SARS-CoV-2 seroprevalence among parturient women in Philadelphia

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Science Immunology  29 Jul 2020:
Vol. 5, Issue 49, eabd5709
DOI: 10.1126/sciimmunol.abd5709
  • Fig. 1 Geographical distribution of women tested for SARS-CoV-2 antibodies.

    Most serum specimens analyzed were from women living in areas within or immediately bordering the city of Philadelphia. Location of birth hospitals where serum samples were collected are shown as red crosses.

  • Fig. 2 Serum SARS-CoV-2 antibody levels in COVID-19 pandemic and pre-pandemic individuals.

    (A and B) Relative levels of SARS-CoV-2 IgG (A) and IgM (B) in serum collected before the COVID-19 pandemic (n = 834) and serum collected from COVID-19 recovered donors (n = 31). (C and D) Relative levels of SARS-CoV-2 IgG (C) and IgM (D) in serum collected from pregnant women from 2009 to 2012 (n = 140) and from 4 April to 3 June 2020 (n = 1293). Dashed lines indicate 0.48 arbitrary units, which was used to distinguish positive versus negative samples (see Materials and Methods). Serum samples that were below the cutoff for seropositivity were assigned an antibody level of 0.40 arbitrary units.

  • Table 1 Demographics and clinical characteristics of the study cohort.

    IQR, interquartile range; BMI, body mass index.

    CharacteristicsTotal (n = 1293)Seropositive* (n = 80)Seronegative (n = 1213)P value
    Age (in years), median (IQR)31 (27, 35)28 (24, 32)31 (27, 35)<0.001
    Race/ethnicity, n (%)
      Black/non-Hispanic53752 (9.7)485 (90.3)<0.001
      White/non-Hispanic4479 (2.0)438 (98.0)<0.001
      Hispanic/Latino12513 (10.4)112 (89.6)0.04
      Asian1061 (0.9)105 (99.1)0.01
      Other/unknown§785 (6.4)73 (93.6)0.93
    Pre-pregnancy BMI||, n (%)
      Overweight (25.0 to <30.0)34528 (8.1)317 (91.9)0.07
      Obese (≥30.0)33727 (8.0)310 (92.0)0.09
    Diabetes, n (%)11310 (8.9)103 (91.1)0.22
    Hypertension, n (%)40433 (8.2)371 (91.8)0.05
    Asthma, n (%)19413 (6.7)181 (93.3)0.75
    Cesarean delivery, n (%)40030 (7.5)370 (92.5)0.19
    Preterm delivery at
    gestational age <37 weeks,
    n (%)
    12811 (8.6)117 (91.4)0.23
    Live-born infant, n (%)128279 (6.2)1203 (93.8)0.51

    *Seropositivity was based on either IgG or IgM level of >0.48 arbitrary units.

    †Difference in maternal age was tested using Mann-Whitney U test, differences in proportion of all other characteristics were tested using χ2 tests or Fisher’s exact test as appropriate. For race/ethnicity and pre-pregnancy BMI, difference was tested at each level of the characteristic (e.g., proportion of Black women who were seropositive compared with proportion of non-Black women who were seropositive).

    ‡Row percentages are shown, which represent the percent of total in each characteristic (e.g., 9.7% of Black/Non-Hispanic women were seropositive).

    §Race/ethnicity was unknown for two seropositive and 26 seronegative women; race was abstracted from documentation at the time of admission and in clinical practice and is usually self-reported.

    ||Pre-pregnancy BMI was missing for 2 seropositive and 12 seronegative women; pre-pregnancy BMI was abstracted from documentation in the medical record or from patient’s self-reported entry in birth registration.

    ¶Diagnoses were based on delivery admission ICD-10 diagnosis codes for diabetes (O24, E08-E13, and Z79.4), hypertension (O10, O11, O13-O16, I10-I13, and I15), and asthma (J45).

    • Table 2 Timing of serology testing and seropositivity with respect to nasopharyngeal PCR testing.

      The table includes 1109 women tested for serology who were also tested by nasopharyngeal PCR anytime during pregnancy up to discharge from delivery admission. NP, nasopharyngeal.

      Serology timingNP-PCR positiveNP-PCR negative
      TestedSeropositive (%)TestedSeropositive (%)
      Before NP-PCR test1710 (58.8)3649 (2.5)
      0–6 days after NP-PCR test2615 (57.7)64716 (2.5)
      7–13 days after NP-PCR test55 (100.0)80
      14–20 days after NP-PCR test22 (100.0)70
      ≥21 days after NP-PCR test1414 (100.0)191 (5.3)
      Total6446 (71.9)104526 (2.5)

    Supplementary Materials

    • Supplementary Materials

      This PDF file includes:

      • Table S1. Relative levels of SARS-COV-2 IgG and IgM in serum collected from seropositive pregnant women (n = 80).

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