The World Health Organization (WHO) advocated non-pharmaceutical Interventions (NPIs) to curtail the spread of COVID-19 globally while research efforts concentrated on other pharmaceutical interventions were ongoing. The rapidity with which the disease has been transmitted led to the development of several guidelines for infection control and preventive measures. These measures were adopted instantly and integrated into containment strategies to interrupt viral transmission by different governments 12.

The novel disease had no known curative therapy or vaccine at the inception of the pandemic therefore efforts were targeted towards clinical trials, non-pharmaceutical interventions, and vaccine development 3.

Non-pharmaceutical interventions are public health measures targeted at behavioral changes in a bid to interrupt the infection chain and transmission of the severe acute respiratory syndrome coronavirus (SARS-COV-2) in humans 4.

These non-pharmaceutical interventions include facial masking, lockdown measures, social distancing, hand hygiene, cough etiquettes, isolation, and quarantine measures among others 5. These interventions have proven to be effective in reducing the spread of COVID-19 disease among humans 6.

Although, most of these measures had a negative impact on societal functioning, human relations and the economy, their implementation was sacrosanct to curb the spread and flattening the curve of rising COVID-19 cases in various countries. 78.

Households have been identified as potential and probable settings for the transmission of COVID-19 diseases because several factors such as ventilation, shared spaces, and proximity might be challenging to control especially in clustered settings 9.

The slum settings used in this study refers to highly populated residential areas where housing is not in compliance with the original planning and building regulations 10.

The standard of living and hygiene situations in slums are usually not satisfactory and residents do not have access to most government amenities such as water supply. Factors which are important determinants of person-to-person transmission such as proximity, ventilation, social distancing are challenging to control in these settings 11.

In instituting a national lock down and restriction of movement, individuals in these settings are forced to stay at home together in this environment where living space constrain most facilities which are meant to be shared, and water supply is grossly inadequate.

This study aims to evaluate the challenges of implementing non-pharmaceutical interventions, assess adherence and associated factors, accessibility to prevention materials and identify requirements to the successful control of the spread of COVID-19 among individuals living in slums and crowded areas in Lagos state, Nigeria.

A semi-structured questionnaire was administered to an adult member of the selected households via a convenient sampling procedure. Individuals who gave consent to participate were recruited from 365 households and those who declined to participate and were excluded from the study.

Of the 365 participants, 357 completed the questionnaires and this was used for the analysis. Most of the respondents were aged 41-50 years (35%), males (62.2%), married (83.8%), self-employed (66.4%) and had secondary level (31.4%) of education (Table 1).

Almost all the respondents were aware of the COVID-19 pandemic and its recommended non pharmaceutical preventive measures (98.9%) however only 33.9% reported total adherence to the measures.

A good number of the respondents used facial mask coverings (77.3%) while approximately a quarter of the respondents used hand sanitizers (25.2%), practiced social distancing (22.1%), engaged in frequent washing of hands (28.3%) and avoided handshakes (23.2%).

Majority reported not adhering to recommended cough etiquette (82.6%), avoiding handshakes (77.6%), crowded places (86%), or touching of the face (85.2%), nose or mouth (Table 2).

An assessment of the living conditions of the respondents showed that majority shared kitchen (63.6%) and toilet facilities (64.4%) while a very high percentage do not have a space for isolation (93.9%) in the event of exposure to an infected person.

A total of 260 (72.8%) residents lived in a one room space and 66.7 % of the houses had only one window, with 31.9% sharing one room with four or more persons.

Over half of the respondents buy water (62.5%) or do not have constant supply of water (61.9%). Furthermore, 68.9% and 70.3% cannot afford to buy facemasks or hand sanitizers respectively (Table 3).

Major challenges identified as reasons for not adhering to non-pharmaceutical preventive measures were lack of water, lack of space or extra room for isolation, crowded living conditions, lack of funds, lack of prevention materials, poverty, forgetfulness, misconception about the pandemic and lack of palliatives among other reasons (Table 4).

Strategies such as the provision of free supply of prevention materials, institution of standard housing scheme, continuous sensitization, government supply of constant water to all homes, provisions of funds, provision of palliatives, engage monitoring team to enforce adherence were some of the suggested strategies to enhance total adherence among residents (Table 4).

Table 5 shows the results of factors associated with adherence to non-pharmaceutical COVID-19 preventive measures from a logistics regression analysis. After adjusting for all covariates, the ability to afford facemasks/hand sanitizers (aOR: 6.65; 95% CI: 3.81-11.61), living alone (aOR: 3.66; 95% CI: 1.27-10.56), and ability to buy water (aOR: 0.27; 95% CI: 0.14-0.50), were found to have an independent association with adherence to non-pharmaceutical intervention measures against COVID-19 and had greater odds of being associated with total adherence to the non-pharmaceutical COVID-19 preventive measures.

Factors such as sex (aOR:0.57; 95% CI:0.32-1.03), sharing of toilet facilities / kitchen space (aOR: 0.27; 95% CI:0.20-1.76), and the number of rooms in a house (aOR:1.07;95%CI:0.55-2.10) were found not to be associated with total or partial adherence to non-pharmaceutical intervention measures against COVID-19.

The government of various countries instituted non-pharmaceutical interventions at varying degrees to curb the spread and flatten the curve of rising infection rates while efforts at developing vaccines and effective drug therapy were ongoing 1213.

Spinelli and colleagues 14 have emphasized the need for continued implementation of non-pharmaceutical interventions even as vaccines are rolled out because these interventions will continue to play a critical role in suppressing SARS-CoV-2 virus transmission.

Al-Waiydy and Mohammed 15 reported the profound impact of the early implementation of these measures in curbing the spread of the virus. The prolonged implementation of the COVID-19 preventive measures impacts family, community, national, and global economic activities. The unprecedented nature of some restrictions and measures made adherence to these interventions quite challenging despite its potential benefits and has resulted in pandemic fatigue 16.

Human interaction is a major engine of transmission of the SARS-CoV-2 virus; the effectiveness and impact of these measures are dependent on societal cooperation and adherence 17. In this study societal cooperation and adherence was seen in less than half of the study population.

The use of face masks forms a barrier that prevents viral material between an individual who sneezes or coughs out droplets of contagious materials and the individual who inhales if both parties wear a face mask.

While social distancing measures are necessary to fill the gap between individuals because the SARS-CoV-2 virus is known to have a higher viral inoculum at closer distances to the infected persons. Adequate spacing between individuals also prevents expelled viral particles from having ample time to stay airborne and be inhaled before it settles on the ground and die off 1.

Various studies have investigated the effect of the individual non-pharmaceutical interventions, group of multiple interventions and the degree of adherence to these measures 18. Adhering to all the non-pharmaceutical measures is sacrosanct to minimize the chances of viral transmission.

Eikenberry et al., 2020 19 reported that wearing a face mask reduced daily deaths by 17% - 45% over a two-month period while Zhang et al.,2020 20 in China observed a 98.9% reduction in new infection cases because of the implementation of social distancing and epicenter lockdown.

Reports from developed countries shows varying degrees of adherence ranging from 49% in USA to 95% in Hong Kong and 100% in Vietnam to the use of face masks In this study, we found a relatively high adherence (77%) to the use of face mask, but a low adherence to the use of hand sanitizers (25.2%), social distancing (22.1%), washing of hands (28.3%) and observation of cough etiquettes (17.4%). Compared to reports from other countries it can be deduced that adherence pattern varies among regions and continents. Crane et al. 16 reported pandemic fatigue to other measures and a decrease in adherence except for face masks which improved to 88.6%. The finding may be similar to our findings which reported high adherence to face masks but very low adherence to other measures. However, we were unable to observe the change in adherence pattern over time because of the cross-sectional nature of our study.

The slum settings are known to be congested, crowded, and a deviation from the legal and organized plan. Transmission within the households contributed to the COVID-19 cases during the lockdown measures in the early period of the pandemic 21.

The crowded and close-knit nature of slum settings calls for attention regarding the implementation and adherence to these interventions. Cerami et al., 2021 22 have emphasized the role of households in viral transmission due to shared living space. This study has observed a wide range of challenges to adhere to these measures; however, the majority of the respondents identified lack of space, prevention materials, water, and funds among other reasons. The ability to afford facemasks/sanitizers and living alone have been observed to has a strong association with total adherence to the non-pharmaceutical interventions in this study.

A self-report determined total adherence in this study from the respondents, which might overestimate or underestimate the true picture hence an observed limitation of the study. Also, as explained in this study, total adherence is not a validated measure, but the idea was adopted from Crane et al. 16 It has given an insight into factors associated with total adherence. Most of the individuals in these settings buy water (62.5%) for daily use and frequent hand washing is a challenge. Furthermore, space for social distancing critical to curtailing the spread is in short supply in the slum setting studied. The respondents suggested that continuous sanitization, a standard housing scheme, constant water supply to homes and provision of palliatives will enhance adherence to the non-pharmaceutical interventions.

Iftimie et al., 2021 23 suggested that emergence of new variants and poor adherence to social distancing have contributed to the recurrent wave experienced in many countries. In addition, relaxation of restrictions and containment measure have also contributed to the pandemic waves 24. All these has re-emphasized the importance of the non-pharmaceutical interventions.

Lifestyle in the slums entails close human interactions due to the living conditions; therefore, environments with these characteristics should be given closer attention in monitoring / enforcing the practice of containment measures. Such communities should prioritize vaccination to prevent them from being a hub for circulation and recirculation of the virus.

Implementing non-pharmaceutical interventions in slum household settings can be challenging because of the living conditions. The lack of isolation space among almost all the respondents calls for concern. Inability to purchase prevention materials and sharing living space are significant factors influencing poor adherence to COVID-19 prevention strategies. There is a need to review the living conditions in the slums, institute some basic amenities, and prioritize vaccinating this cohort of individuals to avert the spread of infectious diseases like C OVID-19.

Ethical approval was obtained from the Institutional Review Board of the Nigerian Institute of Medical Research (IRB Approval Number 20-030).

This study was funded by the Nigerian Institute of Medical Research, Award Number NMG-CIF-26-0044.

Conceptualization: ESO. Data curation: ESO, SAO, OOO. Formal analysis: ESO, DAN. Funding acquisition: SBL, GTA. Methodology: ESO, GTA, SAO, OOO Project administration: ESO, GTA, SAO. Visualization: ESO, EOC. Writing - original draft: ESO, EOC. Writing - review & editing: DAN, EOC, SBL. All authors have read and approved of the final manuscript.