Evaluating the effectiveness of the “Germ-Free Hands” intervention for improving the hand hygiene practices of public health students

Figures & data

Table 1 Demographic characteristics

Student demographics	SCPH-SP	SCPH-UB
Female	54 (90%)	52 (86.67%)
Male	6 (10%)	8 (13.33%)
1st-year student	14 (23.33%)	15 (25%)
2nd-year student	17 (28.34%)	16 (26.67%)
3rd-year student	15 (25%)	14 (23.33%)
4th-year student	14 (23.33%)	15 (25%)
CPH student	25 (41.67%)	27 (45%)
DPH student	23 (38.33%)	21 (35%)
TP student	12 (20%)	12 (20%)

Abbreviations: SCPH-SP, Sirindhorn College of Public Health–Suphanburi; SCPH-UB, Sirindhorn College of Public Health–Ubonratchathani; CPH, Community Public Health; DPH, Dental Public Health; TP, Technical Pharmacy.

Table 2 Definitions and sample questions from the hand hygiene questionnaire

Variable	Definition	Sample question
Beliefs
Behavioral beliefs	Beliefs about the outcomes of handwashing behaviors and how an individual can affect handwashing outcomes.	“If I wash my hands whenever I should, I will NOT transmit any person-to-person diseases.”
Normative beliefs	Beliefs about others’ expectations that an individual perform and comply with handwashing guidelines.	“My family members have appropriate handwashing expectations at home.”
Control beliefs	Beliefs about the accessibility of handwashing facilities and supplies.	“I think the locations of the handwashing sinks in the college are convenient.”
TPB predictors
Attitudes	Personal feelings about handwashing.	“To me, washing my hands whenever I should feels good.”
Subjective norms	Perception that influential people expect appropriate handwashing behaviors.	“Most people who are important to me wash their hands whenever they should.”
PBC	Perception of the ease or difficulty of handwashing.	“I have complete control over whether or not I wash my hands whenever I should.”
Intentions to wash hands	Efforts, plans, and intentions to wash hands.	“I intend to wash my hands whenever I should.”
Handwashing practices	Practices handwashing at appropriate times, for example before eating food.	“Before every meal, how many times out of 10 do you wash your hands with soap?”

Table 3 SCPH-SP intervention group mean scores and standard deviations at baseline, immediately post-intervention, and 3 months post-intervention

Determinant	Baseline mean score (SD)	Immediate post-intervention mean score (SD)	3 months post-intervention mean score (SD)	F-test	P-value	Effect size
Knowledge	16.37 (2.50)	17.42 (2.02)	17.33 (1.86)	4.67	0.0112	0.073
Behavioral beliefs	67.28 (7.22)	68.57 (6.24)	62.00 (9.36)	11.80	0.0001	0.167
Normative beliefs	31.97 (5.05)	32.23 (5.32)	30.17 (5.01)	2.72	0.0695	0.044
Control beliefs	71.57 (9.55)	74.45 (9.86)	66.82 (12.35)	7.89	0.0006	0.118
Attitudes	38.58 (3.79)	39.15 (3.00)	37.70 (5.96)	1.79	0.1715	0.029
Subjective norms	20.60 (3.89)	21.45 (4.36)	19.12 (4.67)	4.34	0.0152	0.068
PBC	20.45 (3.40)	21.50 (3.27)	20.57 (4.06)	1.57	0.2119	0.026
Intentions	17.45 (3.45)	17.73 (2.69)	16.22 (3.47)	4.63	0.0115	0.073

Abbreviations: SCPH-SP, Sirindhorn College of Public Health Suphanburi; PBC, perceived behavioral control; SD, standard deviation.

Table 4 Observed handwashing behaviors, correct handwashing scores, and bacterial colonies on hands of students in the intervention group before eating lunch (n=60)

Behavioral indicator	Baseline	Immediately post-intervention	3 months post-intervention
Number of observed instances of handwashing over 5 days	53	280	215
Handwashing rate (per person per day)	0.18	0.93	0.72
Mean handwashing quality score (out of 20)	6.70 (33.5%)	9.41 (47.1%)	8.59 (43.0%)
Number of agar plate colonies	6 (11.32%)	28 (10%)	33 (15%)
Number of colonies on hands (colony-forming units/ml)	<2,500	<2,500	<2,500

Table 5 Comparison in self-reported handwashing practices per 10 incidences for which handwashing is required among the intervention and control groups

Situation	Intervention effect		Interaction (Intervention x time)
	beta	P-value	beta	P-value
Before preparing food	0.05	0.8975	–0.21	0.1996
Returning to food preparation after stopping to do something else	0.28	0.4251	–0.28	0.0903
After using the toilet	2.07	0.0024	–0.99	0.0005
After coughing or sneezing	0.83	0.0109	–0.38	0.0105
After touching dirty objects	1.72	<0.0001	–0.91	<0.0001
After playing with pets	1.64	<0.0001	–0.79	<0.0001
Before eating	–0.04	0.9024	–0.23	0.1622
After visiting patients	–0.47	0.0359	–0.53	0.0133

Table 6 Group differences in TPB predictors and handwashing intentions

	Baseline		Immediately post-intervention		3 months post-intervention
	SCPH-SP	SCPH-UB	SCPH-SP	SCPH-UB	SCPH-SP	SCPH-UB	Interaction P-value	Interaction effect size
Attitudes	38.58	33.35	39.15	35.75	37.70	36.77	0.0322	0.03
Subjective norms	20.60	19.27	21.45	20.12	19.12	21.13	0.0103	0.04
PBC	20.45	20.13	21.50	20.00	20.57	20.45	0.3353	0.01
Intentions	17.45	16.43	17.73	16.48	16.22	17.50	0.0049	0.04

Abbreviations: SCPH-SP, Sirindhorn College of Public Health–Suphanburi; SCPH-UB, Sirindhorn College of Public Health–Ubonratchathani; PBC, perceived behavioral control.