Review Article

Factors influencing mask use and physical distancing for COVID-19: A qualitative evidence synthesis

Dachi I. Arikpo, Okwu A. Onyema, Afiong O. Oku, Chibueze Meremikwu, Hannah Hamilton-Hurwitz, João P. Toledo, Kathleen Dunn, April Baller, Helen J. Smith, Martin M. Meremikwu

Received: 12 May 2024; Accepted: 21 Jan. 2025; Published: 14 Apr. 2025

Copyright: © 2025. The Author(s). Licensee: AOSIS.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Background: The World Health Organization (WHO) recommends a bundle of precautions to reduce community transmission of COVID-19, including mask use and physical distancing. However, there is evidence that suggests poor adherence to these health measures community settings.

Aim: To summarise qualitative research evidence on the perceptions and factors influencing masks use and physical distancing in the context of the COVID-19 pandemic.

Setting: We included studies conducted in community settings.

Method: An electronic database search was conducted using search terms derived from the inclusion criteria and combined in a peer-reviewed search strategy. Thirty studies were sampled. Qualitative data analysis was performed using the thematic synthesis approach. The confidence in each review finding was ascertained using the Grading of Recommendations, Assessment, Development and Evaluations – Confidence in the evidence from Reviews of Qualitative Research (GRADE-CERQual) approach.

Results: Ten analytical themes of low to high confidence were identified. Values, belief systems and cultural norms shaped the perception and uptake of mask use and physical distancing. Key barriers included the cost of masks, limited infrastructure for spatial separation and inconsistent political or government messaging, while visual cues and social responsibility facilitated adherence.

Conclusion: Personal values and preferences influenced individuals’ adherence to these public health measures. Political or government messaging is important to aid understanding and adherence.

Contribution: Insights provided by this synthesis can support future emergency preparedness and response to outbreaks of acute respiratory infections by providing policy makers with information needed to make contextually relevant recommendations to enhance adherence.

Keywords: COVID-19; SARS-CoV-2; infection prevention and control; face masks; masks; physical distancing; PPE; qualitative evidence synthesis; systematic review.

Introduction

The World Health Organization (WHO) recommends using a bundle of interventions, such as mask wearing and physical distancing to reduce community transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).¹ Implementation and adherence to these public health and social measures (PHSM) can reduce the spread of SARS-CoV-2, especially in community settings.²

Masks serve as a source control measure by providing a protective barrier against respiratory infectious particles.³ Medical masks are typically available for purchase and use by the general public; however, the unforeseen nature of the COVID-19 outbreak led to acute shortages of masks and the need to improvise by using non-medical masks (i.e., cloth masks).^4,5 Other public health measures, such as physical distancing, limit close contact between individuals, potentially lowering the risk of transmitting respiratory infections.^1,6

In response to the COVID-19 pandemic, mask use and physical distancing policies were instituted at global, regional and national levels to contain the spread of the virus. However, poor adherence to this public health advice, especially in non-healthcare settings, was observed and reported.^7,8 Therefore, it is critical to investigate the reasons and factors influencing non-implementation in order to strengthen policies and their implementation.

Ill adherence with mask use and physical distancing policies in the context of COVID-19 may stem from varying perceptions of the effectiveness, acceptability and feasibility of these PHSM and the lived experiences of community members following their implementation. Synthesis of evidence from qualitative research is important to broaden our understanding of contextual factors that may influence uptake of mask use and physical distancing across different settings. The WHO also uses a robust methodology for guideline development, which includes using qualitative data to inform relevant domains of the Evidence-to-Decision framework.⁹ This review was commissioned by WHO to bridge the knowledge gap in the evidence base for the 2023 update of the living guidelines on infection prevention and control in the context of COVID-19.¹ The database search performed at the time of conducting this study showed no existing QES on perceptions and factors influencing uptake of mask and physical distancing in community settings in the context of COVID-19. It was also necessary to synthesise the documented lived experiences, perceptions and challenges affecting the implementation and uptake of these PHSM to inform future emergency preparedness.

Aim

This qualitative evidence synthesis (QES) aimed to (1) synthesise the perceptions and experiences of the general public on the use of masks and physical distancing in community settings in the context of COVID-19 and (2) identify the contexts and conditions that influence uptake of these infection prevention and control (IPC) measures.

Methods

Study design

Qualitative evidence synthesis was performed using the methodology prescribed by Cochrane,^10,11,12 and reported according to the stipulations of the ‘Enhancing transparency in reporting the synthesis of qualitative research’ (ENTREQ) and Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklists.^13,14 The review protocol was registered on the International Prospective Register of Systematic Reviews (PROSPERO, CRD42022356383).

Inclusion criteria

The SPICE (setting, perspective, phenomenon of interest, comparison and evaluation) framework,¹⁵ was used to determine the inclusion criteria (Table 1). The literature search was targeted at primary studies published in response to the COVID-19 pandemic to inform the update of the WHO COVID-19 IPC guidelines. Only relevant studies published from 01 January 2020 to the date of the search (05 September 2022) were considered for inclusion in the QES.

Search strategy

Information scientists from Cochrane (G.C., M.C., E.C.) collaborated to design and implement the peer-reviewed search strategy (Appendix 1) on the topic of interest in health and care, and community settings. The electronic search was performed on one database – MEDLINE (Ovid). In addition, the reviewers searched the reference list of related full-text publications to identify any additional studies for inclusion.

Study selection and sampling

Records retrieved by the search were uploaded to the Endnote Reference Management software.¹⁶ The records were deduplicated, and the eligibility criteria were applied to the remaining records. Working in pairs, one author (either C.M. or O.A.O) screened all titles, abstracts and full texts of potentially eligible studies using a pre-piloted eligibility screening form, while a second author (either D.I.A. or A.O.O.) validated screening output. Inconsistencies in the selection process were resolved by consulting a third review author (H.J.S.).

Through full-text screening, 78 studies were included in the review; the authors considered this number too many to analyse efficiently. Therefore, maximum variation purposive sampling was applied to select studies for the synthesis.^17,18 A three-step sampling frame with the following parameters ‘data richness’, ‘closeness of the study to our synthesis objective’ and ‘geographical spread or representation’ was developed and used. Data richness was ascertained using the data richness scale by Ames and colleagues.¹⁹ Prior to applying the sampling criteria, each included study was categorised into intervention groups (PPE and masks in healthcare settings, masks in the community and physical distancing in healthcare and community settings). Physical distancing was not restricted to maintaining a distance of 1 m or 2 m but was a general concept of maintaining space between persons. Excluded studies, studies not sampled and the reasons for excluding or non-sampling were duly documented.

Data extraction

Characteristics and outcomes reported by the sampled studies were inputted into a pre-piloted data extraction spreadsheet in Microsoft^® Excel. Themes and supporting quotes were then extracted into two other spreadsheets. One review author (O.A.O) extracted data from the sampled studies, and two authors (D.I.A., A.O.O.) verified all extracted data for accuracy and completeness. Discrepancies were corrected by the verifying authors or by consulting the wider author team.

Assessment of methodological limitations of sampled studies

An adapted version of the Critical Appraisal Skills Programme (CASP) tool for qualitative studies was used to assess the methodological limitations of the sampled studies.²⁰ The tool evaluates the appropriateness or adequacy of descriptions of the study context, sampling strategy, data collection and analysis, evidence supporting the findings, reflexivity and ethical considerations. Two authors (O.A.O and D.I.A.) appraised the studies independently and reached a consensus on the final judgement for each domain. The quality assessment was not an eligibility criterion for including studies in this QES.

Data analysis

Two review authors (D.I.A., O.A.O) performed the initial coding of extracts independently. They identified discrepancies in coding and reached a consensus on the coding approach. Subsequently, one author (D.I.A.) coded extracted texts from the sampled studies line by line while a second author (H.J.S.) verified the coding. Codes were iteratively identified, developed and reviewed in accordance with the extracted text’s contents and meaning.

A thematic synthesis for perception and experiences of mask use and physical distancing was performed.²¹ This synthesis approach is highly recommended by Cochrane and allowed for descriptive themes to be induced directly from the data and organised using ‘constant comparison’ methods.²² Analytical themes were subsequently developed by re-grouping descriptive themes. The thematic synthesis method was well-suited for delving into the viewpoints and encounters of stakeholders, and adequately supports the development of descriptive and analytical themes.^23,24

Data concerning the factors affecting uptake of mask and physical distancing were synthesised through a deductive approach, aligning descriptive themes with a pre-existing framework. The Supporting the Use of Research Evidence (SURE) framework,²⁵ was deemed the best-fit framework for this synthesis. The SURE framework was selected because it identifies factors that influence the implementation of a policy option at the level of the individual, and the social and political context. Data were extracted against the SURE framework domains and, from these, developed descriptive and then analytical themes. The hybrid approach of the synthesis, coding process and development of descriptive and analytical themes was discussed and agreed to by all authors.

Assessing the confidence in the review findings

Use of GRADE-CERQual determined the confidence level (high, moderate, low or very low) for each review finding (analytical theme).²⁶ One review author (D.I.A.) evaluated the confidence of each finding across four domains. A second author (H.J.S.) verified the judgements and ratings. The overall assessment was determined by the author team’s consensus.

Review author reflexivity

The author team is a multidisciplinary team of researchers working in evidence-based healthcare. They include academics and clinicians with backgrounds in social sciences, public health, nursing and medicine, and have experience in conducting scientific research, including qualitative research, synthesis of qualitative research and epidemiology. The majority of the author team also have considerable knowledge of existing social, behavioural conceptual frameworks that explain health behaviour. As a review team, we understood that our perspectives and experiences of the COVID-19 pandemic may influence how we collect, analyse and interpret the data. All the authors had experienced the COVID-19 pandemic and generally considered IPC strategies essential for mitigating the spread of the virus, but did not have clear expectations of the review findings. The authors were mindful of their inclinations throughout the conduct of the QES and minimised potential biases in the analysis and interpretation of the review findings using the refutational analysis approach.²⁷ We believe the multidisciplinary nature of the team allowed for rich insights and balanced views on the findings and interpretation of the evidence. All synthesis findings were discussed and agreed on as a team.

Ethical considerations

This article followed all ethical standards for research without direct contact with human or animal subjects.

Results

Included studies

The database search returned 1067 records, including studies conducted in both community and health and care settings. Following the screening of titles and abstracts, full-text and sampling, 30 studies were included and synthesised for both settings. Post hoc, we realised it would be more efficient to present the synthesis results for health and care settings, and community settings in separate reports. In this review, we present the results of the synthesis of 11 studies on mask use and physical distancing in community settings.^{28,29,30,31,32,33,34,35,36,37,38} The perceptions and experiences of personal protective equipment (PPE) use and physical distancing in healthcare settings (n = 19) are reported in a separate synthesis.³⁹ The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flow diagram (Figure 1) details the study selection process.

FIGURE 1: Preferred Reporting Items for Systematic Reviews and Meta- Analyses (PRISMA) flow diagram.

Following the World Bank classifications, four of the sampled studies were set in three low-income countries (LICs): Ethiopia,^29,32 Mali³⁶ and the Democratic Republic of the Congo,³⁷ (Table 2). Another study³⁰ was set in a lower-middle-income country (LMIC) – Tanzania. One study,³⁸ was from an upper-middle-income country (UMIC) – South Africa. Four studies were from three high-income countries (HICs): the United States (US),³¹ United Kingdom (UK)^33,35 and Ireland.³⁴ One of the studies was a multi-country study (including participants from 20 European countries and two Asian countries) conducted across different income settings.²⁸

Four of the sampled studies reported perceptions and experiences of mask use,^28,29,30,31 and seven studies reported the perception of physical distancing.^{32,33,34,35,36,37,38} All sampled studies were primary qualitative studies except four studies that were mixed-method studies.^31,32,35,37 Study participants were individual community members, young people, people with disabilities, physically active adults, people living in informal settlements internally displaced persons (IDPs), IDP camp managers, refugees, members of the refugee central committee, community leaders, religious leaders, community health workers, traffic police, drivers, humanitarian organisation staff members and researchers (Table 2).

The methodological quality of the studies ranged from minor methodological limitations (n = 8 studies) to moderate limitations (n = 3 studies) (Table 2). Most studies provided descriptive information on the study context, sampling strategy, data collection and analysis approaches and ethical considerations. They also offered underlying data to support their findings. Only two studies explicitly reported on researcher reflexivity.^33,34 The QES authors discussed the implications of the absence of reflexivity on each finding supported by studies that did not report on researcher reflexivity.

Review findings

Ten analytical themes emerged from the synthesis: six related to community members’ perception and experience of mask use and four on physical distancing (Table 3). The analytical themes, corresponding descriptive themes and sample quotes are also presented in Table 3. The outcome of the GRADE-CERQual assessment is presented with each review finding and details are shown in the Summary of Qualitative Findings Table (Table 4). Four findings were rated as high confidence, four as moderate confidence and two as low confidence. The key reasons for downgrading the certainty of evidence were methodological limitations and data adequacy.

Mask use by the general public

Finding 1: Belief systems discourage mask wearing (moderate confidence): In one study conducted in Ethiopia (LIC), belief systems enforced by culture, norms and perceived low severity of COVID-19 discouraged the use of masks.²⁹ The study described how the Nuer ethnic groups perceived death as a normal occurrence; therefore, they were not afraid of dying from COVID-19. Community members narrated their perceptions on preventive measures, referring to them as unnecessary as ‘death is not a new thing’. A male youth reported on the community’s perception of COVID-19 stating ‘the community does not believe that the disease is serious enough to kill the people’; therefore, community members were indifferent to adopting preventive measures like mask wearing.²⁹

Finding 2: Safety but false security in mask wearing (low confidence): One cross-continental study reported that some community members (researchers) felt that the protection provided by masks had been exaggerated and gave a façade for protection from COVID-19 infection.²⁸ Therefore, a false sense of security was associated with mask wearing. The researchers described how this idea led to individuals ‘letting their guard down’ and not partaking in additional public health measures, like physical distancing. However, researchers narrated how they would rather adopt a package of public health and social measures, including physical distancing, than promote masks as a standalone measure.

Finding 3: Masks affect social relationships (moderate confidence): In one study, community members perceived mask use as a barrier to social relations.²⁸ They recounted their observations of physical distancing and mask use leading to a sense of estrangement among people, noting how acquaintances or friends tended to withdraw from social interactions when wearing masks.

Finding 4: Coping with mask wearing during physical activity (low confidence): In one study from a HIC, persons who engaged in physical activity while wearing a mask reported varying experiences.³¹ Some persons expressed how they experienced discomfort but that the discomfort experienced was not significant enough to deter them from engaging in their exercise routines. The discomfort experienced included feeling light-headed, increased anxiety, sweat and the fact that ‘the mask was irritating to wear’. One participant narrated that they coped well and reported they experienced boosted physical endurance levels.

Finding 5: The cost of masks is a barrier for some (moderate confidence): The affordability of masks was described as a barrier to adherence to mask mandates across HICs and LICs.^28,29,30 For some community members, families of large size and persons living with disabilities who were often enthusiastic about wearing masks noted they were expensive and simply not affordable. Confronted by the costs associated with purchasing masks, individuals narrated how they prioritised their sustenance over purchasing masks. Some individuals expressed concern over the absence of regulation and price control in the mask market, particularly noting how retail outlets capitalised on the high demand by selling masks at inflated prices, particularly during the initial stages of the pandemic.

Finding 6: Social and political aspects of mask wearing (moderate confidence): One multi-country study described the social and political factors influencing mask use.²⁸ The study reported how community members perceived wearing masks as a social responsibility borne out of the need to protect themselves and others from being infected with the virus. This perception contributed to the idea that not using masks in line with mandates was social deviance. The study also narrated how community members disagreed with mask mandates at a point and did not appreciate the need for continued enforcement when the spread of the virus was personally viewed as ‘reasonably contained’. Community members were also not very receptive when others requested that they comply with mask wearing. The use of masks varied depending on the political context, for example, in some Asian countries like China and South Korea, mask use was a routine for protection against pollutants and the prevention of seasonal flu and common cold.⁴⁰ Therefore, adherence was less problematic; however, the acceptance of masks in other geographic settings like the West was obscured by political, religious and ethnic undertones, influencing use.

Finding 7: Beliefs and cultural norms compete with the logic of physical distancing in community settings (high confidence): Community members in HICs and LICs seemed to value cultural norms and beliefs that impacted personal perceptions of physical distancing and precluded its practice.^{32,33,34,36,37} These beliefs included not observing physical distancing while praying in the mosque to guarantee the receipt of prayers by God, eating meals together and sharing hugs, especially in settings with strong familial and social ties. A male IDP from Mali described how eating together reinforced bonds. Another individual from the UK also narrated how hugging is a part of the culture; hence, adherence to physical distancing was difficult. A resident of a conflict-affected area in the DRC described how security was a greater priority than physical distancing. Adherence with physical distancing guidelines also waned with time because of personal changes in perceptions of susceptibility and risk, including individuals questioning why physical distancing was still enforced when transmission rates were perceived as low and ‘the urgency’ had abated. However, individuals with high-risk perceptions tried to protect themselves and others by complying with physical distancing guidance.

Finding 8: Solidarity in not physically distancing (high confidence): Community members in HICs reported that they experienced difficulty complying with physical distancing among family, friends and colleagues.^33,34,35 This was because of peer and social pressure and the ‘sense of camaraderie’ in not observing physical distancing while interacting with family or acquaintances. Friends and acquaintances who had ridden in the same vehicle to a location recounted how they found it contradictory to enforce physical distancing among themselves when they were out of the car. Community members also described how the actions of others – neighbours, friends and colleagues – influenced their adherence or non-adherence to physical distancing guidelines. The study participants recounted being uncertain if it is ethical to insist that an individual maintains a distance from you during an interaction.

Finding 9: Physical infrastructure prevents physical distancing (high confidence): IDPs and community members in four studies conducted across LICs, a UMIC and a HIC described how it was not feasible to maintain physical distancing in public spaces at the time of the study.^33,36,37,38 Overpopulated and overcrowded community settings like IDP camps and informal settlements lacked the spatial capacity to maintain a distance between persons. Even if they did, basic amenities in these settings, like toilets, bathrooms and water sources, were shared and not exclusive to households. An IDP expressed how he feared they [IDPs] would ‘all die’ if there was a COVID-19 outbreak in the camp because it would spread easily because of the inability to maintain physical distance, amongst other infrastructural issues.

Finding 10: Social and political factors and physical distancing in community settings (high confidence): Individuals who were willing to maintain the recommended physical distance narrated how its practice was difficult in small areas and public spaces lacking environmental controls like visual cues, Plexi glass divisions and other forms of spatial separation.^32,33,34,35 Community members (young people) shared the perspective that the physical environment should support adherence with physical distancing. They suggested the use of ‘technological reminders like an app’ to prompt individuals when they are non-compliant, floor stickers, marking tapes and other prompts to adherence. Individuals also reported that they experienced confusion because of frequently changing and contradictory messages on physical distancing from government and regulatory agencies and desired unambiguous and more concise guidelines.

Discussion

Summary of main results

The finding of this QES shows that masks were less valued and accepted by community members because of cultural beliefs and the perceived low severity of COVID-19. Community members described experiencing: reduced engagement, communication difficulties, changes in interpersonal relationships and poor support for social relations when they wore masks. Cultural beliefs and norms often competed with the logic of physical distancing. The acceptability of physical distancing was poor in community settings as individuals struggled to comply with guidelines when they were among colleagues, friends or family members. Using visual cues and environmental prompts to create space awareness for physical distancing was generally acceptable to all stakeholders.

Factors influencing the uptake of masks and physical distancing

Several factors influenced community members’ uptake of masks and physical distancing in low-income and high-income settings. Firstly, the costs of masks was a critical barrier; prices of masks were inflated along the supply chain, highlighting the need for price regulation. For instance, the cost of medical masks in Tanzania was reported as 500.00 Tanzania Shilling (~$0.22), and disadvantaged groups (people with disabilities, internally displaced persons and large families) described how they could not afford them.³⁰ In another instance, daily sustenance was prioritised over the purchase of masks because of costs. Secondly, the political and social connotations of masks constituted either a barrier or facilitator based on the study setting. Community members who perceived mask wearing as a social responsibility were more compliant. In some Asian countries, masks were routine before the COVID-19 pandemic, so there were fewer challenges to uptake during the pandemic. Alternatively, there was deviance in settings with divergent and strong political standpoints.

Public spaces and infrastructure, especially in IDP camps and informal settlements, did not support spatial separation; therefore, physical distancing was not feasible. Pre-existing public infrastructure and workspaces could not be expanded or remodelled to accommodate physical distancing requirements. Furthermore, health authorities frequently reviewed guidelines on physical distancing at the onset of the pandemic, which caused miscommunication.

Implications for practice

The sudden emergence of the pandemic necessitated emergency responses worldwide, leading to significant challenges in implementing public health measures. Furthermore, current epidemiology suggests that COVID-19 may be a sustained concern.⁴¹ Given the experience and perception of mask use and physical distancing highlighted in this review, it is important to explore options for overcoming the barriers and enhancing the facilitators to adhere with public health guidelines. For the implementation of these public health and social measures at the community level, formative research, orientation and interactions with key community members may aid in the identification of these dissenting beliefs.⁴² Given the importance of political, social and government messaging identified in this study, further research may inform health communication and messaging strategies to aid understanding and overcome barriers to adherence with public health measures.

Overall completeness of the evidence and implications for research

The studies included in this QES span different socio-economic settings and countries. Studies reporting on mask use and physical distancing were from both HICs and LICs. Most of the studies on masks did not specify the type of mask under consideration. Therefore, we are unable to attribute perceptions or experiences to a specific type of mask. The scope of physical distancing in this review was not limited to maintaining a distance of 1 m or 2 m between individuals as recommended by public health guidelines. This review identified the following research gaps: none of the sampled studies assessed whether cost or other forms of resource requirements for physical distancing were an impediment to complying with physical distancing guidelines. We did not find any primary qualitative studies on the perceptions of environmental controls and other forms of physical barriers. Therefore, there is a need for qualitative studies on the subject.

Limitations of the study

This rapid review was conducted in response to the update for IPC guidelines for COVID-19. In keeping up with the rapid review methodology, we searched only one database – Ovid MEDLINE. The electronic search was also restricted to studies published in English language within a specific time frame and we only analysed a representative sample of studies. These steps may have limited the range of studies we identified, assessed for eligibility and included in this qualitative evidence synthesis. The review team maintained methodological rigour in conducting the review by using standard Cochrane Methods; the review authors believe that the rigour helped reduce the biases that may be associated with studies of this nature. None of the sampled studies assessed the reported perception of cost or other forms of resource requirements for physical distancing. We also did not identify any primary qualitative studies on the perceptions of environmental controls and other forms of physical barriers.

Conclusion

This QES presents themes encompassing perceptions, barriers and facilitators concerning the use of masks and physical distancing in community settings. Values and belief systems shaped the perception and uptake of masks in community settings and stood out as a barrier to mask use across different geographic groups. The uptake of physical distancing was primarily hindered by the lack of physical infrastructure to aid space awareness and spatial separation. Primary qualitative studies are needed to understand community members’ perceptions of environmental and engineering control interventions in the context of COVID-19. This QES provides insight into the contextual factors that influence the uptake of PHSM. This information can support future emergency preparedness and response to outbreaks of acute respiratory infections; and it can also be used by public health professionals to design context-specific policies that are both relevant and feasible for implementation in their communities.

Acknowledgements

The authors thank colleagues at Infection Prevention and Control, Country Readiness Strengthening, World Health Organization, World Health Emergencies Programme, Geneva, Switzerland, for their support during the preparation of the review. They acknowledge the information scientists – Graham Chan, Moriam Chibuzor and Elise Cogo – who conducted the database search for this qualitative evidence synthesis. They also acknowledge Edward Odey for his contribution to the study selection process.

The authors reported that they received funding from a grant from Country Readiness Strengthening, WHO World Health Emergencies Programme, Geneva, Switzerland to Cochrane Nigeria which may be affected by the research reported in the enclosed publication. The authors have disclosed those interests fully and implemented an approved plan for managing any potential conflicts arising from their involvement. The terms of these funding arrangements have been reviewed and approved by the affiliated university in accordance with its policy on objectivity in research.

Study conception and design was by M.M.M., A.B., H.H.-H., J.P.T., K.D., H.J.S. and D.I.A. C.M., O.A.O., A.O.O. and D.I.A. screened studies for inclusion and collected data. Data analysis and interpretation was conducted by D.I.A., A.O.O., H.J.S., M.M.M., H.H.-H., K.D., J.P.T. and A.B. D.I.A. wrote the first draft of the manuscript with input from O.A.O., C.M., A.O.O., H.J.S., M.M.M., H.H.-H., J.P.T., K.D. and A.B. performed a critical revision of the article. All the authors read and approved the final version to be published.

The authors reported that they received funding from a grant from Country Readiness Strengthening, WHO World Health Emergencies Programme, Geneva, Switzerland to Cochrane Nigeria.

Data supporting the findings of this study are available from the corresponding author, D.I.A., upon request.

The views and opinions expressed in this article are those of the authors and are the product of professional research. It does not necessarily reflect the official policy or position of any affiliated institution, funder, agency or that of the publisher. The authors are responsible for this article’s results, findings and content.

References

APPENDIX 1: MEDLINE search strategy

Date of search: 05 September 2022

1. Air Filters/ or Air Ionisation/ or Ventilation/

2. (HVAC or HEPA or MERV or CADR or HRV or ERV or "Heating ventilation and air conditioning" or "High Efficiency Particulate Air" or "High Efficiency Particulate Arrestance" or "Minimum

   Efficiency Reporting Value" or "Clean Air Delivery Rate" or "Heat Recovery Ventilator" or "Energy

   Recovery Ventilator").ti,ab,kf.

3. (ventilation adj2 (unit* or system* or technolog* or vents or equipment or device*)).ti,ab,kf.

4. (air adj2 (cleaner* or cleaning or filter* or filtering or filtration or purifier* or purifying or purification or ultraviolet or ultra violet or UV or UVGI or UVC or actinic or ioni?er* or ioni?ing or ioni?ation or ozone or ozoni?er* or ozoni?ation)).ti,ab,kf.

5. (ion generator* or electrostatic precipitator*).mp.

6. or/1-5

7. air pollutants/ or air pollutants, occupational/

8. air pollution/ or air pollution, indoor/

9. Air/ or Air Microbiology/

10. Aerosols/ or Inhalation Exposure/

11. or/7–10

12. filtration/ or Ultraviolet Rays/ or Ultraviolet Therapy/

13. 11 and 12

14. 6 or 13

15. patient isolators/ or protective devices/ or masks/ or personal protective equipment/ or exp protective clothing/ or exp respiratory protective devices/

16. ((protective adj2 (clothing or equipment or device?)) or PPE or glove? or gown?).ti,ab,kf.

17. (mask? or facemask* or "face mask*" or respirator? or N95 or N99 or FFP2 or FFP3 or "Filtering face piece?" or "Filtering facepiece?" or faceshield? or "face shield?" or goggles).ti,ab,kf.

18. or/15–17

19. ((engineering or environmental) adj2 control?).ti,ab,kf.

20. physical distancing/

21. ((physical* or social* or spa?ial) adj2 (barrier? or distanc* or separation or proximity)).ti,ab,kf.

22. (distancing adj2 (intervention? or measure?)).ti,ab,kf.

23. or/19-22

24. 14 or 18 or 23

25. limit 24 to COVID-19

26. Health Knowledge, Attitudes, Practice/ or health behavior/ or health risk behaviors/ or exp Guideline Adherence/

27. ("adhere to" or adherence or attitude* or barriers or challeng* or compliance or comply*or facilitat* or influenc* or knowledge or perception* or practice*).ti,ab,kf.

28. 26 or 27

29. 25 and 28

30. exp animals/ not humans.sh.

31. 29 not 30

32. (comment or editorial or newspaper article).pt.

33. 31 not 32

34. limit 33 to english language

35. limit 34 to "qualitative (maximises specificity)"