An Automated Patient Bed Cleaner Using UV Rays

Coronavirus (COVID-19) is an infectious illness due to serious respiratory trouble. It is impacted numerous humans and has asserted the living expectancy of a greater number of persons from all over the planet. The maturation period of this virus, on typically about 5-6 days but it might also be up to 2 weeks. Throughout this period, the individual may not feel any indications but could still be transmissible. A person could develop this disease if he/ she inhales the virus while a diseased person/ virus carrier within close vicinity sneezes or coughs otherwise tapping an infected place in addition to afterward again his/ her eyes, nose or mouth. To prevent this, the region of the COVID-19 patient must be decontaminated with virucidal disinfectants, such as and 0.05% sodium hypochlorite (NaClO) and ethanol-based products (at least 70%) an optional technique used is UV light sterilization. Ultraviolet (UV) sterilization technology is used to help reduce micro-organisms that can remain on surfaces after basic sprinkling to the minimum amount. The proposed work has established an UV robot or UV bot to perform decontamination in an operating room or in-patients room. Three 19.3-watt UV lights are positioned in a 360-degree circle on the UV bot platform. It used an integrated system based on a microprocessor and a metal frame to aid in navigation in a fixed path to avoid barriers. In addition, a sanitizer dispenser is also included to clean the viral organisms, which is spread through the water droplets of the patient. © 2022 IEEE.

The association of COVID-19 incidence with temperature, humidity, and UV radiation - A global multi-city analysis.

BACKGROUND AND AIM: The associations between COVID-19 transmission and meteorological factors are scientifically debated. Several studies have been conducted worldwide, with inconsistent findings. However, often these studies had methodological issues, e.g., did not exclude important confounding factors, or had limited geographic or temporal resolution. Our aim was to quantify associations between temporal variations in COVID-19 incidence and meteorological variables globally. METHODS: We analysed data from 455 cities across 20 countries from 3 February to 31 October 2020. We used a time-series analysis that assumes a quasi-Poisson distribution of the cases and incorporates distributed lag non-linear modelling for the exposure associations at the city-level while considering effects of autocorrelation, long-term trends, and day of the week. The confounding by governmental measures was accounted for by incorporating the Oxford Governmental Stringency Index. The effects of daily mean air temperature, relative and absolute humidity, and UV radiation were estimated by applying a meta-regression of local estimates with multi-level random effects for location, country, and climatic zone. RESULTS: We found that air temperature and absolute humidity influenced the spread of COVID-19 over a lag period of 15 days. Pooling the estimates globally showed that overall low temperatures (7.5 °C compared to 17.0 °C) and low absolute humidity (6.0 g/m3 compared to 11.0 g/m3) were associated with higher COVID-19 incidence (RR temp =1.33 with 95%CI: 1.08; 1.64 and RR AH =1.33 with 95%CI: 1.12; 1.57). RH revealed no significant trend and for UV some evidence of a positive association was found. These results were robust to sensitivity analysis. However, the study results also emphasise the heterogeneity of these associations in different countries. CONCLUSION: Globally, our results suggest that comparatively low temperatures and low absolute humidity were associated with increased risks of COVID-19 incidence. However, this study underlines regional heterogeneity of weather-related effects on COVID-19 transmission.

Pollution free UV-C radiation to mitigate COVID-19 transmission.

The high rate of transmission of the COVID-19 virus has brought various types of disinfection techniques, for instance, hydrogen peroxide vaporization, microwave generating steam, UV radiation, and dry heating, etc. to prevent the further transmission of the virus. The chemical-based techniques are predominantly used for sanitization of hands, buildings, hospitals, etc. However, these chemicals may affect the health of humans and the environment in unexplored aspects. Furthermore, the UV lamp-based radiation sanitization technique had been applied but has not gained larger acceptability owing to its limitation to penetrate different materials. Therefore, the optical properties of materials are especially important for the utilization of UV light on such disinfection applications. The germicidal or microorganism inactivation application of UV-C has only been in-use in a closed chamber, due to its harmful effect on human skin and the eye. However, it is essential to optimize UV for its use in an open environment for a larger benefit to mitigate the virus spread. In view of this, far UV-C (222nm) based technology has emerged as a potential option for the sanitization in open areas and degradation of microorganisms present in aerosol during the working conditions. Hence, in the present review article, efforts have been made to evaluate the technical aspects of UV (under the different spectrum and wavelength ranges) and the control of COVID 19 virus spread in the atmosphere including the possibilities of the human body sanitization in working condition.

COVID-19 pandemic: environmental and social factors influencing the spread of SARS-CoV-2 in São Paulo, Brazil.

The new coronavirus SARS-CoV-2 has infected more than 14 million people worldwide so far. Brazil is currently the second leading country in number of cases of COVID-19, while São Paulo state accounts for 20% of total confirmed cases in Brazil. The aim of this study was to assess environmental and social factors influencing the spread of SARS-CoV-2 in the expanded metropolitan area of São Paulo, Brazil. Firstly, a spatial analysis was conducted to provide insights into the spread of COVID-19 within the expanded metropolitan area. Moreover, Spearman correlation test and sensitivity analysis were performed to assess social indicators and environmental conditions which possibly influence the incidence of COVID-19. Our results reveal that the spread of COVID-19 from the capital city São Paulo-its epicenter in Brazil-is directly associated with the availability of highways within the expanded metropolitan area of São Paulo. As for social aspects, COVID-19 infection rate was found to be both positively correlated with population density, and negatively correlated with social isolation rate, hence indicating that social distancing has been effective in reducing the COVID-19 transmission. Finally, COVID-19 infection rate was found to be inversely correlated with both temperature and UV radiation. Together with recent literature our study suggests that the UV radiation provided by sunlight might contribute to depletion of SARS-CoV-2 infectivity.

Watts-level ultraviolet-C LED integrated light sources for efficient surface and air sterilization

With the epidemic of the coronavirus disease (COVID-19) infection, AlGaN-based ultraviolet-C light emitting diodes (UVC-LEDs) have attracted widespread attention for their sterilization application. However, the sterilization characters of high power integrated light sources (ILSs) haven't been widely investigated before utilizing in public sanitary security. In this work, by integrating up to 195 UVC-LED chips, high power UVC-LED ILSs with a light output power (LOP) of 1.88 W were demonstrated. The UVC-LED ILSs were verified to have efficient and rapid sterilization capability, which have achieved more than 99.9% inactivation rate of several common pathogenic microorganisms within 1 s. In addition, the corresponding air sterilization module based on them was also demonstrated to kill more than 97% of Staphylococcus albus in the air of 20 m(3) confined room within 30 min. This work demonstrates excellent sterilization ability of UVC-LED ILSs with high LOP, revealing great potential of UVC-LEDs in sterilization applications in the future.

Exposure to solar UV radiation of Polish teenagers after the first COVID-19 lockdown in March-April 2020.

In Poland, schools were closed from March to June 2020 due to the COVID-19 epidemic. During the lockdown (March-April), everyone was advised to stay at home. From May, students were allowed to spend time outdoors. We examine their exposure to solar UV radiation during the period of virtual learning at schools (May-June), vacations (July-August) and the first month of typical learning (September). Primary and high school students aged 12-18 completed a questionnaire on the details of their outdoor activities and the weather at the exposure site. A total of 146 anonymous questionnaires were registered for the study. The survey responses provided input to a radiative transfer model to estimate erythemal and vitamin D doses obtained by teenagers during outdoor activities. The results from 48% of the questionnaires indicated that students' exposure exceeded 1 minimal erythema dose (MED) during the day. Corresponding doses of sun-synthesized vitamin D, in excess of 1000 international units (IU) and 2000 IU, were found in 77% and 66% of the surveys, respectively. Only 12% of the teenagers declared that they use sunscreen. The overexposure (> 1 MED) increased with age. It was found in 72% and 26% of surveys among the students aged 17-18 and 12-14, respectively. Teenagers seem to have tried to compensate for the lack of sunlight during the lockdown by engaging in outdoor activities permitted since May. While those activities could have improved their vitamin D levels, they also put them at a higher risk of developing erythema.

Device for Identifying the UV Emission Spectrum.

Nowadays, the disinfection of classrooms, shopping malls, and offices has become an important part of our lives. One of the most effective disinfection methods is ultraviolet (UV) radiation. To ensure the disinfection device has the required wavelength spectrum, we need to measure it with dedicated equipment. Thus, in this work, we present the development of a UV spectrum detector capable of identifying UV wavelength spectrums, with a wide range of probes and the ability to transmit data to a PC for later evaluation of the results. The device was developed with four UV sensors: one for UV-A, one for UV-B, one for UV-C, and one with a wide range of detection of UVA, with a built-in transimpedance amplifier. An Arduino Nano development board processes all the acquired data. We developed a custom light source containing seven UV LEDs with different central wavelengths to calibrate the device. For easy visualization of the results, custom PC software was developed in the Processing programming medium. For the two pieces of electronics-the UV detector and calibration device-3D-printed housings were created to be ergonomic for the end-user. From the price point of view, this device is affordable compared to what we can find on the market.

Numerical model of the irradiance field surrounding a UV disinfection robot.

Objective.New technologies, including robots comprising germ-killing UV lamps, are increasingly being used to decontaminate hospitals and prevent the spread of COVID-19 and other superbugs. Existing approaches for modelling the irradiance field surrounding mobile UV disinfection robots are limited by their inability to capture the physics of their bespoke geometrical configurations and do not account for reflections. The goal of this research was to extend current models to address these limitations and to subsequently verify these models using empirically collected data.Approach.Two distinct parametric models were developed to describe a multi-lamp robotic UV system and adapted to incorporate the effects of irradiance amplification from the device's reflectors. The first model was derived from electromagnetic wave theory while the second was derived from conservation of energy and diffusion methods. Both models were tuned using data from empirical testing of an existing UV robot, and then validated using an independent set of measurements from the same device.Results.For each parameter, predictions made using the conservation of energy method were found to closely approximate the empirical data, offering more accurate estimates of the 3D irradiance field than the electromagnetic wave theory model.Significance.The versatility of the proposed method ensures that it can be easily adapted to different embodiments, providing a systematic way for researchers to develop accurate numerical models of custom UV robots, which may be used to inform deployment and/or to improve the accuracy of virtual simulation.

Estimation of the SARS-CoV-2 Virus Inactivation Time Using Spectral Ultraviolet Radiation

Corona Virus Disease 19 pandemic (COVID-19) causes many deaths worldwide, and has enormous impacts on society and economy. The COVID-19 was caused by a new type of coronavirus (Severe Acute Respiratory Syndrome Cornonavirus 2;SARS-CoV-2), which has been found that these viruses can be effectively inactivated by ultraviolet (UV) radiation of 290315 nm. In this study, 90% inactivation time of the SARS-CoV-2 virus was analyzed using ground observation data from Brewer spectrophotometer at Yonsei University, Seoul and simulation data from UVSPEC for the period of 2015-2017 and 2020. Based on 12:00-13:00 noon time, the shortest virus inactivation time were estimated as 13.5 minutes in June and 4.8 minutes in July/August, respectively, under all sky and clear sky conditions. In the diurnal and seasonal variations, SARS-CoV-2 could be inactivated by 90% when exposed to UV radiation within 60 minutes from 10:00 to 14:00, for the period of spring to autumn. However, in winter season, the natural prevention effect was meaningless because the intensity of UV radiation weakened, and the time required for virus inactivation increased. The spread of infectious diseases such as COVID-19 is related to various and complex interactions of several variables, but the natural inactivation of viruses by UV radiation presented in this study, especially seasonal differences, need to be considered as major variables.

Uncovering the disposable face masks as vectors of metal ions (Pb(â ¡), Cd(â ¡), Sr(â ¡)) during the COVID-19 pandemic.

The demand for disposable face masks (DFMs) increased sharply in response to the COVID-19 pandemic. However, information regarding the underlying roles of the largely discarded DFMs in the environment is extremely lacking. This study focused on the pristine and UV-aged DFMs as vectors of metal ions (Pb(Ⅱ), Cd(Ⅱ), and Sr(Ⅱ)). Further, the aging mechanism of DFMs with UV radiation as well as the interaction mechanisms between DFMs and metal ions were investigated. Results revealed that the aging process would help to promote more metal ions adsorbed onto DFMs, which was mainly attributed to the presence of oxygen-containing groups on the aged DFMs. The adsorption affinity of pristine and aged DFMs for the metal ions followed Pb(Ⅱ) > Cd(Ⅱ) > Sr(Ⅱ), which was positively corrected with the electronegativity of the metals. Interestingly, we found that even if DFMs were not disrupted, DFMs had similar or even higher adsorption affinity for metals compared with other existing microplastics. Besides, regarding environmental factors, including salinity and solution pH played a crucial role in the adsorption processes, with greater adsorption capacities for pristine and aged DFMs at higher pH values and low salinity. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and density functional theory further confirmed that the pristine DFMs interacted with the metals mainly through electrostatic interaction, while electrostatic interaction and surface complexation jointly regulated the adsorption of the metals onto aged DFMs. Overall, these findings would help to evaluate environmental behaviors and risks of DFMs associated with metals.

Methods of Inactivation of Highly Pathogenic Viruses for Molecular, Serology or Vaccine Development Purposes.

The handling of highly pathogenic viruses, whether for diagnostic or research purposes, often requires an inactivation step. This article reviews available inactivation techniques published in peer-reviewed journals and their benefits and limitations in relation to the intended application. The bulk of highly pathogenic viruses are represented by enveloped RNA viruses belonging to the Togaviridae, Flaviviridae, Filoviridae, Arenaviridae, Hantaviridae, Peribunyaviridae, Phenuiviridae, Nairoviridae and Orthomyxoviridae families. Here, we summarize inactivation methods for these virus families that allow for subsequent molecular and serological analysis or vaccine development. The techniques identified here include: treatment with guanidium-based chaotropic salts, heat inactivation, photoactive compounds such as psoralens or 1.5-iodonaphtyl azide, detergents, fixing with aldehydes, UV-radiation, gamma irradiation, aromatic disulfides, beta-propiolacton and hydrogen peroxide. The combination of simple techniques such as heat or UV-radiation and detergents such as Tween-20, Triton X-100 or Sodium dodecyl sulfate are often sufficient for virus inactivation, but the efficiency may be affected by influencing factors including quantity of infectious particles, matrix constitution, pH, salt- and protein content. Residual infectivity of the inactivated virus could have disastrous consequences for both laboratory/healthcare personnel and patients. Therefore, the development of inactivation protocols requires careful considerations which we review here.

A Review on the Potential of Common Disinfection Processes for the Removal of Virus from Wastewater.

Due to the prevalence of the COVID-19 outbreak, as well as findings of SARS-CoV-2 RNA in wastewater and the possibility of viral transmission through wastewater, disinfection is required. As a consequence, based on prior investigations, this work initially employed the viral concentration detection technique, followed by the RT-qPCR assay, as the foundation for identifying the SARS-CoV-2 virus in wastewater. After that, the ability and efficacy of chlorine, ozone, and UV disinfection to inactivate the SARS-CoV-2 virus from wastewater were examined. Chlorine disinfection is the most extensively used disinfection technology due to its multiple advantages. With a chlorine dioxide disinfectant dose of 40 mg/L, the SARS-CoV virus is inactivated after 30 min of contact time. On the other hand, ozone is a powerful oxidizer and an effective microbicide that is employed as a disinfectant due to its positive characteristics. After 30 min of exposure to 1000 ppmv ozone, corona pseudoviruses are reduced by 99%. Another common method of disinfection is using ultraviolet radiation, which is usually 253.7 nm suitable for ultraviolet disinfection. At a dose of 1048 mJ/cm2, UVC radiation completely inactivates the SARS-CoV-2 virus. Finally, to evaluate disinfection performance and optimize disinfection strategies to prevent the spread of SARS-CoV-2, this study attempted to investigate the ability to remove and compare the effectiveness of each disinfectant to inactive the SARS-CoV-2 virus from wastewater, summarize studies, and provide future solutions due to the limited availability of integrated resources in this field and the spread of the SARS-CoV-2 virus worldwide.

Topical hypochlorous acid (HOCl) blocks inflammatory gene expression and tumorigenic progression in UV-exposed SKH-1 high risk mouse skin.

Hypochlorous acid (HOCl) is the active oxidizing principle underlying drinking water disinfection, also delivered by numerous skin disinfectants and released by standard swimming pool chemicals used on a global scale, a topic of particular relevance in the context of the ongoing COVID-19 pandemic. However, the cutaneous consequences of human exposure to HOCl remain largely unknown, posing a major public health concern. Here, for the first time, we have profiled the HOCl-induced stress response in reconstructed human epidermis and SKH-1 hairless mouse skin. In addition, we have investigated the molecular consequences of solar simulated ultraviolet (UV) radiation and HOCl combinations, a procedure mimicking co-exposure experienced for example by recreational swimmers exposed to both HOCl (pool disinfectant) and UV (solar radiation). First, gene expression elicited by acute topical HOCl exposure was profiled in organotypic human reconstructed epidermis. Next, co-exposure studies (combining topical HOCl and UV) performed in SKH-1 hairless mouse skin revealed that the HOCl-induced cutaneous stress response blocks redox and inflammatory gene expression elicited by subsequent acute UV exposure (Nos2, Ptgs2, Hmox1, Srxn1), a finding consistent with emerging clinical evidence in support of a therapeutic role of topical HOCl formulations for the suppression of inflammatory skin conditions (e.g. atopic dermatitis, psoriasis). Likewise, in AP-1 transgenic SKH-1 luciferase-reporter mice, topical HOCl suppressed UV-induced inflammatory signaling assessed by bioluminescent imaging and gene expression analysis. In the SKH-1 high-risk mouse model of UV-induced human keratinocytic skin cancer, topical HOCl blocked tumorigenic progression and inflammatory gene expression (Ptgs2, Il19, Tlr4), confirmed by immunohistochemical analysis including 3-chloro-tyrosine-epitopes. These data illuminate the molecular consequences of HOCl-exposure in cutaneous organotypic and murine models assessing inflammatory gene expression and modulation of UV-induced carcinogenesis. If translatable to human skin these observations provide novel insights on molecular consequences of chlorination stress relevant to environmental exposure and therapeutic intervention.

Emerging contaminants, SARS-COV-2 and wastewater treatment plants, new challenges to confront: A short review.

The current pandemic caused by SARS-CoV-2 has put public health at risk, being wastewater-based epidemiology (WBE) a potential tool in the detection, prevention, and treatment of present and possible future outbreaks, since this virus enters wastewater through various sources such as feces, vomit, and sputum. Thus, advanced technologies such as advanced oxidation processes (AOP), membrane technology (MT) are identified through a systematic literature review as an alternative option for the destruction and removal of emerging contaminants (drugs and personal care products) released mainly by infected patients. The objectives of this review are to know the implications that the new COVID-19 outbreak is generating and will generate in water compartments, as well as the new challenges faced by wastewater treatment plants due to the change in a load of contaminants and the solutions proposed based on the aforementioned technologies to be applied to preserve public health and the environment.

Performance study of a sterilization box using a combination of heat and ultraviolet light irradiation for the prevention of COVID-19.

SARS-CoV-2 virus and other pathogenic microbes are transmitted to the environment through contacting surfaces, which need to be sterilized for the prevention of COVID-19 and related diseases. In this study, a prototype of a cost-effective sterilization box is developed to disinfect small items. The box utilizes ultra violet (UV) radiation with heat. For performance assessment, two studies were performed. First, IgG (glycoprotein, a model protein similar to that of spike glycoprotein of SARS-COV-2) was incubated under UV and heat sterilization. An incubation with UV at 70 °C for 15 min was found to be effective in unfolding and aggregation of the protein. At optimized condition, the hydrodynamic size of the protein increased to ~171 nm from ~5 nm of the native protein. Similarly, the OD280 values also increased from 0.17 to 0.78 indicating the exposure of more aromatic moieties and unfolding of the protein. The unfolding and aggregation of the protein were further confirmed by the intrinsic fluorescence measurement and FTIR studies, showing a 70% increase in the ß-sheets and a 22% decrease in the α-helixes of the protein. The designed box was effective in damaging the protein's native structure indicating the effective inactivation of the SARS-COV-2. Furthermore, the incubation at 70 °C for 15 min inside the chamber resulted in 100% antibacterial efficacy for the clinically relevant E.coli bacteria as well as for bacteria collected from daily use items. It is the first detailed performance study on the efficacy of using UV irradiation and heat together for disinfection from virus and bacteria.

SARS-CoV-2 viability under different meteorological conditions, surfaces, fluids and transmission between animals.

Since the COVID-19 outbreak, researchers have tried to characterise the novel coronavirus SARS-CoV-2 to better understand the pathogenic mechanisms of the virus and prevent further dissemination. As a consequence, there has been a bloom in scientific research papers focused on the behaviour of the virus in different environmental contexts. Nevertheless, despite these efforts and due to its novelty, available information about this coronavirus is limited, as several research studies are still ongoing. This review aims to shed light on this issue. To that end, we have examined the scientific literature to date regarding the viability of SARS-CoV-2 on surfaces and fluids or under different environmental conditions (temperature, precipitation and UV radiation). We have also addressed the role of animals in the transmission of this coronavirus.

Sunlight ultraviolet radiation dose is negatively correlated with the percent positive of SARS-CoV-2 and four other common human coronaviruses in the U.S.

Human coronaviruses are RNA viruses that are sensitive to ultraviolet (UV) radiation. Sunlight contains UVA (320-400 nm), UVB (260-320 nm) and UVC (200-260 nm) action spectra. UVC can inactivate coronaviruses, including severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2). The incidence and mortality of coronavirus disease 2019 (COVID-19) are considered to be correlated with vitamin D levels. Vitamin D synthesis in human skin is closely related to exposure to UVB radiation. Therefore, the incidence and mortality of COVID-19 are also considered to be correlated with Vitamin D levels. In this study, Spearman and Kendall rank correlation analysis tests were used to analyze the correlation between the average percent positive of five human coronaviruses (SARS-CoV-2, CoVHKU1, CoVNL63, CoVOC43, and CoV229E) in the U.S. and the corresponding sunlight UV radiation dose The results indicated that the monthly average percent positive of four common coronaviruses was significantly negatively correlated with the sunlight UV radiation dose. The weekly percent positive of SARS-CoV-2 during April 17, 2020 to July 10, 2020 showed a significant negative correlation with the sunlight UV radiation dose in census regions 1 and 2 of the U.S. while no statistical significance in the other regions. Additionally, sunlight UV radiation also showed some negative effects with respect to the early SARS-CoV-2 transmission.

Ultraviolet Box: An Innovative In-house Use of Ultraviolet Irradiation for Conservation of Respirators in COVID-19 Pandemic.

AIM: To use ultraviolet (UV) radiations in an indigenous method for sterilization of respirators for reuse during COVID-19 outbreak. BACKGROUND: COVID-19 outbreak has infected more than 200 countries. In India, till now, more than 100,000 cases have been reported. Healthcare workers are at high risk of developing infections being in the frontline of taking care of COVDI-19 cases. The demands of personal protective equipment (PPE) are increasing, but the same is not matched with supply due to various reasons. In such scenarios, reusing respirators and face shields is an alternative. UV radiations have quick action and are able to preserve the quality of respirators. We have developed a UV box for surface sterilization of respirators with an intention to reuse. TECHNIQUE: A thermocol box was taken from the central drug store and was fitted with two UV tubes of 254 nm wavelength procured from local service center of water purifiers. The position of the two tubes was such that one was near the base while other was fixed at the top. An aluminum mesh frame was placed in the middle of the box to act as a platform. The roof of the box was converted into a lid. The effectiveness of assembly was tested using culture of Escherichia coli and Staphylococcus aureus. In addition, a biological indicator tube containing test strip with spores of Bacillus atrophaeus was also exposed to UV light for a predefined duration, which did not show any color change after incubation for 48 hours. CONCLUSION: Our prototype assembly with supported efficacy from microbiological tests is an option for use of UV light within available resources for disinfection and reuse of scarce supplies of personal protective equipment. CLINICAL SIGNIFICANCE: UV box can help in meeting the demand supply deficit for respirators, face shields, and goggles that are paramount for the protection of HCW. HOW TO CITE THIS ARTICLE: Kumar P, Chaudhry D, Parmar A, Tyagi D, BG Manjunath, Singh PK. Ultraviolet Box: An Innovative In-house Use of Ultraviolet Irradiation for Conservation of Respirators in COVID-19 Pandemic. Indian J Crit Care Med 2020;24(8):713-715.

SARS-CoV-2 infection: physiological and environmental gift factors at high altitude.

Abstract: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has emerged as a global pandemic. This viral disease primarily causes lung pneumonia and has a wide range of clinical manifestations. The severity of infection ranges from those who are asymptomatic or with mild symptoms which do not require hospital admission, to those who require ventilator support and eventually die, depending on immunity, age and other comorbidities existing with the patients. The present report is an attempt to study the effect of physiological and environmental factors existing at high altitudes (HA) with spread of SARS-CoV-2 infection. Analysis of existing data revealed that HA natives do possess certain physiological advantages such as (1) improved hypoxic ventilatory response, (2) higher concentration of oxygen carrying molecules, haemoglobin, (3) increased production of Vitamin D, due to intense solar radiation, (4) lower rates of comorbidities such as lung infections, obesity etc. and (5) most importantly reduced production of angiotensin converting enzyme 2, a carrier molecule for SARS-CoV-2 virus entry into the host cell; all of which can collectively account for improved tolerance to SARS-CoV-2 infection in HA natives. In addition, environmental factors at HA such as (6) dry and chilly winds, (7) low air density and (8) intense UV radiations may further inhibit viral growth and spread into the atmosphere. We thus conclude that, high altitude natives may posses physiological and environmental advantage over low landers in terms of reduced severity of SARS-CoV-2 infection and its limited spread. Graphic abstract: Gift factors associated with COVID-19 spread at high altitude.

COVID-19 fatalities, latitude, sunlight, and vitamin D.

BACKGROUND: Since Vitamin D is known to be vital in regulating the immune system, and sunlight UV radiation exposure on the skin produces Vitamin D and UV intensity is highest nearest the equator, a study was done to examine the correlation between the latitude and COVID-19 fatality rates for countries. METHODS: Eighty-eight countries were selected based on their likelihood of providing reliable data. Using death rates/million for each country from the "worldometer" website, a correlation analysis was done between death rates and a country's latitude. RESULTS: A highly significant, positive correlation was found between lower death rates and a country's proximity to the equator (Pearson r = 0.40 P < .0001, 2-tailed t test). The R squared of 0.16 means that 16% of the variation in death rates among nations is accounted for by the latitude of the country. Evidence is presented suggesting a direct correlation between sunlight exposure and reduced mortality. DISCUSSION: This study is the first to document a statistically significant correlation between a country's latitude and its COVID-19 mortality and is consistent with other research regarding latitude, Vitamin D deficiency, and COVID-19 fatalities. Limitations of this study are noted. CONCLUSIONS: Further research is needed to confirm the correlation between latitude and COVID-19 fatalities, and to determine the optimum amounts of safe sunlight exposure and/or vitamin D oral supplementation to reduce COVID-19 fatalities in populations that are at high risk for vitamin D deficiency.