Table 1 Characteristics of studies investigating the influence of alcohol-based handrub volume

MacDonald et al

(2006) [27]

UK

NRT

Clinical

84 HCWs

1.75 ml

3.5 ml

Hand coverage

UV lightbox

Product ABHR gel containing fluorescent substance

Application time no limit given

Application technique rubbed hands as per their usual technique

Mean missed areas (%)

1.75 ml: 6.35%

3.5 ml: 1.23%

(P < 0.001)

Kampf

(2008) [19]

USA

Within-subject RCT

Laboratory

16 volunteers

2.4 ml 3.6 ml

1) Bacterial load on hands;

2) Hand coverage

1) Glove juice;

2) Visually observed for sufficiency to cover all surfaces

Product 4 ABHRs—1. 85% ethanol, 2. 60% ethanol, 3. 62% ethanol, 4. 61% ethanol, reference 4% chlorhexidine;

Application time rubbed hands until dry;

Application technique covered all surfaces;

Artificial contamination (Serratia marcescens)

Mean log₁₀ reduction (range for 4 ABHRs):

2.4 ml: 1.90–2.79

3.6 ml: 2.53–3.04

Volume had significant influence on the mean log₁₀ reduction (P < 0.001)

% of subjects with sufficient coverage of both hands

2.4 ml: 96.6%

3.6 ml: 93.6%

Rotter et al (2009) [25]

Austria

Within-subject RCT

Laboratory

1) 15 volunteers

2) 5 volunteers

1ml

2 ml

3 ml

1) Bacterial load on hands;

2) Drying time

1) Fingertips;

2) Time measured until resistance noted

Product Liquid ABHR, 2-propanol 60% (v/v);

Application time 15 s

Application technique 6-steps;

Artificial contamination (E. coli)

Mean log RF (SD)

1ml: 2.9 (0.6)

2 ml: 3.2 (0.7)

3 ml: 3.5 (0.6)

Significant between 2 ml & 3 ml (P < 0.05); and between 1ml & 3 ml (P < 0.001)

Mean (SD) drying time (seconds)

1ml: 23.4 (4.8)

2 ml: 35.0 (9.4)

3 ml: 49.4 (12.4)

Goroncy-Bermes, Koburger & Meyer

(2010) [32]

Germany

Within-subject

NRT

Laboratory

16 volunteers

2 ml

2.5 ml

3 ml

4 ml

1) Bacterial load on hands;

2) Hand size;

3) Hand coverage

1) Fingertips;

2) Hand size calculated as hand length x width;

3) Sufficiency to cover all surfaces self-reported by participants

Product 2 ABHRs 1. 96% ethanol (46.0% w/w) + 2-propanol (27.0% w/w) + benzyl alcohol (1% w/w), 2. 96% ethanol (78.2% w/w) + 2-biphenylol (0.1% w/w), Reference liquid 2-propanol 60% (v/v);

Application time 30 s;

Application technique not explicitly stated;

Artificial contamination (E. coli)

Mean log₁₀ reduction (for 2 tested ABHRs)

2 ml: 3.34 & 3.37

2.5 ml: 3.99 (only one ABHR tested)

3 ml: 3.94 & 4.47

4 ml: 4.19 & 4.52

For ABHR 1. 2 ml significantly lower reduction than for 3 ml (P = 0.009) or 4 ml (P ≤ 0.000)

For ABHR 2. 2 ml significantly lower reduction than for 2.5 ml (P = 0.006), 3 ml (P = 0.001) or 4 ml (P = 0.001)

Hand size

Male hands significantly bigger than female hands (P < 0.001)

No significant correlation between hand size and bacterial load reduction

(P > 0.05)

Number of participants reporting applied volume as sufficient to cover both hands (for 2 tested ABHRs)

2 ml: 7/16 & 4/16

3 ml: 14/15 & 15/15

4 ml: 14/15 (reported for one ABHR only)

Girard et al

(2012) [31]

France

Within-subject

NRT

Laboratory

71 IPC workers

1.5 ml

2 ml

3 ml

Hand coverage

Sufficiency to cover all surfaces including the wrists (no details)

Product 27 ABHR named but contents not reported

Application technique 6-steps + wrists

Number (%) of cases in which applied volume was sufficient

1.5 ml: 551/575 (95.8%)

2 ml: 530/538 (98.5%)

3 ml: 592/593 (99.8%)

Kampf et al

(2013) [20]

Germany/USA

Within-subject

RCT

Laboratory

15 non-HCWs

1.1ml

2 ml

2.4 ml

Single pump press

Double pump press

1) Drying time;

2) Hand coverage

1) Time measured until participants reported that their hands felt dry;

2) UV light box

Product 3 ABHR—1. 85% (w/w) ethanol gel, 2. 70% (v/v) ethanol gel, 3. 70% (v/v) ethanol foam

Application technique Covered all surfaces

Application time rubbed until dry (for measuring hand coverage outcomes)

Mean drying time (seconds)

1.1ml: 20–25

2 ml: 37–41

2.4 ml: 41–49

Single press: 20–29

Double press: 34–53

% of participants with incomplete coverage

1.1ml: 67–87%

2 ml: 27–53%

2.4 ml: 13–27%

Single press: 80–93%

Double press: 0–47%

Li, XU & Zhao

(2014) [17]

China

RCT

Clinical

74 nurses

1.8 ml

3.6 ml

1) Bacterial load on hands;

2) Drying time

1) Imprint technique;

2) Time recorded until hands were dry

Product Gel ABHR; product contents not reported;

Application technique 6-steps

Application time not applicable (drying time measured as outcome)

% reduction rate (SD)

1.8 ml: 92.2% (10.8)

3.6 ml: 96.1% (5.6)

(P = 0.049)

Drying time (seconds)

1.8 ml: 44.1

3.6 ml: 75.3

(P < 0.001)

Macinga et al (2014) [22]

USA

Within-subject

RCT

Laboratory

13 volunteers

Different volumes (unspecified) of 6 ABHRs

Drying time

Time measured until participants reported that their hands felt dry

Product 6 ABHRs 1. 62% (v/v) ethanol foam; 2. 70% (v/v) ethanol foam; 3. 70% (v/v) ethanol gel; 4. 90% (v/v) ethanol gel; 5. 70% (v/v) ethanol rinse; 6. 80% (v/v) ethanol rinse

Application technique rubbed hands until dry

ABHR volumes indicated to dry in 30 s ranged from 1.7 to 2.1ml

Drying rate (seconds/ml) ranged from 12.2 (95% CI, 9.8–14.7) to 18.2 (95% CI, 15.5–21.0)

Bellissimo-Rodrigues et al

(2015) [29]

Switzerland

Within-subject

NRT

Laboratory

15 HCWs

0.5 ml to 3 ml, in 0.5 ml variations

(with addition of 4, 5, and 6 ml for large hands)

1) Bacterial load on hands;

2) Hand size

1) Fingertips;

2) Hand surface area calculation

Small < 375cm²

Medium 376–424 cm²

Large > 425 cm²

Product liquid ABHR, 2-propanol 60%;

Application time 30 s;

Application technique 6-steps;

Artificial contamination (E. coli)

The mean bacterial reduction was 0.28 log₁₀ for each additional 0.5 ml of ABHR

(95% CI, 0.20–0.36; P < 0.001)

Hand size

Mean log₁₀ reduction per each additional 0.5 ml of ABHR:

Small hands 0.40 (95% CI, 0.27–0.52; P < 0.001)

Medium hands 0.32 (95% CI, 0.21–0.42; P < 0.001)

Large hands 0.15 (95% CI, 0.03–0.26; P = 0.011)

Bacterial reduction was inversely and significantly associated with hand surface area (− 0.003 [95% CI, − 0.006– − 0.0005], P = 0.019)

Wilkinson et al

(2017) [34]

UK

Within-subject

NRT

Laboratory

1) 5 volunteers

2) 15 volunteers

3) 15 volunteers

0.5 ml to 3 ml, in 0.5 ml variations

1) Bacterial load on hands;

2) Hand size;

3) Drying time

1) Fingertips;

2) Hand surface area = 2.48 × hand length x hand breadth;

3) Time measured until participants reported that their hands felt dry

Product 3 ABHRs—1. ethanol, 80% (v/v); glycerol, 1.45% (v/v); hydrogen peroxide, 0.125% (v/v)

2. isopropyl alcohol, 75% (v/v); glycerol, 1.45% (v/v); hydrogen peroxide, 0.125% (v/v)

3. Reference liquid 60% IPA: isopropyl alcohol, 60% (v/v);

Application time 30 s (except when volumes were tested for drying times)

Application technique 6-steps;

Artificial contamination (E. coli)

Log₁₀ RF (for 3 tested ABHRs):

0.5 ml: 2.15–2.80

1ml: 2.22–2.98

1.5 ml: 2.82–3.08

2 ml: 3.22–3.81

2.5 ml: 3.80–4.27

3 ml: 3.91–4.60

Significant correlation between volume and bacterial reduction

(P < 0.001)

Hand size

Log₁₀ RF was not significantly associated with hand size (P = 0.9782)

Drying times (seconds), (for 3 tested ABHRs)

0.5 ml: 10.07–11.40

1ml: 16.33–17.53

1.5 ml: 20.73–27.07

2 ml: 26.93–31.00

2.5 ml: 33.13–37.20

3 ml: 36.60–45.73

Drying time had a significant, positive association with volume (P < 0.001)

Wilkinson et al

(2018) [35]

UK

Within-subject

NRT

Laboratory

15 volunteers

0.5 ml to 3 ml, in 0.5 ml variations

Drying time

Time measured until participants reported that their hands felt dry

Product 2 ABHRs—1. 60% (v/v) isopropanol; 2. 80% (v/v) ethanol + 1.45% (v/v) glycerol + 0.125% (v/v) hydrogen peroxide (each in liquid, gel & foam format)

Application technique 6-steps;

Mean drying times (seconds), for 2 tested ABHRs in 3 formats)

1.5 ml: 19.67–31.53 3 ml: 35.07–63.13

Increasing the volume increased the drying time (P < 0.001)

Jain, Clezy & McLaws (2018) [28]

Australia

Crossover NRT

Clinical

40 HCWs

2 dispenser pump presses vs. 3 dispenser pump presses

Bacterial load on hands

Fingertips

(cultured for MRSA and VRE)

Product foam ABHR; product contents not reported

Application time rubbed until hands were dry

Application technique 6-steps

Number of plates with MRSA or VRE growth:

2 dispenser pumps: 2/40 grew 1 colony-forming unit of MRSA

3 dispenser pumps: No growth

Suchomel et al

(2018) [33]

Austria

Within-subject

NRT

Laboratory

15 volunteers

1ml

2 ml

3 ml

1) Bacterial load on hands;

2) Hand size;

3) Drying time

1) Fingertips;

2) Hand surface area calculation

Small < 375cm²

Medium 376–424 cm²

Large > 425 cm²;

3) Time measured until participants reported that their hands felt dry

Product ABHR 2-propanol 60% (v/v) liquid;

Application time not applicable (drying time measured as outcome)

Application technique 6-steps

Artificial contamination (E. coli)

Mean log₁₀ RF (SD)

1ml: 1.99 (0.66)

2 ml: 2.96 (0.84)

3 ml: 3.28 (0.96)

Mean log₁₀ RFs were greater when larger volumes were used (P < 0.0001), but no significant difference between 2 ml & 3 ml (P = 0.08)

Hand size and log₁₀ RF (P = 0.698). Hand size and RF accounting for dry-times and volumes (R² = 77%, P = 0.403)

Mean (SD) drying (seconds)

1ml 24 (7)

2 ml 50 (14)

3 ml 67 (20)

(P ≤ 0.030)

Mean drying times were greater when larger application volumes were used (P < 0.0001)

Regardless of volume

Reduction fraction increased 0.29 log₁₀ per 10 s increased drying time

Kenters et al (2020) [21]

Netherlands

Within-subject RCT

Laboratory

1) 9 HCWs;

2) 10 HCWs

0.75 ml

1.5 ml

2.25 ml

3 ml

1) Drying time;

2) Hand coverage

1) Time measured until participants reported that their hands felt dry;

2) Hands photographed under UV light

Product 65% ethanol, + 10% n-propanol (in gel, foam & liquid formats). For hand coverage outcome—ABHR in gel & foam format mixed with a 2% concentration UV marker; product contents not reported

Application time rubbed until dry (for hand coverage outcome)

Application technique 6-steps

0.75, 1.5 & 2.25 ml dried within 20–30 s

3 ml dried between 37 and 56 s

Hand coverage

At least 2.25 ml required for optimal coverage. Foam covered 90% & gel 82% hands