Frequent recovery of influenza A but not influenza B virus RNA in aerosols in pediatric patient rooms

Air quality of health facilities in Spain

The present study examines indoor air pollution in health facilities, focusing on compounds from various sources, such as industrial products, healthcare activities and building materials. It assesses chemical and microbiological concentrations in two public hospitals, two public healthcare centres, and one public health laboratory in Spain. Measurements included indoor air quality, microbiological contaminants, ambient parameters and non-target analysis across ten different locations. Outdoor air quality was also assessed in the surroundings of the hospitals. The results showed that around 350 substances were tentatively identified at a high confidence level, with over 50 % of compounds classified as of high toxicological risk. Three indoor and 26 outdoor compounds were fully confirmed with standards. These confirmed substances were linked to medical, industrial and agricultural activities. Indoor Air Quality (IAQ) results revealed that CO, CO2, formaldehyde (HCHO), O3 and total volatile organic compounds (TVOCs) showed average values above the recommended guideline levels in at least one of the evaluated locations. Moreover, maximum concentrations detected for CO, HCHO, O3 and TVOCs in hospitals surpassed those previously reported in the literature. SARS-CoV-2 was detected in three air environments, corresponding to COVID-19 patient areas. Fungi and bacteria concentrations were acceptable in all assessed locations, identifying different fungi genera, such as Penicillium, Cladosporium, Aspergillus, Alternaria and Botrytis.

Block the Spread: Barriers to Transmission of Influenza Viruses

Respiratory viruses, such as influenza viruses, cause significant morbidity and mortality worldwide through seasonal epidemics and sporadic pandemics. Influenza viruses transmit through multiple modes including contact (either direct or through a contaminated surface) and inhalation of expelled aerosols. Successful human to human transmission requires an infected donor who expels virus into the environment, a susceptible recipient, and persistence of the expelled virus within the environment. The relative efficiency of each mode can be altered by viral features, environmental parameters, donor and recipient host characteristics, and viral persistence. Interventions to mitigate transmission of influenza viruses can target any of these factors. In this review, we discuss many aspects of influenza virus transmission, including the systems to study it, as well as the impact of natural barriers and various nonpharmaceutical and pharmaceutical interventions.

SARS-CoV-2 and other airborne respiratory viruses in outdoor aerosols in three Swiss cities before and during the first wave of the COVID-19 pandemic

Caused by the SARS-CoV-2 virus, Coronavirus disease 2019 (COVID-19) has been affecting the world since the end of 2019. While virus-laden particles have been commonly detected and studied in the aerosol samples from indoor healthcare settings, studies are scarce on air surveillance of the virus in outdoor non-healthcare environments, including the correlations between SARS-CoV-2 and other respiratory viruses, between viruses and environmental factors, and between viruses and human behavior changes due to the public health measures against COVID-19. Therefore, in this study, we collected airborne particulate matter (PM) samples from November 2019 to April 2020 in Bern, Lugano, and Zurich. Among 14 detected viruses, influenza A, HCoV-NL63, HCoV-HKU1, and HCoV-229E were abundant in air. SARS-CoV-2 and enterovirus were moderately common, while the remaining viruses occurred only in low concentrations. SARS-CoV-2 was detected in PM₁₀ (PM below 10 µm) samples of Bern and Zurich, and PM_2.5 (PM below 2.5 µm) samples of Bern which exhibited a concentration positively correlated with the local COVID-19 case number. The concentration was also correlated with the concentration of enterovirus which raised the concern of coinfection. The estimated COVID-19 infection risks of an hour exposure at these two sites were generally low but still cannot be neglected. Our study demonstrated the potential functionality of outdoor air surveillance of airborne respiratory viruses, especially at transportation hubs and traffic arteries.

Particle sizes of infectious aerosols: implications for infection control

The global pandemic of COVID-19 has been associated with infections and deaths among health-care workers. This Viewpoint of infectious aerosols is intended to inform appropriate infection control measures to protect health-care workers. Studies of cough aerosols and of exhaled breath from patients with various respiratory infections have shown striking similarities in aerosol size distributions, with a predominance of pathogens in small particles (<5 μm). These are immediately respirable, suggesting the need for personal respiratory protection (respirators) for individuals in close proximity to patients with potentially virulent pathogens. There is no evidence that some pathogens are carried only in large droplets. Surgical masks might offer some respiratory protection from inhalation of infectious aerosols, but not as much as respirators. However, surgical masks worn by patients reduce exposures to infectious aerosols to health-care workers and other individuals. The variability of infectious aerosol production, with some so-called super-emitters producing much higher amounts of infectious aerosol than most, might help to explain the epidemiology of super-spreading. Airborne infection control measures are indicated for potentially lethal respiratory pathogens such as severe acute respiratory syndrome coronavirus 2.

Breathing Is Enough: For the Spread of Influenza Virus and SARS-CoV-2 by Breathing Only

Background: The transmission of respiratory viruses such as influenza and corona viruses from one person to another is still not fully understood. Methods: A literature search showed that there is a strong scientific rationale and evidence that viruses are very efficiently spread through aerosols by the patient's breathing only. It is not necessary for the patient to cough or sneeze. Results: The exhaled aerosol particles are generated by normal breathing in the deep lung through reopening of collapsed small airways during inspiration. These mucus/surfactant aerosols (size range between 0.2 and 0.6 μm) can transport viruses out of the lungs of patients and be present in the room air for hours. Conclusion: These aerosol particles are difficult to filter out of the air; because of their physical properties, new strategies must be developed to protect people from these virus aerosols.