Covid-19: in Singapore, a baby is born with antibodies

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Several researchers have suggested that some children have developed immunity against Covid-19 without being infected with the virus.

Since the beginning of the health crisis, children often have mild forms of Covid-19. In the vast majority of cases, the youngest are asymptomatic when affected by the virus. In early November, two new studies suggested that children develop immunity to the coronavirus without contracting it. The first investigation, published in the journal Science, notably observed the presence of antibodies in almost 44% of children who were not infected. But that is not all: in Singapore, a baby was born with antibodies against Covid-19.

Baby born with antibodies against Covid-19

"We do not yet know if a pregnant woman with Covid-19 can transmit the virus to the fetus during pregnancy or to the baby during delivery. To date, the presence of the virus has not been observed in samples of fluid in which the patient bathes fetus or breast milk, "according to the World Health Organization (WHO).

The case of a pregnant woman living in Singapore offers some answers. This 31-year-old girl was affected by Covid-19 at 10 weeks of pregnancy. She became infected last March while traveling in Europe, along with her 58-year-old mother and two-year-old daughter. Her father and husband, who were also on the trip, were not infected.

The young woman contracted a mild form of the disease, but her pregnancy was difficult because her mother was severely affected by Covid-19: she was hospitalized for four months and spent 29 days in intensive care.

When she gave birth on November 7, the young mother, however, had good news: her newborn baby, Aldrin, had not contracted Covid-19. But that is not all: he had even developed antibodies against the coronavirus. "It is very interesting. Her pediatrician said that my antibodies against Covid-19 had disappeared, but Aldrin has antibodies against the disease. My doctor suspects that I transferred my antibodies to her during pregnancy," the young woman explains in the Straits Times.

The boy who developed strong immunity to Covid-19

Last March, an Australian family went to a wedding. Upon returning from the event, the parents developed a cough, nasal congestion, fever, and headache. With two of his children, they tested positive for Covid-19. Researchers at the Murdoch University Research Institute (MCRI) in Victoria, Australia, recruited the family to conduct a case study. They found that the younger brother, 5 years old, had tested negative for the virus and had never had symptoms suggestive of the disease. The scientists also noted that he had developed strong immunity to the virus.

However, the little boy did not respect the rules of distance with his parents or his siblings. He had even slept with his parents when they were sick. During the study, published in the journal Nature, clinical, virological, cellular, immune and serological tests were performed on family members. Specific antibodies against SARS-CoV-2 have been detected in saliva and serological tests of the parents and the three children.

"The youngest child, who showed no symptoms, had the strongest antibody response. Despite the active response of immune cells in all children, the levels of cytokines, molecular messengers in the blood that can trigger an inflammatory reaction , she remained weak. This was consistent with her mild or absent symptoms, "said MCRIs Dr. Melanie Neeland.

Is there cross immunity in children?

Researchers from the Pasteur Institute, Inserm, AP-HP and the University of Paris have also studied the issue of cross-immunity in children. This hypothesis is based on the idea that having infected us with another coronavirus can make us immune to Covid-19. As a reminder, the coronavirus family is made up of many viruses, most of which are responsible for a simple cold. According to this study, published on the scientific pre-publication site MedRxiv, 40 to 60% of the population would be immune to Covid-19 thanks to past contamination with another coronavirus.

To determine whether an infection transmitted to another coronavirus impacted immunity to Sars-CoV-2, the researchers analyzed antibody levels against the four seasonal coronaviruses (NL63, HKU1, 229E, OC43) in 739 children ages 0 to 18. years.

They were separated into three groups: the children in the first group had positive serology, which shows that they had been affected by Covid-19 and that they had developed antibodies, although they had few or no symptoms. The second group consisted of participants with symptoms suggesting multisystem inflammatory syndrome in children (MIS-C), a rare disease associated with Covid-19, which se resembles Kawasaki disease. The children in the third group, meanwhile, had negative serology, a sign that they had never been affected by Covid-19.

As a result, all of the participants had more or less similar antibody levels against the four seasonal coronaviruses. The level of anti-Sars-CoV-2 antibodies was not significantly different in children who had developed a coronavirus infection. Therefore, the researchers concluded that a past infection with a seasonal coronavirus did not prevent children from being affected by Covid-19.

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