BTW talking about protective effect of the mask when donned by infected pax........
Don't bank on it unless if you are truly wearing 100% tested/confirmed masks and totally sealed.
You will never know even if the infected pax is wearing a mask and there is no Aircon, no 100% bao jiak one, unless if you are donning high filtration masks fully sealed which then reduces heckloads. It all depends in viral load, duration, distance, airflow etc.
Update : My kid and his classmates kena second round of CCT (close contact tracing) and confirmed HRW liao.
Coz the first round +ve pax did spread to 2 confirmed via PCR (from what we know via parents WA grp chat) coz the 1st round that time the kid was already symptomatic in class before he went to the general office sick bay near at the end of the day. So probably already 2-3 half-days worth of exposure liao. There was a 3rd kid actually who reported symptoms but parents said not positive so probably false alarm.
And so this second round also triggered their own HRWs. Coz the kids do take ART daily before going to school.
Shd have been more kiasee and dont go like the other half of the class is doing.....basket. Coz only Monday absent but the form teacher (that time taking report book) said to ask all the kids to come, no school......mini orientation for next year class and bring to new classroom + class cleanup etc. Wah lao, shd have known better.