Directing traffic on a cold and gray day during a recent vaccination clinic in Orleans, retired physical therapist Robin McIntyre, of Bourne, said she felt an obligation to volunteer to help during the pandemic. “This is bigger than just little Cape Cod, for sure," said McIntyre, whose neon vest with the initials MRC identified her as a volunteer for the Cape Cod Medical Reserve Corps. "This is a huge thing for our world. It’s important to be doing this.” McIntyre is one of a small army of volunteers, mostly retirees, standing between Cape Codders and COVID-19. Local officials hope to expand their already growing ranks as vaccination efforts ramp up on Cape Cod.