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. 2024 Aug 30;58(15):32-38.
doi: 10.47895/amp.vi0.7618. eCollection 2024.

Method Validation Study for SARS-CoV-2 Viral RNA Detection in Cervical, Rectal, Amniotic Fluid, Placental, Umbilical Cord Blood, and Breastmilk Specimens in a Cohort of Unvaccinated Women in Manila, Philippines

Erlidia F Llamas-Clark 3rd  1   2 , Mayan U Lumandas  3 , Daniel C Villarico  3 , Amalea Dulcene D Nicolasora  3 , Maria Stephanie Fay S Cagayan  1   4 , Emmanuel S Baja  5   6 , Maria Esterlita T Villanueva-Uy  2   7 , Paulyn Jean B Rosell-Ubial  8 , Francisco M Heralde 3rd  9
Affiliations

Method Validation Study for SARS-CoV-2 Viral RNA Detection in Cervical, Rectal, Amniotic Fluid, Placental, Umbilical Cord Blood, and Breastmilk Specimens in a Cohort of Unvaccinated Women in Manila, Philippines

Erlidia F Llamas-Clark 3rd et al. Acta Med Philipp. .

Abstract

Objectives: To validate a method in detecting SARS-CoV-2 via RT-qPCR in pregnant and non-pregnant samples other than nasopharyngeal swabs and/or oropharyngeal swabs such as cervical, rectal, amniotic fluid, placental, umbilical cord blood, and breastmilk.

Methods: We performed a validation experiment using MGI easy extraction kits and BGI PCR kits on non-conventional specimens, including cervical, rectal, amniotic fluid, placental, umbilical cord blood, and breastmilk to detect and confirm the presence of SARS-CoV-2. In addition, we tested the validated method on 572 purposively sampled field-collected non-conventional specimens from a cohort of 109 unvaccinated pregnant and 47 unvaccinated non-pregnant women to assess which candidate non-conventional maternal- and fetal-associated specimens may contribute to maternal-fetal viral vertical transmission.

Results: Positive detection of SARS-CoV-2 viral RNA in non-conventional specimens was demonstrated and verified. Of the 572 non-conventional samples tested, 1.8% (10/572) were positively validated by RT-qPCR for SARS-CoV-2 in the maternal-associated specimens particularly the rectal (5), placental (1), and cervical (4) swabs among six pregnant and four non-pregnant individuals. In contrast, no SARS-CoV-2 viral RNA was detected in fetal-associated specimens.

Conclusion: The results of the validation study may serve as an additional diagnostic screening layer to support maternal-child care. Furthermore, viral detection in these non-conventional maternal specimens may also be utilized to provide guidance in the clinical management of neonates, and pregnant women during delivery.

Keywords: PCR; Philippines; SARS-CoV-2; amniotic fluid; breastmilk; placenta; pregnant women; umbilical cord.

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Conflict of interest statement

All authors declared no conflicts of interest.

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