Doctors advise against kissing newborn babies.

According to Dr. Karan Rajan of the UK's National Health Service (NHS), the mouth and face of adults contain millions of bacteria and viruses, which can easily be transmitted to newborns. The immune system of adults is complete and can fight off external pathogens. However, the immune system of newborns is still in the development stage, "learning" to fight against foreign agents. Although some antibodies have formed, newborns are still susceptible to dangerous diseases.

Bacteria or viruses from strangers can cross the blood-brain barrier, leading to life-threatening complications. Dr. Rajan’s advice comes after a viral video showed a woman wrapping plastic wrap around her face to kiss her newborn granddaughter. He said this was not enough, as tiny particles and even dirt could still be stuck on the plastic. He said avoiding kissing children altogether would be more effective.

"The immune system of newborns is immature and susceptible to infection. Even common illnesses that have mild symptoms in adults can be life-threatening to newborns," said Dr. Raj.

He even suggests that family and friends wait two to three months until the baby's immune system is stronger before visiting. Being close to parents is important for a child's development, and the risk of parents carrying germs that the child has not been exposed to is lower. Therefore, parents can occasionally kiss their children.

Experts have warned that some viral diseases can be transmitted through kissing, leading to serious complications such as pneumonia in young children. Some diseases affect children much more severely, such as cold sores caused by the herpes simplex virus, which often “clears up” in adults without the need for creams, said Muriel Meso, MD, a pediatrician and endocrinologist at Portland Hospital. In infants, however, the virus can spread to the brain, causing seizures and spinal cord damage. Similarly, chickenpox can cause dehydration and inflammation of the brain and other organs, including the kidneys.

“If left untreated, children can develop complications such as pneumonia and other serious secondary infections,” says Dr. Meso.