and possessions of the United States. (e) Regulations The Secretary shall issue such regulations or other guidance as may be necessary or appropriate to carry out the purposes of this section, including— (1) not later than 30 days after the date of the enactment of this section, a list of the population census tracts described in subsection (a)(1), and (2) not later than 60 days after the date of the enactment of this section, regulations or other guidance regarding the designation of population census tracts described in subsection (a)(2). . (b) Effective date The amendments made by this section shall apply to taxable years beginning after December 31, 2019. 3. Authority to support development of population health products (a) Definitions (1) Qualified countermeasure Subparagraph (A) of section 319F–1(a)(2) of the Public Health Service Act (42 U.S.C. 247d–6a(a)(2)) is amended to read as follows: (A) Qualified countermeasure The term qualified countermeasure means a drug (as that term is defined by section 201(g)(1) of the Federal Food, Drug, and Cosmetic Act ( 21 U.S.C. 321(g)(1) )), biological product (as that term is defined by section 351(i) of this Act ( 42 U.S.C. 262(i) )), or device (as that term is defined by section 201(h) of the Federal Food, Drug, and Cosmetic Act ( 21 U.S.C. 321(h) )), that the Secretary determines to be a priority consistent with sections 302(2) and 304(a) of the Homeland Security Act of 2002— (i) to diagnose, mitigate, prevent, or treat harm from any biological agent (including organisms that cause an infectious disease), toxin, chemical, radiological, or nuclear agent that may cause a public health emergency affecting national security