Despite the increased risk of adverse health outcomes for pregnant women with COVID-19, phase three vaccine trials did not include pregnant or lactating women. Collier et al conducted an exploratory, prospective cohort study using a convenience sample to evaluate the immunogenicity of COVID-19 vaccines in this population. The study recruited 131 women pregnant, lactating, or nonpregnant women of whom 103 have received the Moderna or Pfizer-BioNTech vaccine and 28 have been previously infected with SARS-CoV-2. In pregnant, lactating, and non-pregnant women, humoral and cellular immune responses were clearly shown. Median RBD-IgG binding antibody titers were higher among those vaccinated than among those who had been previously infected. Binding and neutralizing antibodies were detected in infant cord blood and maternal breast milk, suggesting a transferal of protection from vaccinated mothers to newborns. Pregnant, lactating, and nonpregnant women who had been vaccinated exhibited both humoral and cellular immune responses to both B.1.1.7 and B.1.351 variants of concern, though the humoral response was markedly lower for the variants compared to the original virus. Overall, these results suggest that COVID-19 vaccine was immunogenic among pregnant and lactating women.