Implemented indoor airborne transmission mitigation strategies during COVID-19: a systematic review

Seroprevalence study of the new coronavirus (SARS-CoV-2) in families and cohabitants of confirmed cases in Mashhad, Iran: a cross-sectional study

The seroepidemiological characteristics of the SARS-CoV-2 were investigated along with the secondary infection rate in the household of confirmed patients in a high-risk population in Mashhad, Iran. The current descriptive cross-sectional study includes a total of 154 confirmed cases of SARS-CoV-2 infection in Mashhad, Iran, from March 2021 to December 2021. The participants' families were screened for SARS-CoV-2 secondary infection rate, and a standard checklist containing the research parameters was completed by all participants. The participants' average age was 43.19 ± 9.86 years, of which 80 (51.9%) were female and the rest were male. Of the participants, 147 (95.5%) reported using face masks, and 83 (53.9%) were using masks all the time. IgG and IgM of COVID-19 were positive in 43 (27.9%) and 8 (5.2%) individuals, respectively. The average positive rate in the participants was 0.12 ± 0.24. Wearing masks when contracting with an infected patient (p < 0.001 and r = -0.370), using a separate room (p < 0.001 and r = -0.663), a separate toilet (p < 0.001 and r = -0.663) and the number of family members (p = 0.013 and r = 0.201) were significantly correlated to the positive rate of infection among the participants. Adherence to wearing masks and using separate rooms, and toilets by households in contact with a COVID-19-confirmed patient reduces the secondary transmission rate of the disease among healthy family members. In addition, the probability of COVID-19 transmission is higher in larger families.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13337-024-00903-9.

Monitoring the ventilation of living spaces to assess the risk of airborne transmission of infection using a novel Pocket CO2 Logger to track carbon dioxide concentrations in Tokyo

We employed carbon dioxide (CO2) concentration monitoring using mobile devices to identify location-specific risks for airborne infection transmission. We lent a newly developed, portable Pocket CO2 Logger to 10 participants, to be carried at all times, for an average of 8 days. The participants recorded their location at any given time as cinema, gym, hall, home, hospital, other indoors, other outgoings, pub, restaurant, university, store, transportation, or workplace. Generalized linear mixed model was used for statistical analysis, with the objective variable set to the logarithm of CO2 concentration. Analysis was performed by assigning participant identification as the random effect and location as the fixed effect. The data were collected per participant (seven males, four females), resulting in a total of 12,253 records. Statistical analysis identified three relatively poorly ventilated locations (median values > 1,000 ppm) that contributed significantly (p < 0.0001) to CO2 concentrations: homes (1,316 ppm), halls (1,173 ppm), and gyms (1005ppm). In contrast, two locations were identified to contribute significantly (p < 0.0001) to CO2 concentrations but had relatively low average values (<1,000 ppm): workplaces (705 ppm) and stores (620 ppm). The Pocket CO2 Logger can be used to visualize airborne infectious transmission risk by location to help guide recommendation regarding infectious disease policies, such as restrictions on human flow and ventilation measures and guidelines. In the future, large-scale surveys are expected to utilize the global positioning system, Wi-Fi, or Bluetooth of an individual's smartphone to improve ease and accuracy.

Investigating the effectiveness of a new indoor ventilation model in reducing the spread of disease: A case of sports centres amid the COVID-19 pandemic

The ventilation of buildings is crucial to ensure indoor health, especially when demanding physical activities are carried out indoors, and the pandemic has highlighted the need to develop new management methods to ensure adequate ventilation. In Spain, there are no specific ventilation regulations to prevent the spread of pathogens such as the coronavirus. Therefore, it is necessary to have a theoretical tool for calculating occupancy to maintain sports facilities in optimal safety conditions. The proposed theoretical method is based on the analysis of mathematical expressions from European standardisation documents and uses the concentration of CO2 as a bioeffluent. It is also based on the concept of background and critical concentration, which allows its application to be extrapolated to future crises caused by pathogens. This study presents a unique and novel dataset for sports centres. For this purpose, the calculation methods were applied to the data set provided by Mostoles City Council, Spain, during the pandemic years with the highest incidence of COVID-19, when the government introduced the assimilation of COVID-19 sick leave to occupational accidents. The data on this type of sick leave provided by the City Council correspond to the period between March 2020 and February 2022. Similarly, the data on the average use of sports facilities by activity, provided by the Sports Department, correspond to the years 2020 and 2021. In this way, it was possible to verify the effectiveness in preventing the spread of any type of coronavirus. In conclusion, the implementation of a theoretical occupancy calculation method based on the concentration of carbon dioxide as a bioeffluent can be an effective tool for the management of future crises caused by pathogens or hazardous chemicals in the air, and demonstrated its effectiveness in sports centres such as gyms, sports fields, and indoor swimming pools during the COVID-19 pandemic.