contagious...for even the currently vaccinated (w/o a Booster shot)...and certainly a threat to the unvaccinated.
Popular brands at a reasonable price (~$25) are "BinaxNOW" and "QuickVue"...available in most pharmacies.
Of course, get vaccinated with an mRNA vaccine...and this now means a 3rd shot ("Booster").
Link: https://fox8.com/news/coronavirus/at-home-covid-testing-kits-high-in-demand-across-northeast-ohio/