Logistic regression analyses were used to calculate adjusted odds ratios (AOR) controlling for demographic factors and vaccination. Adjusted Population attributable fractions (APAF) were calculated for different classes of activity based on the following formula APAF = p * (1-1/Relative Risk) where p=proportion of those with COVID-19 who had the exposure of interest and AOR was taken as a proxy for relative risk.
In the second wave of the pandemic when there were intense restrictions:
Leaving home for work - AOR 1.20 (95% CI 1.02 – 1.42), APAF 7%;
Public transport - AOR > once per week 1.82 (1.49 – 2.23), APAF 12%;
Shopping (AOR for shopping > once per week 1.69 (1.29 – 2.21), APAF 35%
Other non-household activities such as use of hospitality and leisure venues were rare due to restrictions and there were no significant associations with infection risk.
In September-November 2021 when there were no restrictions
Leaving home for work AOR 1.20 (1.03-1.98) APAF = 9%,
Public transport more than once per week (AOR 1.28 (1.05-2.02) APAF 14%,
Shopping AOR for weekly shopping 2.18 (1.41-3.47) APAF 36%
Other activities (AOR for > weekly 1.20 (0.97-1.49) APAF 11%
In September-November 2021 for public transport activities there was good evidence of increased risk of transmission for using a bus AOR 1.31 (95% CI 1.07-1.61),
some evidence of increased transmission for using a taxi (1.19 (0.95-1.48),
using an overground train or tram (1.18 (0.95-1.46)
but no evidence for using an underground train (1.02 (0.76-1.36).
In September-November 2021 for other indoor non--household activities other than work, public transport or shopping there was good evidence of increased risk of transmission for those eating at a restaurant, café (AOR 1.29 (95% CI 1.05-1.61),
there was some evidence of increased transmission for going to a pub, bar or club (AOR for attending more than once per week 1.28 (0.99-1.66),
going to a party (1.27 (0.99-1.62), going to the gym or indoor sports (1.27 (0.98-1.63).
There was no good evidence of increased risk of transmission for attending theatres, cinema, concert or sports event (AOR 1.09 (0.89-1.34),
going to a hairdresser, barber, nail salon or beauty parlor (AOR 0.81 (95% CI 0.66-0.99).
In September-November 2021 for outdoor activities there was
Good evidence of increased risk of transmission in those Playing a sport outdoors (1.36 (1.03-1.79)
No good evidence of increased risk from other outdoor activities including being outside at a pub, bar or club, eating outside at a restaurant or café and going to a party outside