Cohort 1
Cohort 1 consists of 23 symptomatic women, ten of whom were confirmed to be SARS-CoV-2 infected via RT-PCR (Table S1). Antibody testing for IgG and IgM anti SARS-CoV-2 was conducted at various points during convalescence from day 0 to day 66 following a positive swab result. Anti-SARS-CoV-2 IgG antibodies were detected in 50% (5/10) of the RT-PCR positive SARS-CoV-2 women using the Roche and Abbot Architect platforms. Anti-SARS-CoV-2 IgM was detectable in seven women in the symptomatic cohort, one of whom was both RT-PCR negative on nasopharyngeal swab and IgG negative in serum (Supplementary table S3b). However, in view of this, it is possible that this may more likely reflect a false positive IgM. One woman did not mount an antibody response, when tested at day 10. She described very mild symptoms, presenting with an uncomplicated pyrexia and no respiratory symptoms.
The earliest evidence of a maternal IgG and IgM antibody response after a positive nasopharyngeal swab was at day 0. However, this patient reported first onset of symptoms 14 days prior to her nasal RT-PCR testing (patient c19-13, Figure 1). Therefore, we determined that the that the earliest response between swab positive (at symptom onset) and a demonstrably IgG antibody response was at day 4 (Patient c19-12, figure 1). Detectable antibody levels were not present in women tested at day 37 and 66 post a positive nasopharyngeal swab (Supplementary table S1).