Are City Features Related to Obesity in Preschool Children? Evidence from Latin America

## **Effectiveness of Pharmaceutical and Non-Pharmaceutical Interventions Against Airborne Transmission: Computational Modeling Using CARA**

**Luis Aleixo1,2, André Henriques1, Gabriella Azzopardi1, James Devine1, Julian Tang3, Marco Andreini1 , Markus Rognlien4, Nicola Tarocco1, Nicolas Mounet1, Olivia Keiser5, and Philip Elson1**

<sup>1</sup> CERN (European Organization for Nuclear Research), Geneva, Switzerland,

<sup>2</sup> IST (Instituto Superior Técnico, University of Lisbon), Lisbon, Portugal,

<sup>3</sup> Respiratory Sciences, University of Leicester, Leicester, UK,

<sup>4</sup> NTNU (Norwegian University of Science and Technology), Torgarden, Norway,

<sup>5</sup> Institute of Global Health, University of Geneva, Geneva, Switzerland

The COVID-19 pandemic has highlighted the need for a proper risk assessment of respiratory pathogens in indoor settings. We aimed to develop a COVID Airborne Risk Assessment (CARA) tool, to assess the potential exposure of airborne SARS-CoV-2 viruses in indoor settings. The tool enables decision-makers to assess the risk of exposure to the virus, comparing several pharmaceutical and non-pharmaceutical interventions. The CARA model exhibits five main aspects: 1) the emission rate of viruses coming from the infected host(s), which is a result of the respiratory activity combined with the possible use of masks; 2) the viral removal rate resulting from ventilation or air filtration, viability decay, and settlement; 3) the viral concentration profile over time resulting from the balance of the two previous quantities; 4) the accumulated viral dose absorbed by an exposed host, deposited in the respiratory tract; and 5) the probability of infection (transmission) resulting from such a dose, including epidemiological, virological, and immunological parameters. The use of masks provides a five-fold reduction in emissions. Many settings rely on natural ventilation strategies, which are very effective in decreasing the concentration of virions, and in combination with masks, yield up to a 12-fold decrease in cumulative dose. Vaccination is an effective measure against hospitalization; however, its effectiveness against transmission is not optimal; hence, non-pharmaceutical interventions (ventilation, filtration, masks) should be actively supported. Vaccine effectiveness will also be limited by the emergence of new variants, whereas non-pharmaceutical interventions are effective independently of the variant. Therefore, measures that reduce the viral density in the air should be actively supported and included early in the risk-assessment process. Vaccination and host immunity are very important protective measures; however, non-pharmaceutical interventions seem to be more effective in preventing transmission. CARA allows for such a quick and accurate assessment of various indoor settings to assess the effectiveness of several (combined) measures. In a post-COVID era, we will face a new paradigm with the inclusion of this novel occupational hazard, using tools such as CARA to endorse healthy buildings and protect their occupants against respiratory infections.

Architecture and Technology


Efficiency of Pharmaceutical and Non-Pharmaceutical Interventions

Baseline scenario: Regular working day, room volume of 160 m3, winter season (cold and dry), 20 occupants, 1 is infected.

1. Tang J W, et al. Covid-19 has redefined airborne transmission, *BMJ 2021; 373 :n913*, doi:10.1136/bmj.n913


#### Authors

Luis Aleixo1,2, Andre Henriques1, Gabriella Azzopardi1, James Devine1, Julian Tang3, Marco Andreini1, Markus Rognlien4, Nicola Tarocco1, Nicolas Mounet1, Olivia Keiser5, and Philip Elson1

<sup>1</sup> CERN (European Organization for Nuclear Research), Geneva, Switzerland,

<sup>2</sup> IST (Instituto Superior Técnico, University of Lisbon), Lisbon, Portugal,

3 Respiratory Sciences, University of Leicester, Leicester, UK,

4 NTNU (Norwegian University of Science and Technology), Torgarden, Norway,

5 Institute of Global Health, University of Geneva, Geneva, Switzerland

#### Airborne Transmission of SARS-CoV-2


#### What is CARA?

