In ovariectomized mice and in vitro there is increased vaginal HSV-2 transmission following treatment with progesterone (53, 54) while in other studies using ovariectomized mice treated with IFNλ1, vaginal, cervical, and uterine ZIKV infection was greater in mice treated with P alone, compared to mice treated with both E2 and P (55). Here, IFNL1 is linked to Zika virus infectious disease.