Table 2.
Non-intervention studies’ characteristics
| Study ID | Country | Aim of the study | Study design | Population | Sample size | Type of infection | Method of identifying infection | Relevant outcomes | Findings |
|---|---|---|---|---|---|---|---|---|---|
| Abd [33] | Iraq | To identify the risk factors predisposing to SARS-CoV-2 infection | Retrospective cross-sectional survey | General public | N = 348 hospitalised COVID-19 cases & 348 hospitalised non-COVID-19 patients | SARS-CoV-2 | Confirmed in the hospital (no details provided) | Risk factors for SARS-CoV-2 acquisition |
Amongst confirmed COVID-19 cases, 66 (18.96%) reported washing their hands “healthily”, whereas 148 (42.52%) reported doing so sometimes, compared to 94 (27.01%) and 134 (38.50%) non-COVID-19 patients, respectively. There was a statistically significant association between COVID-19 infection and hand washing (p < 0.001). |
| Badri et al. [34] | USA | To identify behaviours and evaluate trends in COVID-19-mitigating practices in a predominantly Black and Hispanic population, to identify differences in practices by self-reported ethnicity, and to evaluate whether federal emergency financial assistance was associated with SARS-CoV-2 acquisition | Retrospective cross-sectional survey | General public | N = 209 individuals who tested positive for SARS-CoV-2 & 105 who tested negative | SARS-CoV-2 | Laboratory confirmed | Risk factors for SARS-CoV-2 acquisition | Frequent use of ABHR was associated with lower odds of infection (aOR: 0.26; 95% CI: 0.13, 0.52), but frequent hand washing showed no significant effect (aOR: 0.55; 95% CI: 0.21, 1.44). |
| Castilla et al. [26] | Spain | To evaluate risk factors and measures to prevent influenza infection in the community | Retrospective case-control study | General public | N = 481 influenza outpatients & 481 controls | Influenza | Laboratory confirmed | Risk factors for influenza acquisition | The frequency of hand washing 5–10 times (aOR: 0.87; 95% CI: 0.54, 1.39; p = 0.56), and > 10 times (aOR: 0.98; 95% CI: 0.59, 1.64; p = 0.94), the use of ABHR (aOR: 1.36; 95% CI: 0.85, 2.19; p = 0.2) and hand washing after touching contaminated surfaces (aOR: 0.70; 95% CI: 0.44, 1.11; p = 0.13) had no significant protective effect. |
| Doshi et al. [28] | Bangladesh | To identify household-level factors associated with influenza among young children in a crowded community in Dhaka | Prospective case-control study | Pre-school children | N = 145 households of influenza paediatric cases & 341 control households | Influenza | Laboratory confirmed | Risk factors for influenza acquisition |
The mean hand washing frequency during a 5-hour observation period was similar between case (0.64 events) and control (0.63 events) households (p = 0.87). Mean daily soap consumption per capita was 2.92 and 2.93 in the case and control households, respectively (p = 0.92). Almost all case (97%) and control (99%) households had water present at the primary hand washing location, but 22% of case households and 29% of control households had soap present before it was provided for soap consumption measurement (p = 0.08). |
| Doung-ngern et al. [35] | Thailand | To evaluate the effectiveness of personal protective measures against SARS-CoV-2 infection in public | Retrospective case-control study | General public | N = 211 cases & 839 controls | SARS-CoV-2 | Laboratory confirmed | Risk factors for SARS-CoV-2 transmission (secondary attack rates) | A significant, negative association was found between risk for SARS-CoV-2 infection and washing hands “often” (aOR: 0.33; 95% CI: 0.13, 0.87) or “sometimes” (aOR: 0.34; 95% CI: 0.14, 0.81); p = 0.045. |
| Godoy et al. [27] | Spain | To investigate the effectiveness of non-pharmacological interventions in preventing cases of influenza requiring hospitalization | Retrospective case-control study | General public | N = 813 hospitalized influenza cases & N = 2274 controls | Influenza | Laboratory confirmed | Protective factors against influenza acquisition | The frequency of hand washing 5–10 times (aOR: 0.65; 95% CI: 0.52, 0.84; p = 0.001) and > 10 times (aOR: 0.59; 95% CI: 0.44, 0.79, p < 0.001) and hand washing after contact with contaminated surfaces (aOR: 0.65; 95% CI: 0.50, 0.84; p = 0.001) were protective factors and were dose-responsive (p < 0.001). ABHR showed no significant protective effect (aOR: 0.82; 95% CI: 0.65, 1.02; p = 0.08). |
| Karout et al. [36] | USA | To determine the prevalence, level of COVID-19 risk perception attitude and preventive behaviour implemented by the Latino population in the USA | Prospective cross-sectional survey | General public | N = 410 asymptomatic Latino adults | SARS-CoV-2 | Laboratory-confirmed | Preventive factors associated with SARS-CoV-2 acquisition | Participants who tested positive (n = 76; 18.5%) were significantly less likely to use ABHR and wash hands compared with participants who tested negative (p < 0.001). |
| Lau et al. [30] | China | To delineate the distribution of different sources of SARS transmission, identify the undefined source group and to identify relevant risk and protective factors associated with contracting SARS | Retrospective case-control study | General public | N = 330 suspected SARS cases with undefined infection sources & 660 controls | SARS-CoV-1 | SARS case definition criteria | Risk and preventive factors associated with SARS-CoV-1 acquisition | Frequent hand washing (more than 10 times a day) was a significant protective factor (OR: 0.58; 95% CI: 0.38, 0.87; p = 0.008). |
| Lio et al. [37] | China | To determine the risk and protective factors for COVID-19 infection at the individual level, with a specific emphasis on personal behaviours such as mask use, the number of gatherings, and HH practices | Retrospective case-control study | General public | N = 24 hospitalised COVID-19 patients & 1113 control participants who completed quarantine after travelling from COVID-19 high-risk foreign country | SARS-CoV-2 | Laboratory-confirmed | Risk and preventive factors associated with SARS-CoV-2 acquisition |
Compared to the non-infected individuals, those with SARS-CoV-2 infection were significantly less likely to wash hands after contact with individuals who had respiratory symptoms (50% vs. 95.3%; p = 0.005), but not after contact with suspected or confirmed COVID-19 patients (50% vs. 95.2%; p = 0.057). Hand washing after outdoor activity (aOR: 0.021; 95% CI: 0.003, 0.134; p < 0.005), hand washing before touching the mouth and nose area (aOR: 0.303; 95% CI: 0.114, 0.808; p < 0.05) were found to be independent factors for COVID-19 infection. Amongst infected individuals, 16.7% reported always washing hands for over 20 seconds each time, compared with 31.9% in the non-infected group (p = 0.125). |
| Liu et al. [38] | USA | To understand the risk of SARS-CoV-2 transmission from a paediatric primary index case to household contacts living in Los Angeles County | Prospective cohort study | Children | N = 15 paediatric index cases & 50 household contacts | SARS-Cov-2 | Laboratory-confirmed | Risk factors for SARS-CoV-2 transmission (secondary attack rates) |
Overall secondary attack rates were 34% (95% CI: 22, 48%). Transmission was significantly lower in households with increased hand washing or ABHR use compared with those who did not report increased hand washing or ABHR use (19%; 95% CI: 9, 36) vs. 58%; 95% CI: 36, 77; p = 0.01). |
| Speaker et al. [39] | USA | To compare the social behaviours of individuals who were tested positive for COVID-19 relative to non-infected individuals | Retrospective case-control study | General public | N = 113 COVID-19 cases & 226 controls | SARS-Cov-2 | Laboratory confirmed | Risk factors for SARS-CoV-2 acquisition | 67% of cases and 63% of controls reported always washing hands or using ABHR after possible exposures (p = 0.24). 75% of cases and 74% of controls reported always washing hands for at least 20 seconds (p = 0.60). |
| Wilson-Clark et al. [31] | Canada | To determine characteristics associated with the transmission of SARS within households | Retrospective cross-sectional survey | General public | N = 74 SARS-affected households | SARS-Cov-1 | SARS case definition criteria | Risk factors for household transmission of SARS-CoV-1 | Failure to wash hands after caring for ill person (RR: 3.46; 95% CI: 1.10, 10.92) and not always washing hands after changing a diaper (RR: 3.94; 95% CI: 1.28, 12.10) were associated with an increased risk of transmission. |
| Torner et al. [25] | Spain | To investigate the effectiveness of non-pharmaceutical interventions in preventing cases of influenza in children in the community setting in 2009 pandemic and 2010–2011 post pandemic/seasonal epidemic | Retrospective case-control study | Children | N = 239 confirmed paediatric influenza outpatients & 239 controls | Influenza | Laboratory-confirmed | Risk factors for influenza acquisition |
Hand washing more than 5 times per day (aOR: 0.62; 95% CI: 0.39, 0.99; p = 0.04) was the only statistically significant protective factor. For 5–17 age group, there was a negative association for influenza infection for both washing more than 5 times per day (aOR: 0.47; 95% CI: 0.22, 0.99; p = 0.04) and hand washing after touching contaminated surfaces (aOR: 0.19; 95% CI: 0.04, 0.86; p = 0.03). For the 0–4 years group there was no significant association for washing hands more than 5 times per day (aOR: 0.91; 95% CI: 0.46, 1.78; p = 0.77) nor for hand washing after touching contaminated surfaces (aOR: 1.06; 95% CI: 0.44, 2.56; p = 0.77). |
| Wu et al. [32] | China | To compare exposures of unlinked, probable SARS patients with community-based matched controls | Retrospective case-control study | General public | N = 94 probable SARS patients & N = 281 controls | SARS-Cov-1 | Laboratory confirmed | Risk and preventive factors associated with SARS-CoV-1 acquisition |
Always washing hands when returning home was a protective factor (OR: 0.3; 95% CI: 0.2, 0.7; p = 0.003). No significant association was found for always washing hands before eating (OR: 0.6; 95% CI: 0.3, 1.1; p = 0.11) or after using restrooms (OR: 0.5; 95% CI: 0.2, 1.2; p = 0.10). |
| Xie et al. [40] | China | To quantify exposure patterns, transmission characteristics, and the clinical spectrum of SARS-CoV-2 infection | Retrospective cohort study | General public | N = 20 index patients hospitalized with severe COVID-19 & 79 of their household contacts | SARS-Cov-2 | Laboratory confirmed | Risk factors for SARS-CoV-2 transmission | Hand washing ≥5 times/day was associated with reduced infection risk (52.8% vs.76.9%, p = 0.04). |
| Zhang et al. [29] | China | To assess risk factors associated with household transmission of pandemic H1N1 from self-quarantined patients in Beijing | Retrospective case-control study | General public | N = 54 case households & 108 control households | Influenza | Laboratory confirmed | Risk factors for influenza transmission | Hand washing ≥3/day was related to the household transmission of pandemic H1N1 from self-quarantined patients (OR: 0.71; 95% CI: 0.48, 0.94; p = 0.05). |
ABHR alcohol-based hand rub, aOR adjusted odds ratio, CI confidence intervals, H1N1 Hemagglutinin Type 1 and Neuraminidase Type 1 (swine flu strain), p p-value, RR relative risk, SARS-CoV-1 severe acute respiratory syndrome coronavirus 1, SARS-CoV-2 severe acute respiratory syndrome coronavirus 2