Ireland is seeing a “significant number” of Covid-19 transmissions outdoors when people “get too close,” a member of the National Public Health Emergency Team (Nphet) has warned.
Professor Philip Nolan, chair of Nphet’s modelling advisory group, said outdoor transmission was “most likely” through droplets, spray or soiled hands.
“A little more distance, not touching or shouting, or better hygiene might have prevented these infections,” he said in a series of posts on Twitter on the transmission of the disease.
Prior to the emergence of the more infectious Delta variant of the virus, just 0.1 per cent of the Republic’s cases were traced to outdoor transmission.
We are, for example, seeing a significant number of transmissions outdoors, when people get too close, most likely transmissions via droplets, spray or soiled hands; a little more distance, not touching or shouting, or better hygiene might have prevented these infections. 4/8
— Professor Philip Nolan (@President_MU) July 21, 2021
In a series of posts on Twitter, Prof Nolan argued that while ventilation was important in preventing the spread of Covid-19, the virus spreads by “droplets, fomites (contaminated objects or surfaces) and aerosols.”
“We do not know for certain the relative importance of each, so let’s be careful about all of them,” Prof Nolan said.
“The best available evidence, and the experience of public health doctors managing outbreaks, strongly suggest that the majority of transmissions occur with close contact, close enough for droplets, and aerosols in high concentration, to transmit the infection,” he continued.
“We think that transmission via contaminated surfaces is rare, but touching and soiled hands are likely to be important routes of transmission.
“We are, for example, seeing a significant number of transmissions outdoors, when people get too close, most likely transmissions via droplets, spray or soiled hands; a little more distance, not touching or shouting, or better hygiene might have prevented these infections.”
We need to pay attention to all, and avoid crowding and getting too close, indoors or outdoors
Prof Nolan said it was “bad and potentially dangerous advice to suggest that physical distance, minimising direct contact and hand hygiene are not effective infection prevention and control measures, and that ventilation is somehow more effective or more important.”
“I’m concerned that with the emphasis on ventilation, we forget the basics,” he added.
“Vaccination protects, staying home if symptomatic protects, distance protects, masks protect, good respiratory hygiene protects, hand-washing protects, ventilation protects.
“We need to pay attention to all, and avoid crowding and getting too close, indoors or outdoors.”
Across a room
The HSE has said that airborne transmission of the virus, where it spreads in very tiny water particles known as aerosols, can happen over a longer distance than droplets, such as across a room.
“Covid-19 can spread easily in crowded or poorly ventilated areas,” the HSE said.
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“To protect against airborne transmission, keep indoor spaces aired out (ventilated) by opening windows and doors when possible. This reduces the risk of infected air building up in a room, corridor or stairwell.
“It’s much safer to meet people outdoors than indoors, even if you keep more than two metres apart indoors.”
It comes as indoor dining is set to reopen from Monday for those with proof of immunity to Covid-19, along with accompanying children.