The World Health Organisation (WHO) has confirmed that coronavirus is indeed spread through airborne droplets, as well as contact with surfaces.
The WHO’s technical leader for infection prevention and control, Benedetta Alleganzi, said that they had discussed and cooperated with the scientists who signed a letter urging them to reassess their advice about airborne droplets and viral transmission.
“We recognise that there is evidence in the field, such as on all surfaces exposed to the coronavirus, and we, therefore, believe that we must be open to these findings and understand their implications regarding the mode of transmission and also about precautions that need to be taken,” Alleganzi said.
The statement was issued after an open letter was signed by 239 scientists urging the WHO to be more open about the spread of the virus. Mounting evidence suggests that transmission might originate from liquid droplets floating in the air.
Communicable epidemiologist Maria Van Kerkove told the WHO Health Emergency Program that if some of the scientists who signed the journal’s publications were engineers rather than scientists. Kerkove also said it added to the growing knowledge about the importance of air ventilation to prevent the spread of the virus.
“We have talked about the possibility of airborne spread and aerosol transmission (solid particles in the air or liquid droplets) as one mode of spreading the virus,” she said. “We have seen the virus survive on surfaces. We have seen transmission through oral and fecal pathways, mother-to-child transmission, and transmission from animals to humans,” she added.
Kerkove also said that the WHO is working to put together a scientific article that summarises the latest information related to the transmission of the coronavirus which will be released in the next few weeks.
“This is a field of research that is really developing and there is some evidence emerging but it’s not definitive. Therefore, the possibility of airborne transmission in public spaces, especially in very specific conditions; in a dense, closed, and poorly ventilated place cannot be ruled out. However, the evidence still needs to be collected and needs further interpretation,” Alleganzi said.
Previously, the WHO said that the coronavirus transmission occurred through droplets; saliva that comes out of the mouth or nose when talking, coughing, sneezing, and even singing. The size of the droplets is quite large, so it was thought it would immediately fall to the ground or on to a surface when it is ejected from the mouth or nose. These droplets usually cannot be blown more than 1.5 metres.
The following are a number of consequences stated by WHO relating to the airborne transmission of the coronavirus:
The virus can float in the air for hours
Airborne transmission delivers aerosols or droplets that are very small. Aerosols are also known as micro droplets.
The size is less than five micrometres, while droplets are usually larger than five micrometres. Because it is small and lightweight, the aerosol carrying the SARS-CoV-2 coronavirus can survive floating in the air for several hours. In addition, this aerosol can also drift quite far.
Studies in the US claim that the SARS-CoV-2 coronavirus can live as a aerosol for up to four hours, while other studies, that are yet to be peer-reviewed, say it can last 16 hours.
Transmission doesn’t require direct contact
Airborne transmission is more dangerous because transmission can occur even if there is no contact at close range. This was revealed by an Epidemiologist from Australia’s La Trobe University, Hassan Vally.
If the transmission is via droplets, infection only occurs if healthy people inhale droplets from people infected with COVID-19. Aerosols can still survive in the air, even if the sick person has left the room.
With the recognition that transmission can occur by air, the application of social distancing becomes ineffective because the virus can drift far without close contact with those infected.
Open the window, clean the AC filter, use ultraviolet light
Another impact, according to Vally, is that the virus can be transmitted through airways and air conditioners. It’s recommended to open doors and windows, replace your air conditioner filter, and enhance outside air circulation.
Don Milton, an aerosol expert from the University of Maryland, USA, suggested public buildings and businesses consider using water purifiers and ultraviolet light (UV-C) devices to kill viruses.
Greater indoor risk
Vally also said the risk of transmission is higher in crowded and poorly ventilated rooms. Outdoor activities are noted as being safer than being in a crowded room. However, it is recommended to continue using a mask.
Tightening up on the use of masks
According to Vally, countries must tighten the requirements to use masks. Separately, Professor of Immunology, University of Pittsburg, Douglas Reed also agreed on the use of masks.
“You can reduce airborne transmission by using masks; wearing masks is a very effective and inexpensive way to slow down a pandemic,” Reed has been quoted as saying.
Air contagion is still debatable
Experts are actually still debating about airborne transmission. According to epidemiologist and infectious disease expert Paul Hunter, evidence of airborne transmission is still considered limited.
Hunter is also a professor from East Anglia University in England and a member of the WHO infection prevention committee. He believes airborne transmission only occurs in certain situations.
Epidemiologists say that in most COVID-19 cases, transmission occured through close contact. “Mostly due to droplet transmission,” explained Amesh Adalja, an infectious disease specialist at John Hopkins University.
Previously, the WHO noted that aerosol was only produced from a number of medical procedures and doesn’t occur due to talking, singing, sneezing, and coughing.
Source: CNN Indonesia