New Alarming Case Shows Omicron and Newer SARS-CoV-2 Strains Can Still Damage Placenta in Pregnant Women!
Nikhil Prasad Fact checked by:Thailand Medical News Team Mar 26, 2025 3 days, 20 minutes ago
Medical News: A team of French medical researchers has reignited concern over the lingering dangers of SARS-CoV-2 variants in pregnant women, even in the Omicron era, that has been mistakenly regarded as milder by many. A recent case study highlights the reappearance of previously known deadly placental lesions caused by the SARS-CoV-2 - this time in a woman infected with an Omicron subvariant and undergoing immunosuppressive therapy with anti-CD20 monoclonal antibodies.
New Alarming Case Shows Omicron and Newer SARS-CoV-2 Strains Can Still Damage Placenta in Pregnant Women!
The groundbreaking findings stem from a collaboration between scientists and physicians from IUCT Oncopole France, Paule de Viguier Maternity Hospital France, CHU Toulouse France, and the Federal Institute of Biology at CHU de Toulouse. This
Medical News report revisits a concerning triad of placental damage - trophoblastic necrosis, chronic histiocytic intervillitis, and massive perivillous fibrin deposits - that has been well-documented in earlier COVID-19 waves but had largely vanished in the Omicron period.
A Dangerous Resurgence After Years of Absence
Since early 2020, medical professionals had identified this specific set of placental lesions as a hallmark of SARS-CoV-2 complications in pregnancy. These lesions, found in infected expectant mothers, could rapidly lead to fetal death within weeks of viral exposure - especially during infections with the original, Alpha, and Delta variants. But after the Omicron variant emerged in late 2021 and quickly became the dominant global strain, the prevalence of such severe placental damage dropped drastically. Hospitals, including the high-volume maternity wing at CHU Toulouse (which handles nearly 5,000 births per year), reported no similar cases in almost three years.
That changed in September 2024, when a pregnant woman with a compromised immune system - due to treatment with anti-CD20 drugs used for certain autoimmune diseases and lymphomas - was admitted to the emergency room with symptoms of infectious pneumonia. Her case, however, would soon unveil more alarming insights.
Strong Virus Presence Found in Damaged Placental Tissue
Upon delivery, the placenta was sent for pathological analysis. Doctors were stunned to observe the re-emergence of the previously noted lesion triad, typically associated with pre-Omicron variants. Further investigation using immunohistochemistry techniques showed strong SARS-CoV-2 nucleocapsid protein positivity in necrotic trophoblasts - the same kind of positive markers seen in the most aggressive COVID variants in 2020 and 2021.
Additionally, an RNA test conducted on formalin-fixed, paraffin-embedded (FFPE) placental tissue yielded highly positive results via RT-PCR, with a very low cycle threshold (Ct = 18), indicating a high viral load in the placenta. Although complete viral genome sequencing was not feasible, epidemiological data confirmed that the only SARS-CoV-2 variant circulating in Toulouse during this period was the JN.1* (24A) lineage, predominantly represen
ted by its KP.3.1.1 (24C) subvariant.
Omicron’s Supposed Mildness May Not Apply to Immunocompromised Pregnancies
This case reaffirms that despite the popular belief that Omicron and its descendants are less dangerous, the virus still retains its capacity to severely affect maternal and fetal health - especially among patients with weakened immune defenses. The researchers caution that placental “tropism,” or the virus’s ability to infect and damage placental tissue, persists in newer strains, albeit at lower levels, and can be reactivated under specific conditions like immunosuppression.
The findings challenge the complacency that has crept into public and medical perception regarding Omicron's relative harmlessness. In fact, for vulnerable groups - including pregnant women on immunosuppressants - the risks remain serious and underrecognized.
Conclusions and Implications
This new case study brings a timely reminder that SARS-CoV-2 continues to evolve in unpredictable ways and can still wreak havoc in the human body, particularly in individuals with impaired immune systems. The reappearance of this dangerous placental lesion triad after three years of absence shows that the virus's destructive capabilities are not a thing of the past. It also raises urgent questions about how many similar cases may have gone undetected or misdiagnosed, especially in settings without advanced pathological surveillance.
More importantly, this study underscores the need for continuous vigilance and monitoring of pregnant women infected with COVID-19, especially those with pre-existing conditions or undergoing therapies like anti-CD20 treatment. While Omicron may be milder for the general population, its potential for causing life-threatening complications in certain subgroups should not be underestimated. Clinicians should consider enhanced monitoring and possibly adjusted care protocols for these high-risk patients to prevent fetal loss or maternal harm.
The study findings were published in the peer reviewed journal: Placenta.
https://www.sciencedirect.com/science/article/abs/pii/S0143400425000864
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