You're correct that the article doesn't mention antigen tests, ~~but the actual study[0] does~~: Edit: Apparantly the described test[1] is indeed for antibodie

You're correct that the article doesn't mention antigen tests, ~~but the actual study[0] does~~: Edit: Apparantly the described test[1] is indeed for antibodies. See child comment by projektfu. > Summary: > We studied SARS-CoV-2 seroprevalence among pregnant women in Norway by including all women who were first trimester pregnant (n=6520), each month from December 2019 through December 2020, in the catchment region of Norway’s second largest hospital. We used sera that had been frozen stored after compulsory testing for syphilis antibodies in antenatal care. The sera were analyzed with the Elecsys® Anti-SARS-CoV-2 immunoassay (Roche Diagnostics, Cobas e801). This immunoassay detects IgG/IgM against SARS-CoV-2 nucleocapsid antigen. [0] https://www.cambridge.org/core/journals/epidemiology-and-infection/article/prevalence-of-antibodies-against-sarscov2-among-pregnant-women-in-norway-during-the-period-december-2019-through-december-2020/0178544CC4F04FC0A55C7B0BD5F28AB8 https://www.cambridge.org/core/journals/epidemiology-and-inf... [1] https://diagnostics.roche.com/content/dam/diagnostics/Blueprint/en/pdf/cps/Elecsys-Anti-SARS-CoV-2-S-factsheet-SEPT-2020-2.pdf https://diagnostics.roche.com/content/dam/diagnostics/Bluepr...