There is an increased risk of severe coronavirus disease-2019 (COVID-19) during pregnancy, as well as an increased risk of adverse birth outcomes. Therefore, the aim of this study is to assess the safety, reactogenicity and immunogenicity of Ad26.COV2.S in adult participants in the second and/or third trimester of pregnancy.

Ad26.COV2.S (also known as Ad26COVS1) is a monovalent vaccine composed of a recombinant, replication incompetent adenovirus type 26 (Ad26) vector, constructed to encode the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) spike (S) protein.

For adult participants, the total study duration from screening until the last follow-up visit will be approximately 16 months (depending on the gestational age at enrollment and if the second dose of vaccine will need to be administered post-partum).

The study will consist of a screening phase (28 days), vaccination phase (3 months) and a follow up phase (up to 12 months post-partum [PP]). For neonates/infants (born to adult participants who received vaccination) the total study duration from birth until the last follow-up visit will be approximately 12 months.

Safety assessments will include immunogenicity assessments, physical examination, vital signs, clinical safety laboratory assessments, medical, obstetric and delivery history, neonate safety assessment, adverse events (AEs), serious adverse events (SAEs).