Findings from nine late-stage pregnancies in which the mother was infected with the novel coronavirus suggest "vertical transmission" -- passing infection from mother to infant in utero -- does not occur.

In nine pregnant women with laboratory-confirmed COVID-19 pneumonia (the new name for the novel coronavirus infection sweeping China), samples from their infants, including amniotic fluid, cord blood, and a neonatal throat swab, tested negative for the virus, reported Yuanzhen Zhang, PhD, of Wuhan University in China, and colleagues, writing in The Lancet.

Researchers performed a retrospective review of pregnant women admitted to an academic medical center in Wuhan from Jan. 20 to Jan. 31, 2020. In addition to amniotic fluid, cord blood, and a neonatal throat swab, researchers also collected breast milk samples.

All patients were in their third trimester, delivered via cesarean section, and were ages 26 to 40. No women had any chronic medical conditions, such as diabetes, chronic hypertension, or cardiovascular disease. Seven women presented with a fever, four had a cough, and three had myalgia or muscle pain.

None developed severe COVID-19 pneumonia or died, and all nine had liveborn infants, whose samples all tested negative for the virus, including the mother's breast milk.

"Findings from these cases suggest that there is currently no evidence for intrauterine infection caused by vertical transmission in women who develop COVID-19 pneumonia late in pregnancy," they wrote.

In an accompanying comment, Jie Qiao, MD, of Peking University Third Hospital in Beijing, noted that while previous studies found SARS during pregnancy was associated with a high incidence of complications, such as spontaneous miscarriage, preterm delivery, and intrauterine growth restriction, the same does not seem to be the case, so far, among women with COVID-19 infection.

However, Qiao noted the small number of cases and the short duration of the study, suggesting that more research into this population is needed.

"Pregnant women are susceptible to respiratory pathogens and to development of severe pneumonia, which possibly makes them more susceptible to COVID-19 infection than the general population, especially if they have chronic diseases or maternal complications," Qiao wrote. "Therefore, pregnant women and newborn babies should be considered key at-risk populations in strategies focusing on prevention and management of COVID-19 infection."

Isolated reports from China of a neonate testing positive after being born to an infected mother first raised the possibility of vertical transmission.

"Figuring out how baby got the disease and figuring out when baby got sick can be fairly challenging," Loralei Thornburg, MD, of the University of Rochester Medical Center in Rochester, New York, told MedPage Today when asked about the early reports. Infections can develop in newborns simply through postnatal contact with an infected mother, she noted.

CDC Reports Testing Development, Snafus

"We have the beginnings of a serologic test [for this novel coronavirus]," Nancy Messonnier, MD, director, CDC's National Center for Immunization and Respiratory Diseases, said in a press briefing on Wednesday.

But it takes time to develop, she added, saying that the agency is continuing to collect specimens over time to understand what the immune response to the disease looks like. Within 3-4 weeks, the agency hopes to have a test available, she said.

Messonnier also commented about how the diagnostic test kits shipped to state public health labs hit a bit of an unexpected snag. Apparently, when state labs tried to verify that the test worked, the test came back as "inconclusive." She emphasized the test was not used on patient samples, nor was it something the labs were doing incorrectly, but a "collective problem."

"We think it might be an issue with one of the three assays, one of the reagents wasn't performing consistently," Messonnier said, adding that they are manufacturing the reagent.

She also added that the CDC was in talks with healthcare industry partners to assess the availability of personal protective equipment.

"At this time, some partners are reporting higher than usual demand for N95 respirators and facemasks," Messonnier noted.

She reiterated that CDC does not recommend the public wear facemasks, as they are meant for patients or for household contacts/caregivers of infected people when patients are not wearing a mask themselves.

WHO Sets COVID-19 Research Agenda, Priorities

Easy to apply diagnostics, best approaches for infection prevention, and potential therapies, including vaccines, for patients with COVID-19 disease were all discussed at the research and innovation forum on Tuesday and Wednesday. Hosted by the World Health Organization (WHO) in collaboration with the Global Coalition for Infectious Diseases Preparedness, it included major research funders and more than 300 scientists.

In a statement released Wednesday, WHO officials noted that in addition to developing a "master plan" to ensure clinical trials are done "coherently and consistently," the agency continues to ship diagnostic kits to laboratories around the world.

Currently, they noted a number of drugs put forward for testing, including the HIV therapy, ritonavir/lopinavir (Kaletra) and remdesivir, an investigational drug that was developed to treat Ebola, but added they will have to wait "a few weeks to see if anything has a positive signal." There are also four vaccine candidates in development, they noted.

Officials added they are sending masks, gloves, gowns, and other personal protective equipment to protect frontline health workers in 18 countries.

Interestingly, they noted that looking at current transmission chains, only eight cases worldwide had "no plausible explanation for exposure," indicating they have a "good view" of the virus at a global level.