It’s deep winter again, and in the PICU that means cases of severe infection from respiratory syncytial virus, or RSV, are starting to come in. This virus is the major cause of periodic outbreaks of lower respiratory tract (meaning in the lungs) illness in young children. It is extremely common and highly infectious: its attack rate, meaning the chances of a susceptible person getting the infection if exposed to a case, is among the highest of any virus. Estimates are that as many as 125,000 infants each year are hospitalized with RSV, with many, many more infected less severely. The peak age for those children needing a hospital is between two and five months. It is so common that by early childhood virtually all of us have been infected at least once.
If it’s so common, why don’t we become immune to it? And we don’t become immune — even adults are frequently reinfected, especially adults who spend time with young children. Immunologists don’t know the answer to that question. For one thing, our immune systems may even be involved somehow in causing some of the manifestations of RSV. The problem is not, as with common cold viruses, that there are so many varieties of RSV; there are only two forms of RSV, and getting infected with either of them doesn’t mean you won’t get infected again within a couple of years. So whatever immunity we get from infection is very short-lived. That being the case, it isn’t surprising that efforts to develop a vaccine have been unsuccessful.
Much of the time RSV causes the symptoms of a cold — cough, runny nose, sometimes a low-grade fever. But in very young children, particularly infants, RSV can cause severe pneumonia or bronchiolitis. The latter disorder is an inflammation of the tiniest of the lung’s air tubes, or bronchioles. This inflammation blocks off the little tubes, making it difficult for air to get in, or most characteristically, to get the air out. Babies with severe RSV often need oxygen, some need mechanical ventilators to breathe for them, and a few die. Over the years I have cared for hundreds of children with severe RSV infection in the PICU. It is so common that, during an outbreak, PICUs often run out of available beds.
As for most viral infections, there is no specific treatment for RSV — therapy is, as we say, “supportive.” This means that we use oxygen, frequent suctioning of the child’s respiratory secretions, and, if needed, a mechanical ventilator to support the child while the disease runs its course.
Nearly all children are equally susceptible to getting RSV, but some children are especially prone to develop severe cases when they get it. Former premature infants and those with significant underlying lung problems are especially at risk. For these infants we do have an injection of an anti-RSV antibody that can help; it doesn’t prevent them from getting it so much as make their cases less severe if they do. Unfortunately the injection doesn’t last very long — it needs to be given every month.
How can you prevent your child from getting RSV? That is a difficult question, and a better one is how to postpone your child’s getting it until they are out of the most high-risk age group for severe disease. The only way is to reduce or eliminate exposure to sick children during the peak season, which is usually winter to early spring. It also helps simply to have everyone wash their hands before holding your child.
You can read much more about RSV here.