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Perspective from David A. Kaufman, MD
April 03, 2020
2 min read

Researchers report possible vertical transmission of SARS-CoV-2 in China

Perspective from David A. Kaufman, MD
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A neonate born to a mother infected with SARS-CoV-2 at a hospital in Wuhan, China, had elevated levels of immunoglobuin M, or IgM, and immunoglobulin G, or IgG, antibodies and abnormal cytokine test results 2 hours after birth, suggesting that the newborn was infected in utero, researchers reported in JAMA.

At 2 hours of age, the neonate’s SARS-CoV-2 IgG level was 140.32 AU/mL, and their IgM level was 45.83 AU/mL, the researchers wrote. Cytokines were elevated (interleukin-6, 28.26 pg/mL; interleukin-10, 153.60 pg/mL), and white blood cell count was 18.08 x 109/L. A chest CT was normal.

According to the paper, results from five real-time RT-PCR reaction tests on nasopharyngeal swabs taken between 2 hours and 16 days of age were all negative. At 16 days, the infant’s IgM and IgG levels were still elevated.

“Although infection at delivery cannot be ruled out, IgM antibodies usually do not appear until 3 to 7 days after infection and the elevated IgM in the neonate was evident in a blood sample drawn 2 hours after birth,” the researchers wrote.

IgG antibodies, unlike IgM antibodies, can be transmitted to the fetus through the placenta and appear later than IgM antibodies. The elevated IgG level may reflect maternal or infant infection.

The mother’s vaginal secretions tested negative for SARS-CoV-2, the researchers reported.

According to a second letter in JAMA, neonatal throat swabs and blood samples from newborns born from six pregnant women with confirmed COVID-19 at another hospital in Wuhan all tested negative via RT-PCR, but all six infants had antibodies against SARS-CoV-2 in neonatal blood sera samples.

According to the letter, all six mothers delivered via cesarean section in negative pressure isolation rooms while wearing protective masks. The infants were isolated from their mothers immediately after delivery. As of March 8, none of the infants were presenting symptoms.

Both studies were limited by small sample sizes. A previous report showed no vertical transmission among nine infants in China born to mothers with COVID-19. by Ken Downey Jr.


Dong L, et al. JAMA. 2020; doi:10.1001/jama.2020.4621.

Zeng H, et al. JAMA. 2020; doi:10.1001/jama.2020.4861.

Disclosures: The authors report no relevant financial disclosures.