Public Health Impact of Paxlovid as Treatment for COVID-19, United States.

We evaluated the population-level benefits of expanding treatment with the antiviral drug Paxlovid (nirmatrelvir/ritonavir) in the United States for SARS-CoV-2 Omicron variant infections. Using a multiscale mathematical model, we found that treating 20% of symptomatic case-patients with Paxlovid over a period of 300 days beginning in January 2022 resulted in life and cost savings. In a low-transmission scenario (effective reproduction number of 1.2), this approach could avert 0.28 million (95% CI 0.03-0.59 million) hospitalizations and save US $56.95 billion (95% CI US $2.62-$122.63 billion). In a higher transmission scenario (effective reproduction number of 3), the benefits increase, potentially preventing 0.85 million (95% CI 0.36-1.38 million) hospitalizations and saving US $170.17 billion (95% CI US $60.49-$286.14 billion). Our findings suggest that timely and widespread use of Paxlovid could be an effective and economical approach to mitigate the effects of COVID-19.

Analysis of serological surveys of antibodies to SARS-CoV-2 in the United States to estimate parameters needed for transmission modeling and to evaluate and improve the accuracy of predictions.

Seroprevalence studies can estimate proportions of the population that have been infected or vaccinated, including infections that were not reported because of the lack of symptoms or testing. Based on information from studies in the United States from mid-summer 2020 through the end of 2021, we describe proportions of the population with antibodies to SARS-CoV-2 as functions of age and time. Slices through these surfaces at arbitrary times provide initial and target conditions for simulation modeling. They also provide the information needed to calculate age-specific forces of infection, attack rates, and - together with contact rates - age-specific probabilities of infection on contact between susceptible and infectious people. We modified the familiar Susceptible-Exposed-Infectious-Removed (SEIR) model to include features of the biology of COVID-19 that might affect transmission of SARS-CoV-2 and stratified by age and location. We consulted the primary literature or subject matter experts for contact rates and other parameter values. Using time-varying Oxford COVID-19 Government Response Tracker assessments of US state and DC efforts to mitigate the pandemic and compliance with non-pharmaceutical interventions (NPIs) from a YouGov survey fielded in the US during 2020, we estimate that the efficacy of social-distancing when possible and mask-wearing otherwise at reducing susceptibility or infectiousness was 31% during the fall of 2020. Initialized from seroprevalence among people having commercial laboratory tests for purposes other than SARS-CoV-2 infection assessments on 7 September 2020, our age- and location-stratified SEIR population model reproduces seroprevalence among members of the same population on 25 December 2020 quite well. Introducing vaccination mid-December 2020, first of healthcare and other essential workers, followed by older adults, people who were otherwise immunocompromised, and then progressively younger people, our metapopulation model reproduces seroprevalence among blood donors on 4 April 2021 less well, but we believe that the discrepancy is due to vaccinations being under-reported or blood donors being disproportionately vaccinated, if not both. As experimenting with reliable transmission models is the best way to assess the indirect effects of mitigation measures, we determined the impact of vaccination, conditional on NPIs. Results indicate that, during this period, vaccination substantially reduced infections, hospitalizations and deaths. This manuscript was submitted as part of a theme issue on "Modelling COVID-19 and Preparedness for Future Pandemics."

Social contact patterns during the COVID-19 pandemic in 21 European countries - evidence from a two-year study.

BACKGROUND: Most countries have enacted some restrictions to reduce social contacts to slow down disease transmission during the COVID-19 pandemic. For nearly two years, individuals likely also adopted new behaviours to avoid pathogen exposure based on personal circumstances. We aimed to understand the way in which different factors affect social contacts - a critical step to improving future pandemic responses. METHODS: The analysis was based on repeated cross-sectional contact survey data collected in a standardized international study from 21 European countries between March 2020 and March 2022. We calculated the mean daily contacts reported using a clustered bootstrap by country and by settings (at home, at work, or in other settings). Where data were available, contact rates during the study period were compared with rates recorded prior to the pandemic. We fitted censored individual-level generalized additive mixed models to examine the effects of various factors on the number of social contacts. RESULTS: The survey recorded 463,336 observations from 96,456 participants. In all countries where comparison data were available, contact rates over the previous two years were substantially lower than those seen prior to the pandemic (approximately from over 10 to < 5), predominantly due to fewer contacts outside the home. Government restrictions imposed immediate effect on contacts, and these effects lingered after the restrictions were lifted. Across countries, the relationships between national policy, individual perceptions, or personal circumstances determining contacts varied. CONCLUSIONS: Our study, coordinated at the regional level, provides important insights into the understanding of the factors associated with social contacts to support future infectious disease outbreak responses.

Analysis of metapopulation models of the transmission of SARS-CoV-2 in the United States.

During the COVID-19 pandemic, renewal equation estimates of time-varying effective reproduction numbers were useful to policymakers in evaluating the need for and impact of mitigation measures. Our objective here is to illustrate the utility of mechanistic expressions for the basic and effective (or intrinsic and realized) reproduction numbers, [Formula: see text] and related quantities derived from a Susceptible-Exposed-Infectious-Removed (SEIR) model including features of COVID-19 that might affect transmission of SARS-CoV-2, including asymptomatic, pre-symptomatic, and symptomatic infections, with which people may be hospitalized. Expressions from homogeneous host population models can be analyzed to determine the effort needed to reduce [Formula: see text] from [Formula: see text] to 1 and contributions of modeled mitigation measures. Our model is stratified by age, 0-4, 5-9, …, 75+ years, and location, the 50 states plus District of Columbia. Expressions from such heterogeneous host population models include subpopulation reproduction numbers, contributions from the above-mentioned infectious states, metapopulation numbers, subpopulation contributions, and equilibrium prevalence. While the population-immunity at which [Formula: see text] has captured the popular imagination, the metapopulation [Formula: see text] could be attained in an infinite number of ways even if only one intervention (e.g., vaccination) were capable of reducing [Formula: see text] However, gradients of expressions derived from heterogeneous host population models,[Formula: see text] can be evaluated to identify optimal allocations of limited resources among subpopulations. We illustrate the utility of such analytical results by simulating two hypothetical vaccination strategies, one uniform and other indicated by [Formula: see text] as well as the actual program estimated from one of the CDC's nationwide seroprevalence surveys conducted from mid-summer 2020 through the end of 2021.

Impact of respiratory aerosol size and number distribution on the relative importance of different routes in SARS-CoV-2 transmission.

Exploring the relative importance of different routes in SARS-CoV-2 transmission is crucial in infection prevention. However, even in the same environmental setting, the relative importance of different routes has varied in different studies. We hypothesize that respiratory aerosol size and number distribution might play a key role. In this study, size and number distribution of respiratory droplets emitted from breathing, talking, and coughing were identified from PubMed and Web of Science. The infection risk of SARS-CoV-2 via airborne, droplet, and fomite transmission routes was modeled in a household and a healthcare setting. The relative importance of three routes varied with different size distributions in both settings. Generally, the contribution of the airborne route increased with the volume percentage of respirable droplets emitted. And the increase of the total number of emitted droplets leads to an increase in the contribution of tdroplet route. In the healthcare setting, as the total number of emitted droplets increased from 110 to 4,973, the contribution of droplet route increased from 62.24% to 98.11%. Next, by considering the combination of breathing, coughing, and talking when the infected person was asymptomatic, the airborne route predominated over the droplet and contact routes. When the infected person had developed symptoms, that is, cough, the droplet route played a dominant role in SARS-CoV-2 transmission. In conclusion, risk analyses will be improved with improved sampling methods that enable characterization of viruses within respiratory droplets of different sizes.

Transmisión del SARS-CoV-2 en escolares durante el primer trimestre del curso 2021/2022 en la provincia de Albacete: incidencia e impacto de las nuevas variantes.

OBJECTIVE: The objective of this study was to know the evolution of the COVID-19 pandemic in the school setting, and the effect of the new variants on it. DESIGN: It is an observational longitudinal descriptive study during the first term of the academic year 21/22. SITE: Community health services. PARTICIPANTS: Preschool, elementary, secondary, and high school students. INTERVENTIONS: none. MAIN MEASUREMENTS: We calculated cumulative incidence stratified by grade, source of infection and follow-up period, percentage of vaccinated cases and correlation between cumulative incidence in schooled children per week and cumulative incidence in the general population. RESULTS: 1526 cases were reported, and the cumulative incidence was 3,17% and 0,48% in within-school acquired cases. 20,9% were vaccinated. During follow-up, there was an important change in incidence from weeks 49/21 on, at the time Omicron began to appear in Spain, with an increase in secondary cases, mostly high school students. We found a high correlation between general population and schooled children's cumulative incidence (R2 = 0,59). CONCLUSIONS: SARS-CoV-2 transmission in school settings has been affected by new circulating variants. Two propagation scenarios were identified, and they were like the community propagation pattern. This supports the hypothesis that school settings reflect the transmission in the community. Reinforcement of preventive measures and surveillance would have a positive effect on school settings.

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Delta Outbreak Among Fully Vaccinated Nursing Home Residents Likely Initiated by a Fully Vaccinated Staff Member - Connecticut, July-August 2021.

During July-August 2021, a coronavirus disease 2019 (COVID-19) outbreak involving 21 residents (all fully vaccinated) and 10 staff (9 fully vaccinated) occurred in a Connecticut nursing home. The outbreak was likely initiated by a fully vaccinated staff member and propagated by fully vaccinated persons. Prior COVID-19 was protective among vaccinated residents.

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Outbreak at a College With High Coronavirus Disease 2019 (COVID-19) Vaccination Coverage-Connecticut, August 2021-September 2021.

BACKGROUND: During August 2021-September 2021, a Connecticut college experienced a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Delta variant outbreak despite high (99%) vaccination coverage, indoor masking policies, and twice-weekly testing. The Connecticut Department of Public Health investigated characteristics associated with infection and phylogenetic relationships among cases. METHODS: A case was a SARS-CoV-2 infection diagnosed by a viral test during August 2021-September 2021 in a student. College staff provided enrollment and case information. An anonymous online student survey collected demographics, SARS-CoV-2 case and vaccination history, and activities preceding the outbreak. Multivariate logistic regression identified characteristics associated with infection. Phylogenetic analyses compared 115 student viral genome sequences with contemporaneous community genomes. RESULTS: Overall, 199 of 1788 students (11%) had laboratory-confirmed SARS-CoV-2 infection; most were fully vaccinated (194 of 199, 97%). Attack rates were highest among sophomores (72 of 414, 17%) and unvaccinated students (5 of 18, 28%). Attending in-person classes with an infectious student was not associated with infection (adjusted odds ratio [aOR], 1.0; 95% confidence interval [CI], .5-2.2). Compared with uninfected students, infected students were more likely to be sophomores (aOR, 3.3; 95% CI, 1.1-10.7), attend social gatherings before the outbreak (aOR, 2.8; 95% CI, 1.3-6.4), and complete a vaccine series ≥180 days prior (aOR, 5.5; 95% CI, 1.8-16.2). Phylogenetic analyses suggested a common viral source for most cases. CONCLUSIONS: SARS-CoV-2 infection in this highly vaccinated college population was associated with unmasked off-campus social gatherings, not in-person classes. Students should stay up to date on vaccination to reduce infection.

Universal Use of N95 Respirators in Healthcare Settings When Community Coronavirus Disease 2019 Rates Are High.

The Centers for Disease Control and Prevention recommends N95 respirators for all providers who see patients with possible or confirmed coronavirus disease 2019 (COVID-19). We suggest that N95 respirators may be just as important for the care of patients without suspected COVID-19 when community incidence rates are high. This is because severe acute respiratory syndrome coronavirus 2 is most contagious before symptom onset. Ironically, by the time patients are sick enough to be admitted to the hospital with COVID-19, they tend to be less contagious. The greatest threat of transmission in healthcare facilities may therefore be patients and healthcare workers with early occult infection. N95 respirators' superior fit and filtration provide superior exposure protection for healthcare providers seeing patients with early undiagnosed infection and superior source control to protect patients from healthcare workers with early undiagnosed infection. The probability of occult infection in patients and healthcare workers is greatest when community incidence rates are high. Universal use of N95 respirators may help decrease nosocomial transmission at such times.

Mobile PCR-based surveillance for SARS-CoV-2 to reduce visiting restrictions in nursing homes during the COVID-19 pandemic: a pilot study.

PURPOSE: Residents in nursing homes for the elderly (NH) are at high risk for death from COVID-19. We investigated whether repeated non-mandatory RT-PCR SARS-CoV-2 surveillance of NH staff and visitors reduces COVID-19 incidence rates in NH residents and allows to reduce visiting restrictions. METHODS: This pilot study at the beginning of the COVID-19 pandemic compared a surveillance approach of regular, twice-weekly voluntary PCR testing of health-care workers (HCW) and visitors in interventional NH (INH) with a setting without regular testing in control NH (CNH). Residents were not tested routinely within this study. Testing was performed in a mobile testing site with same-day result reporting. SARS-CoV-2 incidence among residents in both INH and CNH was the primary endpoint; secondary endpoints being SARS-CoV-2 infection among visitors and HCW in INH. RESULTS: Two INH and two CNH participated between October and December, 2020. At INH1, 787 tests of HCW and 350 tests of visitors were performed, accounting for 18.1% (n = 1930) of visits. At INH2, 78 tests of HCW and 372 tests of visitors were done, i.e., 30.5% (n = 1220) of visits. At the two INH 23 HCW and three visitors tested positive for SARS-CoV-2. COVID-19 outbreaks occurred among residents in INH1 (identified through study testing) and in CNH1. Utilization of voluntary testing was low. CONCLUSION: In a real-world setting without available rapid testing, voluntary RT-PCR SARS-CoV-2 testing of HCW and visitors does not prevent COVID-19 outbreaks in NH. Complete, non-selective testing for these groups should be instituted before visiting restrictions can be reduced. TRIAL REGISTRATION: The study has been registered at ClinicalTrials.gov with the identifier: NCT04933981.

Clinical-pathological features in placentas of pregnancies with SARS-CoV-2 infection and adverse outcome: case series with and without congenital transmission.

OBJECTIVE: To correlate clinical outcomes to pathology in SARS-CoV-2 infected placentas in stillborn and live-born infants presenting with fetal distress. DESIGN: Retrospective, observational. SETTING: Nationwide. POPULATION: Five stillborn and nine live-born infants from 13 pregnant women infected with SARS-CoV-2 seeking care at seven different maternity units in Sweden. METHODS: Clinical outcomes and placental pathology were studied in 14 cases (one twin pregnancy) of maternal SARS-CoV-2 infection with impaired fetal outcome. Outcomes were correlated to placental pathology in order to investigate the impact of virus-related pathology on the villous capillary endothelium, trophoblast and other cells. MAIN OUTCOME MEASURES: Maternal and fetal clinical outcomes and placental pathology in stillborn and live-born infants. RESULTS: Reduced fetal movements were reported (77%) and time from onset of maternal COVID-19 symptoms to signs of fetal distress among live-born infants was 6 (3-12) days and to diagnosis of stillbirth 11 (2-25) days. Two of the live-born infants died during the postnatal period. Signs of fetal distress led to emergency caesarean section in all live-born infants with umbilical cord blood gases and low Apgar scores confirming intrauterine hypoxia. Five stillborn and one live-born neonate had confirmed congenital transmission. Massive perivillous fibrinoid deposition, intervillositis and trophoblast necrosis were associated with SARS-CoV-2 placental infection and congenital transmission. CONCLUSIONS: SARS-CoV-2 can cause rapid placental dysfunction with subsequent acute fetal hypoxia leading to intrauterine fetal compromise. Associated placental pathology included massive perivillous fibrinoid deposition, intervillositis and trophoblast degeneration.

COVID-19 in the Czech Republic 2020 and 2021: comparative analysis of probable work-related transmission of the coronavirus SARS-CoV-2.

OBJECTIVES: The aim of the analysis was to determine the probable places of coronavirus transmission in association with the work and compare the situation between 2020 and 2021. METHODS: The work analysed data from the Information System of Infectious Diseases managed by the Institute of Health Information and Statistics of the Czech Republic in the period from March 2020 - December 2021. RESULTS: 2,483,219 COVID-19 cases were officially confirmed (732,202 during 2020 and 1,338,790 in 2021), from them 140,368 (6%) represented work-related disease, 520,830 cases (21%) work-related contact, and 1,822,021 (73%) out-of-work contact. There were identified 13 occupations with the highest incidence of COVID-19 in the observed period (458,341 cases), in descending order - clerk, machinist, teacher, craftsman, worker/agency worker, driver, sales worker/cashier, warehouse worker/expediter, nurse, manager, food worker, paramedic, and social worker. Comparing 2020 and 2021, there was a difference in the ranking of occupations by incidence of disease. In 2021, the risk of infection acquiring increased for the occupations clerk, machinist, craftsman, worker/agency worker, manager, and food worker, while it decreased for the health professions (nurse, other paramedic, physician) and for social worker; 5,514 cases of COVID-19 were recognized as an occupational disease in 2020 and 2021, from them 5,483 cases (99.4%) in the health and social care economic activity sector. CONCLUSION: The available data show probable exposures to an infectious agent (without proof of specific contact with the source of the infection), of which 27% cases of COVID-19 are related to work (cases of work-related disease and work-related contact represented together the closest relationship to work). Different relevant anti-epidemic measures in the workplace have considerable practical importance for epidemic control. The use of personal protection of the mouth and nose with respirators/muffs is essential to reduce the risk of airborne transmission.

SARS-CoV-2 cluster among security guards, Chennai, Tamil Nadu, India, June-July 2020.

Congregate work settings are at increased risk for SARS-CoV-2 transmission and predispose to super spreader events. We investigated a COVID-19 outbreak among security guards to identify the risk factors and propose recommendations. We defined a COVID-19 case as a laboratory-confirmed reverse transcription polymerase chain reaction-positive case. We traced the contacts actively and described the cases by time, place, and person. We conducted a case-control study and collected data on potential exposures. We identified 20 (27%) COVID-19 cases among 75 security guards. Among the cases, 17 (85%) were male and 12 (60%) were symptomatic. We recruited all the 20 COVID-19-confirmed cases and 55 COVID-19-negative controls for the case-control study. SARS-CoV-2 infection was higher among those had high-risk exposure (60%, [12/20]) than who did not (16%, [9/55], adjusted odds ratio = 5.9, 95% confidence interval = 1.6-22.1). Having had high-risk exposure with COVID-19 cases led to COVID-19 outbreak among the security guards. We recommended avoiding the activities predisposed to high-risk exposure.

Decreasing High-risk Exposures for Healthcare Workers Through Universal Masking and Universal Severe Acute Respiratory Syndrome Coronavirus 2 Testing on Entry to a Tertiary Care Facility.

We describe the impact of universal masking and universal testing at admission on high-risk exposures to severe acute respiratory syndrome coronavirus 2 for healthcare workers. Universal masking decreased the rate of high-risk exposures per patient-day by 68%, and universal testing further decreased those exposures by 77%.

Reconsidering Assumptions of Adolescent and Young Adult Severe Acute Respiratory Syndrome Coronavirus 2 Transmission Dynamics.

Evidence regarding the important role of adolescents and young adults (AYA) in accelerating and sustaining coronavirus disease 2019 (COVID-19) outbreaks is growing. Furthermore, data suggest that 2 known factors that contribute to high severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmissibility-presymptomatic transmission and asymptomatic case presentations-may be amplified in AYA. However, AYA have not been prioritized as a key population in the public health response to the COVID-19 pandemic. Policy decisions that limit public health attention to AYA and are driven by the assumption of insignificant forward transmission from AYA pose a risk of inadvertent reinvigoration of local transmission dynamics. In this viewpoint, we highlight evidence regarding the increased potential of AYA to transmit SARS-CoV-2 that, to date, has received little attention, discuss adolescent and young adult-specific considerations for future COVID-19 control measures, and provide applied programmatic suggestions.

Possible Human-to-Dog Transmission of SARS-CoV-2, Italy, 2020.

We detected severe acute respiratory syndrome coronavirus 2 in an otherwise healthy poodle living with 4 family members who had coronavirus disease. We observed antibodies in serum samples taken from the dog, indicating seroconversion. Full-length genome sequencing showed that the canine and human viruses were identical, suggesting human-to-animal transmission.

Impact of joint management of a COVID-19 mother and her newborn on the virus transmission: a case report.

BACKGROUND: Since last year, COVID-19, the disease caused by the novel Sars-Cov-2 virus, has been globally spread to all the world. COVID-19 infection among pregnant women has been described. However, transplacental transmission of Sars-Cov-2 virus from infected mother to the newborn is not yet established. The appropriate management of infants born to mothers with confirmed or suspected COVID-19 and the start of early breastfeeding are being debated. CASE PRESENTATION: We report a case of the joint management of a healthy neonate with his mother tested positive for Covid-19 before the delivery and throughout neonatal follow-up. The infection transmission from the mother to her baby is not described, even after a long period of contact between them and breastfeeding. CONCLUSION: It may consider an appropriate practice to keep mother and her newborn infant together in order to facilitate their contact and to encourage breastfeeding, although integration with infection prevention measures is needed.

Assessment of CO2 and aerosol (PM2.5, PM10, UFP) concentrations during the reopening of schools in the COVID-19 pandemic: The case of a metropolitan area in Central-Southern Spain.

Public health authorities have been paramount in guaranteeing that adequate fresh air ventilation is promoted in classrooms to avoid SARS-CoV-2 transmission in educational environments. In this work it was aimed to assess ventilation conditions (carbon dioxide, CO2) and suspended particulate matter (PM2.5, PM10 and UFP) levels in 19 classrooms - including preschool, primary and secondary education - located in the metropolitan area of Ciudad Real, Central-Southern Spain, during the school's reopening (from September 30th until October 27th, 2020) after about 7 months of lockdown due to COVID-19 pandemic. The classrooms that presented the worst indoor environmental conditions, according to the highest peak of concentration obtained, were particularly explored to identify the possible influencing factors and respective opportunities for improvement. Briefly, findings suggested that although ventilation promoted through opening windows and doors according to official recommendations is guaranteeing adequate ventilation conditions in most of the studied classrooms, thus minimizing the risk of SARS-CoV-2 airborne transmission, a total of 5 (26%) surveyed classrooms were found to exceed the recommended CO2 concentration limit value (700 ppm). In general, preschool rooms were the educational environments that registered better ventilation conditions, while secondary classrooms exhibited the highest peak and average CO2 concentrations. In turn, for PM2.5, PM10 and UFP, the concentrations assessed in preschools were, on average about 2-fold greater than the levels obtained in both primary and secondary classrooms. In fact, the indoor PM2.5 and PM10 concentrations substantially exceeded the recommended limits of 8hr-exposure, established by WHO, in 63% and 32% of the surveyed classrooms, respectively. Overall, it is expected that the findings presented in this study will assist the establishment of evidence-based measures (namely based on ensuring proper ventilation rates and air filtration) to mitigate preventable environmental harm in public school buildings, mainly at local and national levels.

CO2 concentration monitoring inside educational buildings as a strategic tool to reduce the risk of Sars-CoV-2 airborne transmission.

In order to avoid SARS-CoV-2 transmission inside educational buildings and promote the safe reopening of schools, the Italian Government, in line with the other European countries and in accordance with the WHO recommendations, adopted a contingency plan including actions able to guarantee adequate air ventilation in classrooms. Therefore, in this pilot study, a surveillance activity based on the real-time monitoring of CO2 levels as a proxy of SARS-CoV-2 transmission risk, was conducted inside 9 schools (11 classrooms) located in Apulia Region (South of Italy) during the reopening of schools after the lockdown due to COVID-19 pandemic. More specifically, monitoring activities and data treatment were conducted to evaluate the initial scenario inside the classrooms (first stage of evaluation) and the potential improvements obtained by applying a detailed operating protocol of air ventilation based on specific actions and the simultaneous real time visualization of CO2 levels by non-dispersive infrared (NDIR) sensors (second stage of evaluation). Although, during the first evaluation stage, air ventilation through the opening of windows and doors was guaranteed, 6 (54%) classrooms showed mean values of CO2 higher than 1000 ppm and all classrooms exceeded the recommended CO2 concentration limit value of 700 ppm. The development and implementation of tailored ventilation protocol including the real time visualization of CO2 levels allowed to depict better scenariosAn overall improvement of CO2 levels was indeed registered for all classrooms where teachers were compliant and helpful in the management of the air ventilation strategy. Therefore, this study reports the first evidence-based measures demonstrating that, with the exception of few environments affected by structural limits, the real-time visualization and monitoring of CO2 concentrations allowes effective air exchanges to be implemented and contributes to prevent SARS-CoV-2 transmission. Moreover, on the basis of the monitoring outcomes and in order to ensure adequate air ventilation in educational buildings, a 4 level-risk classification including specific corrective actions for each level was provided.

Association between ambient air pollutants and meteorological factors with SARS-CoV-2 transmission and mortality in India: an exploratory study.

BACKGROUND: The Coronavirus disease 2019 (COVID-19) pandemic poses a serious public health concern worldwide. Certain regions of the globe were severely affected in terms of prevalence and mortality than other. Although the cause for this pattern is not clearly understood, lessons learned from previous epidemics and emerging evidences suggest the major role of ecological factors like ambient air pollutants (AAP) and meteorological parameters in increased COVID-19 incidence. The present study aimed to understand the impact of these factors on SARS-CoV-2 transmission and their associated mortality in major cities of India. METHODS: This study used secondary AAP, meteorological and COVID-19 data from official websites for the period January-November 2020, which were divided into Pre-lockdown (January-March 2020), Phase I (April to June 2020) and Phase II (July to November 2020) in India. After comprehensive screening, five major cities that includes 48 CPCB monitoring stations collecting daily data of ambient temperature, particulate matter PM2.5 and 10 were analysed. Spearman and Kendall's rank correlation test was performed to understand the association between SARS-CoV-2 transmission and AAP and, meteorological variables. Similarly, case fatality rate (CFR) was determined to compute the correlation between AAP and COVID-19 related morality. RESULTS: The level of air pollutants in major cities were significantly reduced during Phase I compared to Pre-lock down and increased upon Phase II in all the cities. During the Phase II in Delhi, the strong significant positive correlation was observed between the AAP and SARS-CoV-2 transmission. However, in Bengaluru, Hyderabad, Kolkata and Mumbai AAP levels were moderate and no correlation was noticed. The relation between AT and SARS-CoV-2 transmission was inconclusive as both positive and negative correlation observed. In addition, Delhi and Kolkata showed a positive association between long-term exposure to the AAP and COVID-19 CFR. CONCLUSION: Our findings support the hypothesis that the particulate matter upon exceeding the satisfactory level serves as an important cofactor in increasing the risk of SARS-CoV-2 transmission and related mortality. These findings would help public health experts to understand the SARS-CoV-2 transmission against ecological variables in India and provides supporting evidence to healthcare policymakers and government agencies for formulating strategies to combat the COVID-19.