Only one confirmed case of Covid-19 in every thousand is traced to outdoor transmission, new figures reveal.
Of the 232,164 cases of Covid-19 recorded in the State up to March 24th this year, 262 were as a result of outdoor transmission, representing 0.1 per cent of the total.
There were 42 outbreaks associated with outdoor gatherings, with one community outbreak accounting for seven cases.
As The Irish Times reports, this involved an outdoor work activity which took place between two separate families, according to the Health Protection Surveillance Centre (HPSC) which monitors case numbers in the Republic.
There were 21 outbreaks on construction sites with 124 cases, and 20 outbreaks associated with sporting activities and fitness in which there were 131 cases.
The HPSC data was based on “locations which are primarily associated with outdoor activities, ie outdoor sports and construction sites, or outbreaks that specifically mention in comments that an outdoor location or activity was involved."
Community transmission
In addition, 20 per cent of all cases in the State result from community transmission where the source of the infection is not known.
The relatively low numbers of cases resulting from outdoor transmission in the Republic is mirrored in international studies.
A study of 1,245 cases in China found only three people were infected outdoors, and they were in conversation without masks. According to a review by the University of California of five global studies of transmission, the chances of getting Covid-19 in an indoor setting is 19 times greater than outdoors.
At the University of Canterbury, Prof Mike Weed studied 27,000 Covid-19 cases based on 6,000 different pieces of data.
One study was of 7,500 cases in China and Japan before lockdown in both of those countries. The number of cases associated with outdoor transmission was “so small to be insignificant”, he discovered.
Prof Weed said outdoor gatherings are safe if accompanied by proper risk management. For example, crowds could be allowed at sporting events if rules are observed around congregating in indoor venues beforehand.
“Our conclusion is that in many sectors, and for many sizes and formats, it should be possible to put appropriate evidence-based mitigations in place to deliver outdoor events and activities in a way that does not escalate the risk from sporadic transmission to cluster outbreak,” he said.
