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To determine the associations between preventive measures (facemask, hand washing, and social distancing) and contracting COVID-19 infection in Saudi Arabia.

Ethical approval was obtained from the Ministry of Health (MOH) Instituional Review Board (approval number: 20-213M).

An unmatched retrospective case–control study. Administrative proposal approval from MOH was obtained on 01/11/2020 while the remaining study steps took six months until the final report was formulated on 28/4/2021 (Extended data 1).

Potential participants were selected from the Health Electronic Surveillance System (HESN) database of all COVID-19 tested individuals with confirmed results (positive or negative) in October 2020 (15,215 cases). This is the most recent data available to minimize recall bias.

Case: Any confirmed COVID-19 case in the dataset with a positive PCR result and a phone number.

Control: Any case in the dataset with a confirmed negative PCR test result and an available phone number.

After downloading the COVID-19 dataset for the assigned period, cleaning was performed to remove duplicates, outliers, and artifacts. Simple random sampling technique was used to select the samples. The required sample size was 386 under the assumptions of a 95% confidence level, alpha value of 0.05, and a COVID-19 infection proportion of 50%. However, since sufficient data were available and a low response rate was expected, we selected 6000 potential participants at random using online random number generator. ¹³ Two frames for cases (2753) and controls (3247) were constructed containing names and phone numbers of the potential participants. After obtaining the appropriate IRB (20-213M) from the Ministry of Health (MOH), the questionnaire in Google forms was sent to all potential participants via the SMS services of MOH. With a response rate of 18.3%, a total of 1102 (551 cases and 551 controls) participants responded to the questionnaire completely. The case to control ratio was 1:1 (Extended data 2).

Before commencing the questionnaire, participants' consent was sought and documented on the answer form. The questionnaire consisted of five main parts: confirmation of result, i.e., (positive/case) or (negative/control), demographic data, facemask factors, handwashing factors, and social distancing factors (Extended data 3).

Data were managed and edited using Microsoft ^® Excel ^® (Microsoft ^® Office 2016, Microsoft ^® Corp USA). (Microsoft Excel, RRID:SCR_016137) Statistical analyses were performed using Statistical Package for the social Sciences (IBM SPSS statistics 25 USA) (SPSS, RRID:SCR_002865).

Central tendency and dispersion measures were calculated for the variables, and findings were presented in suitable descriptive tables according to the study objectives. Categorical data of independent variables were compared and tested against the identified dependent variable (outcome) using univariate analysis to obtain the odds ratio as a measure of association. As the final step in the data analysis, multivariate analysis using a binary logistic regression model was implemented to adjust for possible cofounders.

In this study, younger respondents were found to be at a higher risk of contracting COVID-19 infection. This finding could be attributed to greater social activities among the young population, as documented in earlier COVID-19 studies from Saudi Arabia. ^{14 , 15} Studies from other countries like Italy, Brazil, and the USA also came to the same conclusion. ¹⁶ Moreover, the female population in our study appeared to be at higher risk of contracting the disease. Despite the COVID-19 gathering prohibition rules, females in the Saudi community tend to congregate in large numbers in their homes on a regular basis. Hence, our results hinted at a potential role of this behavior in spreading the infection compared to the male population, a finding that contradicted the previous reports from Saudi Arabia. ^{14 , 15} However, the same finding was reported in seven European countries and the United States. ¹⁷

The nationality of the respondents was also identified as an important demographic factor relevant to this study. The rate of infection was higher among the Saudi population than among non-Saudis. In general, gathering in large groups during social occasions is more common in Saudi culture. This social aspect may have increased the risk of infection among Saudis. Further, respondents with lower socioeconomic status were found to be at a higher risk of infection, which is concurrent with previous local and international studies. ^{14 , 15 , 18 – 21}

A positive attitude toward wearing a facemask is an important preventive factor. Despite the dispute on the effectiveness of facemasks at the beginning of the pandemic, their use turned to be a significant preventive factor in combating the infection worldwide. ²² The type of facemask (disposable versus cloth) showed no difference in the protective effect. A systematic review by Chu et al., ²³ investigated the use of facemasks during the pandemic and illustrated that both the surgical/disposable and cloth types provide the same level of protection. In addition, using a disposable or cloth facemask for more than one day without sterilizing or changing it showed no protective difference compared with using it for shorter periods.

Many countries mandate universal masking, especially for healthcare workers. The Center for Disease Control (CDC) recommended the public to wear masks, particularly in crowded areas. ^{7 , 24 , 25} Nonetheless, personal protective equipment is in short supply around the world, the efficacy of various types of masks, such as N95 respirators, surgical masks, and cloth masks, is still under investigation, and recommendations on the use, reuse, and sterilization of masks are inadequate. ^{24 , 25} One of the arguments regarding the facemask usage is that improper use of the mask increases the risk of COVID-19 infection by providing a false sense of protection. ⁷ On the other hand, several randomized controlled trials conducted to examine the evidence for the community's use of masks and respirators suggested protection from the virus and the likely benefits of masks in this context. ⁷

Due to strict preventive measures in work settings compared to social events and shopping places, the work environments seem to be safer regarding COVID-19 infection. Facemask use and compliance with other preventive strategies are generally taken more seriously by workplace managements. As a result, increased use of facemasks may help to slow the spread of the disease. There have been disparities in the usage of facemasks and their effectiveness against the pandemic; ^{24 , 25} however, this study supports the notion that using any type of proper facemask is effective in preventing the spread of infection regardless of its sterilization status and the period it is worn for. ²²

Self-hygiene is critical to one's overall health. Handwashing has consistently been shown to be a critical factor in preventing the spread of communicable diseases. During a pandemic, the most crucial strategy for the population is to wash their hands and frequently use hand sanitizer while avoiding contact with their face and mouth after touching potentially contaminated surfaces ⁷ . This study confirms that people who have a positive attitude toward the importance of handwashing have a lower risk of contracting COVID-19. Handwashing for longer periods (≥20 seconds) appeared to be the most effective method of combating COVID-19 infection, among other investigated preventive measures. Handwashing for an extended period is inconvenient, but it is documented as the best way to sterilize the hand surface. ^{7 , 8} In this study, the frequency of handwashing per day and the type of sterilizer or soap used compared to only water had no effect on the infection acquisition. This finding contradicts previous research that suggests that using alcohol-based sanitizer or handwashing with soap has a positive effect on reducing the transmission of respiratory infections. ^{7 , 8}

Maintaining safe distance in public places is a critical precaution as COVID-19 spreads via respiratory droplets. Several countries have implemented this strategy since the beginning of the pandemic to reduce the contact rate in the population and the potential contribution of asymptomatic and pre-symptomatic people to disease transmission. ⁷ This study suggests that residents of Saudi Arabia are aware of the importance of keeping a safe distance as a precautionary measure. The distance itself (≥2 m versus <2 m) made no difference in acquiring the infection. This finding could be attributed to strict adherence to other preventive measures like wearing a facemask and handwashing.

Interestingly, the results of this study hinted that going to school or work during the pandemic had a significant protective effect against infection. Adequate preventive measures are probably better practiced at work and school than at home; however, this point requires further investigation. Gathering with relatives and friends seems to be an important factor in acquiring the infection. This supports the Saudi MOH's claims that most of the community-acquired COVID-19 cases were from family gatherings. ²⁶ Therefore, strict penalties were imposed on those who gather in a group of more than 20 persons. ¹² Despite the negative impact of social distance on mental health, many countries, including KSA, enforced it to reduce disease transmission and protect the vulnerable population. ²⁷ Mitigating these mental health effects necessitates daily routines that include a healthy lifestyle, hobbies, virtual social interactions, and mindfulness. ²⁷

Routine social activities like shopping and visits to cafés and restaurants were supposed to be associated with a higher risk of acquiring the infection; however, the results of this study showed that they have preventive effects, probably due to strict preventive precautions at these places. The association between the risk of infection and visits to these locations may be highly dependent on adherence to disease prevention measures and designated Standard Operating Procedures (SOPs). Therefore, more research is needed on this subject. Contrarily, praying at the mosque five times a day seemed to contribute significantly to the spread of the infection. Despite strict preventive measures implemented in mosques, MOH reports revealed that mosques are potential sites of spreading the infection. ²⁶ During the curfew at the start of the pandemic, all mosques in the Kingdom, including the two holy mosques in Makkah and Madina, were closed for three months for the first time in the Kingdom's history. That was a difficult decision for both the government and the public, but it indicates commitment and seriousness of the health authority in enforcing preventive precautions against the current pandemic.

Our results evinced that COVID-19 educational messages in the media played an important role in prevention efforts. However, social media appeared to play a misleading role in this context. Because of a lack of checks and users' differing opinions, social media is a source of false and incorrect data about COVID-19. The false messages and conspiracy theories were well received by the general public, posing a significant challenge to the health authorities in KSA as well as around the world. ²⁸

A worth mentioning limitation of this study is that it lacks questions on whether the cases or contacts were subject to isolation or quarantine as an important preventive measure.