How Universal is the Use of Facemask During COVID-19 Pandemic? A Photo-Epidemiology Study from the Indian State of Kerala

Background & Objectives: Kerala state was the first to report COVID-19 case in India and was initially successful in curbing the spread of the virus. However, Kerala witnessed a surge of cases subsequently. This study aimed to estimate the prevalence of face mask use and social distancing in public places in Kerala. Methods: We did a cross-sectional photo-epidemiology study; wherein photographs of people in public places were taken across Kerala. Photos were analysed to determine the usage of mask, whether it was properly worn and the type of mask. Crowding was taken as a surrogate for social distancing. We compared mask use and crowding across district zones with low, medium and high COVID-19 burden. Results: We analysed 1445 photos capturing 4500 people with clear view of the face. Prevalence of mask use was 96% across the state. We found near complete mask use in the districts with high COVID-19 burden (99%) compared to districts with low (96%) and medium burden (95%). 20% of the people in public spaces either did not wear a mask or wore it improperly. Crowding was higher in high burden districts with a weak but positive correlation with case burden. Conclusion: Prevalence of face mask use was high across all districts in the Kerala State, but a considerable number of people were unprotected due to improper or non-usage of masks. Crowding in high burden districts indicate that inadequate social distancing could have contributed to increased cases, despite a high compliance to mask usage even in these districts. COVID-19 Pandemic? Photo-Ep-idemiology


Introduction
The state of Kerala (population 34 million) was the first to report the Corona Virus Disease 2019 (COVID- 19) case in India on January 30, 2020 in three medical students who returned from Wuhan, China [1]. Prompt quarantine measures effectively stopped transmission from these cases. The state government initiated a series of public health measures including lockdown, social distancing and mandatory wearing of facemasks [2,3]. The next wave of cases was reported subsequent to the return of nonresident Keralites from the gulf countries and Europe. This wave of infection was contained to double digits by May 2020, with no case of infection reported for nearly 5 days in the first week of May [4]. Universal face mask usage is considered as one of the key strategies to control the spread of COVID-19 in addition to hand washing, social distancing and avoiding closed spaces [5][6][7]. The role of mask was initially thought to be for source control; recommended for patients with upper respiratory symptoms to prevent spread of the virus from them [8]. Furthermore, asymptomatic and presymptomatic patients were also found to have viral shedding equivalent to symptomatic patients [9] with risk of transmission starting a few days before symptom onset and infectivity peaking at the time of symptom onset for the Severe acute respiratory syndrome coronavirus (SARS CoV-2) [10]. This mandated universal mask use particularly, in places with potency for community transmission and high risk of viral spread. In addition to preventing transmission from infected patients, masks protect the wearer from becoming infected by blocking viral particles from entering the nose and the mouth [11]. The type of mask and the technique of mask usage is key to ensuring effectiveness of universal masking [12].
Although the cloth mask is inferior to the surgical mask or the N95 masks in terms of virus filtering capacity, in a low transmissionrisk setting such as in public places, cloth masks are thought to be sufficient [13].
If infection happens despite mask usage, masks are thought to reduce the inoculum of the virus which may lead to asymptomatic or only mild infection [14]. The usage of masks has been commonly noted to be improper with inadequate coverage of the nose or sometimes with full exposure of the nose and mouth with the mask being pulled down to the neck which makes the mask usage ineffective [15]. This study aimed to estimate the prevalence of face mask usage amongst the public in Kerala during the COVID-19 pandemic using photo-epidemiology. Photo epidemiology is a simple and effective method to study the mask usage and social distancing. Mobile phone cameras can be used to capture photos in public setting with relatively less intrusion into privacy [11,16].
Specifically, the study tried to estimate the extent of mask use across the districts of Kerala, the urban-rural and gender difference variations. We counted faces per photo frame and used it as an indicator of crowding and social distancing. We also tried to correlate the COVID-19 case load at the district level with mask use and crowding. Further, two other authors independently analyzed a random sample of the selected photos to verify the recordings. Any discordance was settled by a referee. We divided the 14 districts into three zones based on the cumulative number of COVID-19 cases reported as of 28 August 2020 as follows: High zone (districts with total cases > 8000), Mid Zone (Cases 4000-8000) and Low Zone (Cases < 4000). We retrieved data on COVID-19 cases per million population for the districts from the official web portal of the government of Kerala [4]. In addition, we also analyzed the mask wearing practice as captured by the Closedcircuit television (CCTV) footage of shoppers from a shopping mall in one of the districts with a high COVID 19 burden number of cases. In this mall, COVID-19 protocols to ensure mask usage was supervised by security personnel at the entrance as well as inside the premises. We used this sample as a comparison group to study the mask usage in a supervised environment. Institutional Ethics Committee of Ananthapuri Hospitals and Research Institute, Thiruvananthapuram gave ethical clearance for the study.

Results
We took 1445 photos capturing 6208 people from all the 14 districts of Kerala. We included 4500 (73%) people in the analysis as the rest of the faces were not clear enough for analysis. Of them, 1841 (52%) were from the low zone, 1342 (30%) from the mid zone, and 1317 (29%) from the high zone. Half (50%) of the photos were taken from roadside, and around 56% were from urban areas.
Sample had 1026 (22.8%) women. Characteristics of the photo samples are presented in Table 1.

Mask Usage
Overall, we found very high mask use, with 96% people using masks, with no difference between men and women or between urban and rural areas. We found near complete mask use in the districts with high COVID-19 burden (99%) compared to districts with low (96%) and the medium burden (95%). There was statistically significant variation (p<0.001) between the zones.
Proper mask use was high in urban areas (86%) than in rural (82%); and high in the high burden zone (86%) compared to medium (85%) and low burden zones (82%). We found relatively lower proportion of people wearing masks properly in public places (84%) compared to hospital premises (95%). Of all the mask users, nine percent did not cover their nose (men 9%, women 7%).
This ranged from four percent in hospitals to nine percent in public places. Eight percent of mask users did not cover their nose and mouth (men 9%, women 3%). This ranged from four percent in hospital premises, to seven percent in other public places. There was significant difference in improper mask usage between zones with highest proportion in low zone followed by mid zone and high zone (p<0.05). The analysis of data on 1059 people (63% men) at the supervised mall showed 100% mask use. Almost all (99.4 %) wore their mask properly and majority of them (87%) were cloth mask.

Crowding and Social Distancing
The average number of faces per photo frame was 4.3 for the whole state, ranging from 2.5 per frame in Kollam to 7.9 in Wayanad. Overall, the number was significantly higher in photos from high zone (6) indicating crowding in public places in districts with high COVID-19 burden. Medium zone (5.1) and low zone

Discussion
This study is the first comprehensive report on the prevalence of face mask use in any Indian state during the COVID-19 pandemic.
A high prevalence of face mask usage (96%) was found across all districts in the Kerala State, but a considerable number of people (20%) were unprotected due to improper or non-usage of masks.
The districts in high zone with higher reported cases in-fact had greater compliance to face mask usage, likely indicating the possibility that the public were more cautious due to the higher infection spread in these districts as against a possibility of low mask usage as a contributory factor for higher disease spread. A survey of self-reported mask usage from 15 countries in April 2020 reported 76% mask usage in India, 76-91% in Asia and 16-34% in Europe and 50% in USA [16,17]

Financial Support
None.

Conflicts of Interest
None.