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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-B) Relative levels of SARS-CoV-2 IgG (A) and IgM (A) in serum collected before the COVID-19 pandemic (n = 834) and serum collected from COVID-19 recovered donors (n = 31). (C-D) Relative levels of SARS-CoV-2 IgG (C) and IgM (D) in serum collected from pregnant women from 2009-2012 (n = 140) and from April 4-June 3, 2020 (n = 1,293). Dashed lines indicate 0.48 arbitrary units, which was used to distinguish positive versus negative samples (see 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.

    CharacteristicsTotal
    (n = 1,293)
    Seropositive1
    (n = 80)
    Seronegative
    (n = 1,213)
    p-value2
    Age (in years), median (IQR)31 (27, 35)28 (24, 32)31 (27, 35)<0.001
    Race/ethnicity, n (%)3
    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/Unknown4785 (6.4)73 (93.6)0.93
    Pre-pregnancy BMI5, n (%)3
    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
    Diabetes6, n (%)311310 (8.9)103 (91.1)0.22
    Hypertension6, n (%)340433 (8.2)371 (91.8)0.05
    Asthma6, n (%)319413 (6.7)181 (93.3)0.75
    Cesarean delivery, n (%)340030 (7.5)370 (92.5)0.19
    Preterm delivery at gestational age <37 weeks, n (%)312811 (8.6)117 (91.4)0.23
    Live-born infant, n (%)31,28279 (6.2)1,203 (93.8)0.51

    1Seropositivity was based on either IgG or IgM level >0.48 arbitrary units. 2Difference 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 to proportion of non-Black women who were seropositive). 3Row percentages are shown which represent the percent of total in each characteristic (e.g., 9.7% of Black/Non-Hispanic women were seropositive). 4Race/ethnicity was unknown for 2 seropositive and 26 seronegative women; race was abstracted from documentation at time of admission and in clinical practice, is usually self-reported. 5Pre-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. 6Diagnoses were based on delivery admission International Classification of Diseases, 10th revision diagnosis codes for diabetes (O24, E08-E13, Z79.4), hypertension (O10, O11, O13-O16, I10-I13, I15), and asthma (J45). BMI, body mass index; IQR, interquartile range.

    • Table 2 Timing of serology testing and seropositivity with respect to nasopharyngeal PCR testing1.

      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)1,04526 (2.5)

      1The table includes 1,109 women tested for serology who were also tested by nasopharyngeal PCR anytime during pregnancy up to discharge from delivery admission. NP, nasopharyngeal; PCR, polymerase chain reaction.

      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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