% to 92.1%)
Severe or critical disease due to COVID-19 c
134 per 100,000
0 per 100,000
(0 to 112)
Rate ratio 0.000
(0.000 to 0.831)
16729
(2 RCTs)
d

LOW
b,f,g
Vaccine efficacy 100% (95% CI 16.9% to 100.0%) and not reported
All-cause mortality h
20 per 100,000
10 per 100,000
(1 to 113)
RR 0.50
(0.05 to 5.52)
22610
(2 RCTs)
d

VERY LOW
f,i
Any adverse events j
53,362 per 100,000
58165 per 100,000
(57,098 to 59,232)
RR 1.09
(1.07 to 1.11)
23036
(4 RCTs)
k

MODERATE
f
Serious adverse events h
369 per 100,000
365 per 100,000
(232 to 572)
RR 0.99
(0.63 to 1.55)
22610
(2 RCTs)
d

VERY LOW
f,i
*The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).

CI: Confidence interval; RR: Risk ratio
GRADE Working Group grades of evidence
High certainty: We are very confident that the true effect lies close to that of the estimate of the effect
Moderate certainty: We are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different
Low certainty: Our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect
Very low certainty: We have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect

Explanations

a. Last updated: 25 July 2021
b. Despite some concerns with deviations from intervention, not downgraded for risk of bias.
c. Measured from 14 days after the 2nd dose up to median 2 months follow-up
d. Palacios R, PROFISCOV, 2021; Tanriover M, 2021
e. Inconsistency downgraded by 1 level: I²=86.7%
f. Indirectness downgraded by one level: data are from interim analyses of the trials, with a short duration of follow-up. Estimates may change over a longer duration of follow-up.
g. Imprecision downgraded by 1 level: due to low number of events and/or participants
h. Median follow-up: 2 months and 3 months
i. Imprecision downgraded by 2 levels: due to wide confidence interval consistent with the possibility for benefit and the possibility for harm and few events.
j. Median follow-up: 1.38, 1.84, 2 and 3 months
k. Palacios R, PROFISCOV, 2021; Tanriover M, 2021; Wu Z, 2020; Zhang Y, 2020 (1); Zhang Y, 2020 (2)