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Column originally published Jan 30, 2001

RSV Infection Can Make Premature Babies Very Sick

Question: My sister delivered a very premature baby three months ago. She was on a respirator for several weeks. After she came home, she was still connected to an oxygen tank. This baby is very tiny, although she is nursing and growing well. My sister told me that her daughter gets a vaccine once a month against a virus called RSV. Last week my son has a cold and she wouldn’t let us go to visit her. She said that she is afraid her daughter will catch the RSV. Is she being over-protective?


Your sister is not over-protective. She is doing everything right for her premature daughter. Let me explain to you about this virus so that you have better understanding about the danger of RSV infection in premature babies.

Respiratory Syncytial Virus (RSV) infection is very common in North America between November and April every year. The virus is spread mostly by children, in school, kindergarten, or daycare. Adults do pick up this virus infection from children.

RSV is spread through secretions from the nose. Between two days to one week after infection, the virus will multiply in the nose and throat, and produce a lot of clear running nose. There may not be too much fever. Most children will have a little congested cough, and the whole illness may last a few days only. When the infection is mild, there is no difference between RSV infection and common cold.

Children under two years of age can develop a more serious condition called bronchiolitis. Instead of getting better after a few days, these children will get worse with increasing cough. Wheezing, which is a high pitch breathing noise, can be detected by the doctors, and sometimes even by parents without using a stethoscope.

These children with bronchiolitis can get very sick. They may have difficulty breathing, and their colour can turn very pale. Some also have trouble drinking or eating. Some of these children have to be admitted to hospital for treatment.

RSV can trigger an asthma attack in children who have asthma. After getting what seems to be a cold for one or two days, these children can develop severe coughing and wheezing, and may end up in hospital with an asthma attack.

Sometimes it is difficulty to tell whether a young child has bronchiolitis from RSV infection or an asthma attack. Very often, doctors have to treat these children like asthma, and wait to see whether coughing and wheezing return with future colds.

RSV infection in very small premature babies poses a particular risk. Many of these babies have very immature lungs and require the respirators to help them breathe. Some of these infants develop a lung condition called BPD (broncho-pulmonary dysplasia) and may require home-oxygen for weeks or months.

These little infants are very susceptible to severe RSV infection. Instead of a mild cold, the illness quickly progresses to severe lung congestion, coughing, wheezing, and not infrequently death. That is why their parents have to be very vigilant in preventing RSV infection.

At the present time, there is no effective treatment against Respiratory Syncytial Virus. The only thing doctors have to offer in the hospital is to support breathing, but nothing to kill the virus.

There is very active research in trying to prevent RSV infection. An “active” vaccine, one that stimulates the body’s own immune system to produce antibodies, like hepatitis vaccine, is still under investigation.

The one that your niece is getting is a “passive” vaccine. Passive vaccines are antibodies that can prevent infection as soon as they are given. This particular RSV vaccine, called Palivizumab (what a difficult name, also known as Synagis), has been licensed in Canada for about two years. It was produced by immunizing mice with RSV. The purified antibodies from these mice were then modified, so that they became very close to the human kind of antibodies. This modification is a very important step to prevent reaction, since human and mouse antibodies are different.

Research had shown that this RSV vaccine, produced in mice, was very effective in preventing RSV infection in very young infants. The vaccine is given by injection into the muscle once a month, usually between October / November until April / May, when RSV season is usually over.

As you can see, your sister is definitely not over-reacting or over-protecting her little girl. She is well educated by the nurses and doctors who looked after her baby. She knows that RSV can cause serious infection, and the best way to prevent it is to avoid children (and adults) who are sick, and may carry the virus. Getting RSV vaccine can reduce the chance of infection and serious complications.

Just be patient with your sister. When your son (and anyone else in your family) recovers completely, your family can feel comfortable to visit her. When you are there, it is a good practice to wash your hands before holding the baby. This will reduce the chance of passing germs to her.

Hopefully, within a few months, her daughter can come off oxygen, and she will be less likely to suffer from serious RSV infection next year.