Study Finds COVID-19 Not Present in Placental Tissue After Maternal Recovery

Concerns about SARS-CoV-2's effects on placental health have persisted since early in the COVID-19 pandemic. Infection during pregnancy has been linked to serious complications, including increased rates of stillbirth, preterm birth, and placental insufficiency. A condition known as COVID-19 placentitis—characterized by a triad of trophoblastic necrosis, chronic histiocytic intervillositis, and excessive perivillous fibrin deposition—has been identified as a key mechanism driving these adverse outcomes. In severe cases, this pathological pattern has been shown to destroy more than 75% of placental tissue, effectively preventing adequate fetal oxygenation and leading to fetal demise.^1-5

Prior research demonstrated that SARS-CoV-2 actively replicates within placental tissue during acute maternal infection, with more severe maternal illness correlating with greater placental viral burden and the highest rates of replication observed in cases of stillbirth. Clinicians and patients have been left questioning whether the virus lingers in the placenta after the mother recovers from infection.⁶

About the Study

A new study published in JAMA Network Open by researchers at Yale School of Medicine sought to answer that question directly. Led by Shelli F. Farhadian, MD, PhD, associate professor of medicine; and Harvey J. Kliman, MD, PhD, director of the Reproductive and Placental Research Unit, the team analyzed placental samples collected at delivery from pregnant women who had recovered from COVID-19 between 40 and 212 days prior to delivery. The study cohort included pregnancies ending in both healthy births and stillbirths.¹

Using sensitive laboratory techniques, including viral protein detection and RNA in situ hybridization, investigators examined placental tissue for any evidence of residual SARS-CoV-2. These methods are specifically designed to detect intact viral protein and genetic material, making them well suited for identifying persistent or latent infection.¹

Key Findings

Across all tested samples, researchers found no evidence of SARS-CoV-2 RNA or protein in the placenta, regardless of whether the delivery resulted in a healthy birth or a stillbirth. These results held even in samples collected more than 6 months after the mother's initial infection, suggesting the placenta does not serve as a long-term viral reservoir after recovery.¹

However, the study also found that some placentas displayed structural and inflammatory changes resembling those observed during acute COVID-19 placentitis, even in the absence of a detectable virus. This finding suggests that immune-mediated damage incurred during active infection can persist well beyond viral clearance, potentially contributing to placental dysfunction and adverse pregnancy outcomes.¹

"These results indicate that the placenta is effective at clearing the virus after maternal recovery," Kliman said in a news release. "But the structural changes we observed suggest that the damage incurred during infection may persist."¹

Clinical Implications

The findings carry meaningful implications for obstetric and pharmacist-guided care of pregnant patients with a history of COVID-19. The absence of persistent viral infection rules out ongoing placental viral activity as a source of continued fetal risk in recovered patients—an important reassurance for clinicians and patients navigating pregnancy after COVID-19 illness.

Nevertheless, the structural residue left by acute placentitis underscores the importance of vaccination prior to or during pregnancy. Evidence has shown that maternal COVID-19 vaccination significantly reduces the risk of developing SARS-CoV-2 placentitis and associated stillbirth in women who contract the virus during pregnancy. The CDC continues to recommend COVID-19 vaccination for pregnant individuals, noting that vaccination has not been associated with increased health risks for them or their babies and may help protect against the most severe placental complications.^7,8

From a pharmacist's perspective, counseling pregnant patients on the benefits and safety of COVID-19 vaccination remains an essential component of prenatal care. Vaccine hesitancy among pregnant patients persists, with fears about fetal effects continuing to be cited as a primary barrier to uptake. Pharmacists are well positioned to address these concerns using current evidence, emphasizing that vaccination protects against the very placental damage that may linger even after viral clearance.⁹

Study Limitations and Future Directions

The authors acknowledged that the study is limited by its small sample size and retrospective design. Additional prospective research is needed to determine how frequently placental structural injury occurs following SARS-CoV-2 infection across a broader population, as well as the long-term clinical consequences of those changes for fetal and neonatal outcomes.¹

REFERENCES

1. Farhadian SF, Orlinick B, Milano KM, Mekael D, Kliman HJ. Absence of SARS-CoV-2 in placental tissue after maternal COVID-19. JAMA Netw Open. 2026;9(4):e268567. doi:10.1001/jamanetworkopen.2026.8567

2. Li A, Schwartz DA, Vo A, et al. Impact of SARS-CoV-2 infection during pregnancy on the placenta and fetus. Semin Perinatol. 2024;48(4):151919. doi:10.1016/j.semperi.2024.151919

3. Merriel A, Fitzgerald B, O'Donoghue K. SARS-CoV-2—placental effects and association with stillbirth. BJOG. 2024;131(4):385-400. doi:10.1111/1471-0528.17698

4. Stenton S, McPartland J, Shukla R, et al. SARS-COV2 placentitis and pregnancy outcome: a multicentre experience during the alpha and early delta waves of coronavirus pandemic in England. EClinicalMedicine. 2022;47:101389. doi:10.1016/j.eclinm.2022.101389

5. Schwartz DA, Mulkey SB, Roberts DJ. SARS-CoV-2 placentitis, stillbirth, and maternal COVID-19 vaccination: clinical-pathologic correlations. Am J Obstet Gynecol. 2023;228(3):261-269. doi:10.1016/j.ajog.2022.10.001

6. Radan AP, Renz P, Raio L, et al. SARS-CoV-2 replicates in the placenta after maternal infection during pregnancy. Front Med (Lausanne). 2024;11:1439181. doi:10.3389/fmed.2024.1439181

7. Zels G, Colpaert C, Leenaerts D, et al. COVID-19 vaccination protects infected pregnant women from developing SARS-CoV-2 placentitis and decreases the risk for stillbirth. Placenta. 2024;148:38-43. doi:10.1016/j.placenta.2024.01.015

8. CDC. COVID-19 vaccination for women who are pregnant or breastfeeding. Updated February 10, 2026. Accessed April 23, 2026. https://www.cdc.gov/covid/vaccines/pregnant-or-breastfeeding.html

9. Nourian T, Sarandili S, Mousavi S, Mirmohammadkhani M, Rahmanian M. Maternal and neonatal outcomes in pregnant women vaccinated against COVID-19 compared to an unvaccinated group. Int J Womens Health. 2025;17:4131-4142. doi:10.2147/IJWH.S548444