- First, the over-threading events explain a significant transmission of SARS-CoV-2; indeed, such events may be the main drivers of the pandemic.6 Detailed analyzes of human behaviors and interactions, room sizes, ventilation and other variables in choral concerts, cruise ships , slaughterhouses, nursing homes, and correctional facilities, among others, have shown patterns, for example, long-range transmission and overdispersion of the basic reproduction number (R0), discussed below, consistent with the airborne spread of SARS-CoV-2 which cannot be adequately explained by droplets or fomites.6 The high incidence of such events strongly suggests the dominance of aerosol transmission.
- Second, long-range transmission of SARS-CoV-2 between people living in adjacent rooms, but never in the presence of each other has been documented in quarantine hotels.7 Historically, it was not possible to prove long-range transmission than in the total absence of community transmission.4
- Third, asymptomatic or presymptomatic transmission of SARS-CoV-2 by people who do not cough or sneeze is likely to account for at least one-third, and possibly up to 59%, of all transmission to the virus. global scale and is a key means of spread of SARS-CoV-2 worldwide, 8 from a predominantly airborne mode of transmission. Direct measurements show that talking produces thousands of aerosol particles and few large droplets, 9 which takes over the air route.
- Fourth, the transmission of SARS-CoV-2 is higher indoors than outdoors10 and is considerably reduced by indoor ventilation.5 Both observations support a predominantly airborne route of transmission.
- Fifth, nosocomial infections have been documented in healthcare organizations, where there have been strict contact and droplet precautions and the use of personal protective equipment (PPE) designed to protect against exposure to droplets, but not aerosols.11
- Sixth, viable SARS-CoV-2 has been detected in the air. In laboratory experiments, SARS-CoV-2 remained infectious in air for up to 3 h with a half-life of 1 h. 1 Viable SARS-CoV-12 has been identified in air samples from rooms occupied by covid-2 patients in the absence of aerosol-generating healthcare procedures19 and from air samples from the car of an infected person.13 Although others Studies have failed to capture viable SARS-CoV-14 in air samples, as is to be expected. Sampling for airborne virus is technically difficult for several reasons, including the limited effectiveness of some sampling methods for the collection of fine particles, viral dehydration during collection, viral damage due to forces. impact (resulting in loss of viability), the re-aerosolization of the virus during viral collection and retention in the sampling equipment.2 Measles and tuberculosis, two predominantly airborne diseases, have never been cultivated in the air of the room.3
- Seventh, SARS-CoV-2 has been identified in air filters and construction ducts in hospitals with patients with COVID-19; these locations could only be reached by aerosols.16
- Eighth, studies of infected caged animals that were linked to uninfected caged animals through an air duct have shown the transmission of SARS-CoV-2 which cannot be adequately explained. than by aerosols. 17
- Ninth, no study to our knowledge has provided strong or consistent evidence to refute the hypothesis of airborne transmission of SARS-CoV-2. Some people have avoided infection with SARS-CoV-2 when sharing air with infected people, but this could be due to a combination of factors, including variation in the amount of viral shedding between infectious people by orders of magnitude and different environmental conditions (particularly ventilation) .18 Individual and environmental variations mean that a minority of primary cases (especially individuals who exert high levels of the virus to the indoor, overcrowded environments with poor ventilation) account for the majority of secondary infections, which is supported by high-quality contact tracing data from several countries.19, 20 Large variation in respiratory viral load of SARS- CoV-2 countered arguments that SARS-CoV-2 cannot be airborne because the virus has a lower R0 ( estimated at around 2 · 5) 21 measles (estimated at around 15), 22 especially since R0, which is an average, does not take into account the fact that only a minority of infectious individuals lose large amounts of the virus. Overdispersion of R0 is well documented in COVID-19.23
- Tenth, there is little evidence to support other dominant routes of transmission, i.e., respiratory droplet or fomitis.9, 24 Ease of infection between people in close proximity to each other. others has been cited as evidence of respiratory transmission of SARS-CoV-2 droplets. However, near transmission in most cases as well as distant infection for a few when sharing air is more likely to be explained by the dilution of exhaled aerosols with distance from an infected person. 9 The mistaken assumption that proximity transmission involves large respiratory droplets or fomites has always been used for decades to deny airborne transmission of tuberculosis and measles.15, 25 This has become medical dogma, ignoring the direct measurements of aerosols and droplets that reveal defects such as the overwhelming number of aerosols produced in respiratory activities and the arbitrary particle size limit of 5 μm between aerosols and droplets, instead of the correct limit of 100 μm. 15, 25 It is sometimes argued that since respiratory droplets are larger than aerosols, they must contain more virus. However, in diseases where pathogen concentrations were quantified by particle size, smaller aerosols had higher pathogen concentrations than droplets when both were measured.15
In conclusion, we propose that it is a scientific error to use the absence of direct evidence of SARS-CoV-2 in some air samples to cast doubt on airborne transmission while neglecting the quality. and the strength of the overall evidence base.
There is strong and consistent evidence that SARS-CoV-2 is spread by air transmission. While other routes can help, we believe the air route is likely to be dominant. The public health community should act accordingly and without further delay. the study