Rapid antigen tests Tracy, what do you mean by a monthly health monitoring program?
Rapid antigen testing kits only tell you if you have an active infection today that is producing the covid spike protein.
Rapid antigen testing kits can not tell you if you are likely to have an active infection tomorrow or next month.
If you have a covid infection that is not at a high viral load, the rapid antigen testing is less likely to pick it up. The high sensitivity % quoted is usually measuring people at a high viral load and therefore people who are most infectious (and the people you are least likely to want to come in the building).
From my research, from a workplace point of view, it seems the rapid antigen testing is most useful when someone is symptomatic in the workplace, and it could be asthma, allergies, a cold, etc or covid. The test will help to rule out covid and provide reassurance. (acknowledging that sick people need to stay home of course). Or as MattD2 says, you are working with a close contact, household contact or workplace contact situation and people on the periphery of the public health advice want/need extra testing,
My thinking is that if you are doing surveillance testing then every 3-4 days is most likely to pick up an infection, providing the person has a high enough viral load (with or without symptoms) and depending on all the other covid mitigation controls you have in place and the risks of transmission in your workplace. Once you start this system it is for the long haul, and the costs add up.
A pos rapid antigen test then needs PCR testing through the public health system.
I am guessing more guidance will follow from WorkSafe/MBIE/MoH etc. The info is being updated daily at the moment.
https://www.mbie.govt.nz/about/news/lessons-learnt-from-rapid-antigen-testing-trial/
https://www.health.govt.nz/our-work/diseases-and-conditions/covid-19-novel-coronavirus/covid-19-health-advice-public/assessment-and-testing-covid-19/rapid-antigen-testing
https://www.nature.com/articles/s41598-021-88498-9