A prospective cohort study was undertaken among Hajj pilgrims in the year 2021. Domestic pilgrims aged ≥ 18 years of both genders who spoke Arabic or English not having any ILI symptoms at the time of recruitment were eligible to take part in this cohort study, while those who reported any ILI symptoms at the time of recruitment or refused to participate were excluded. As a result of COVID-19 restrictions and for the health and safety of pilgrims, the study was conducted distantly via phone calls by the research team. An ethics approval was obtained from the biomedical ethics committee, Umm Al-Qura University, Makkah, Saudi Arabia (Approval no. HAPO-02-K-012-2021-07-708), and other necessary permissions to perform the study were also sought. The informed consent was obtained from all subjects.
The recruitment took place during the week of Hajj rituals, from 8 to 13 of Dhul-Hijjah month of the Arabic calendar corresponding to 19 to 23 July 2021. A convenience sample was drawn from a list of around 1000 pilgrims with their names and contact information, provided by Hajj Hamlahs (tour operators). Among those pilgrims from the list who responded to the phone calls were invited to the study and provided with the study’s objectives and procedures, and those who met the eligibility criteria and gave their consent to participate were asked to be interviewed and complete the baseline questionnaire.
The baseline questionnaire contained questions about participants’ socio-demographic information, presence of pre-existing comorbidities, smoking status, vaccinations against influenza and COVID-19, and source of health information received before attending Hajj. More specific details related to COVID-19 immunisation were captured such as type/brand of vaccine received, and occurrence of adverse reactions (if any) following vaccination. Additionally, we collected data related to pilgrims’ knowledge about hand hygiene and their perception regarding the effects of soap and water, and alcohol-based hand sanitisers against RTIs.
Seven days after the recruitment, pilgrims who completed the baseline questionnaire were contacted again individually via a phone call to participate in the second phase of the study, which focused on following up pilgrims’ health and hand hygiene behaviour. The follow-up questionnaire contained questions about the presence or absence of constitutional symptoms (subjective fever, fatigue, myalgia, and headache), respiratory symptoms (cough, sore throat, rhinitis, dyspnoea, and smell or taste dysfunction) and gastrointestinal symptoms (diarrhoea, and vomiting). Details about these symptoms including onset date, duration and whether they sought treatment were obtained. Lastly, pilgrims were asked about their hand hygiene behaviour during the Hajj journey; for instance, how frequently they used soap and water, and alcohol-based hand sanitisers to clean their hands, and if they cleaned their hands before or after specific high-risk situations, such as before eating, after toilet action, after nose blowing, sneezing, or coughing and so forth.
This study used a broad definition of a case of RTI; it was defined as the development of one or more respiratory symptoms during the follow-up phase. In order to clinically diagnose a possible case of viral RTIs among our study cohorts, syndromic definitions for ‘possible’ ILI and COVID-19 were applied as per the criteria described and evaluated elsewhere [10, 11]. ILI was defined as ‘a triad of cough, sore throat and subjective fever’ as described by Rashid et al.,. The triad had a sensitivity and specificity of respectively 67% and 64% against influenza confirmed by reverse transcriptase-polymerase chain reaction. The COVID-19 infection criterion was defined as the ‘concomitant presence of three or more of the following symptoms: fever, myalgia, cough, and olfactory and taste disorders’ as defined by Fulvio et al. , which was found to be highly significantly correlated with a positive molecular diagnosis of COVID-19 (adjusted odds ratio [OR] 18.55, 95% CI 13.77–24.97) and a specificity of 91.2%.
The participant's responses were directly entered into an online questionnaire through “Microsoft Forms”, a development cloud-based software (Microsoft Office 356, version 2002, Redmond, WA, USA). Subsequently, these responses were exported to a master Excel spreadsheet (Microsoft Office 356, version 2002, Redmond, WA, USA) for data translation, cleaning, and coding before importing into Statistical Package for Social Sciences (SPSS) software (IBM SPSS Statistics for Windows, version 26.0, IBM Corp, Armonk, NY, USA) for analysis. For descriptive analysis, frequencies and percentages were applied to present categorical variables, the incidence of symptoms, and ‘possible ILI’ and ‘possible COVID-19’. The mean (or median with range) ± standard deviation (SD) was used to summarise continuous data. The associations of potential factors with the practices of hand hygiene, and with the estimated incidence of RTIs were analysed using simple logistic regression. The risk estimation was carried out using OR with 95% confidence interval (CI) and a p value of ≤ 0.05 was considered as statistically significant.
With an estimated incidence of symptomatic RTIs associated with Hajj of 30% and an error margin of 5% at a confidence level of 97%, a sample of 400 participants was needed for the study. Considering a high dropout rate, we decided to inflate the sample by 125% and targeted to recruit at least 500 subjects.