The decades-long effort to produce a workable HIV vaccine has hardly been a waste of public and private resources. To the contrary, the scientific know-how acquired along the way has served as the critical foundation for the development of vaccines against the novel, pandemic SARS-CoV-2 virus....

"We employ a latent class model to assess the impact of Mexico's Seguro Popular ("SP") program on the number of prenatal visits in a cross-sectional sample of 4,381 women who gave birth during 2002-2005. We specify an ordered probit model to permit a pregnant woman's probability of membership in...