Hi Maryellen,
There is an extensive document from Harvard about various COVID tests and a list of companies. This may provide a bit more information as you navigate the most cost effective way to do the testing.
https://csb.mgh.harvard.edu/covid
Does NH require PCR testing on fully vaccinated staff? CDC guidance is saying that testing fully vaccinated people isn’t necessary unless they are symptomatic. I know states don’t have to follow CDC guidance, but it’s interesting!