The daughter of a pregnant woman who was cured of Ebola has survived and tested negative for the virus, in a case that has been described as a medical miracle.

Sylvana, born on 6 January and weighing 3.7kg, is the second baby in the world known to have survived after being born to a woman who had Ebola. It is the first case in which both mother and baby have survived.

In December, Sylvana’s mother was admitted to the Ebola treatment centre in Beni, in the north-east of the Democratic Republic of the Congo (DRC), where the response to the Ebola outbreak has been hampered by violence. The mother was cured and discharged, and her baby’s development was monitored before she returned to the centre to give birth.

Sylvana’s mother with her newborn child, one of only two known to have survived after being born to an Ebola victim. Photograph: Courtesy of Ministère de la Santé RDC

Across the country, there have been 577 confirmed cases of Ebola and 377 deaths since an outbreak was declared in August last year, according to the World Health Organization (WHO).

Dr Séverine Caluwaerts, a referent gynaecologist with Médecins Sans Frontières (MSF), said Sylvana’s birth offered a message of hope to other women.

“Before, the message was that your baby will always get Ebola. Now we can say we have had cases where the baby has survived, is healthy and without problems,” she said.

Caluwaerts was part of the team who treated Nubia, the only other baby known to have survived after being born to a mother with Ebola. Nubia was born in an Ebola treatment centre in Guinea in 2015, after receiving three experimental drugs, including remdesivir, which MSF now gives to pregnant women in DRC. Her mother died hours after she was born.

Sylvana has been tested twice for the disease and the results have been negative. However, there is a 21-day incubation period for Ebola, and her progress will continue to be monitored. In another recent case in DRC, a baby born to a mother cured of Ebola is understood to have tested negative at birth only to become positive six days later. The child subsequently died.

Pregnant women who are treated in MSF clinics in DRC are given remdesivir, one of several experimental drugs used in the current epidemic. “It’s a very small molecule and we assume that it will transfer more easily to the placenta,” said Caluwaert, who added that it is believed the virus accumulates in amniotic fluid.

It is not clear what treatment was given to Sylvana, who was treated by staff from the NGO Alima.

The survival rate for children aged one year and under is 17%, according to data collected in MSF during the west Africa epidemic. The survival rate for pregnant women was roughly 45%. However, this figure should be treated with caution, since pregnancy tests were not routinely carried out in the early stages of the outbreak or where women were at immediate risk of death. Another study suggested a mortality rate of 80-90% for pregnant women.

Women who are pregnant or lactating are currently denied the experimental vaccine for Ebola, a policy described as “utterly indefensible” by health experts.

The decision, which was made by the DRC health ministry and echoes WHO recommendations, is based on concerns that the vaccine may cause complications in unborn children and babies.

So far in DRC, more than 56,866 people have been vaccinated. The vaccine, made by Merck, is used to immunise a “ring” of contacts of any person who becomes ill.