RSV is linked to childhood asthma – but we can’t yet say one causes the other

As winter approaches in Australia, respiratory viruses are in all places. One of the important culprits is the RSV virus, which has caused over 145,000 infections across the country this yr. Most of them are amongst children under five.

RSV is the leading reason for bronchiolitis and pneumonia (each chest infections) in young children. Every yr no less than one in 200 children children under five are hospitalized with RSV in Australia. Babies lower than six monthsand particularly children under three months of age, are most in danger.

The RSV virus infects respiratory tract and lungswhich causes the mucus in the respiratory tract to turn into very sticky. Young children may experience coughing, wheezing, difficulty respiratory and feeding problems.

Studies indicate that severe RSV infection in infancy can also increase the risk children with asthma. So what evidence is there linking RSV to asthma? And why might this link exist?

Relationship or cause-and-effect relationship?

Asthma is a chronic lung disease that affects: 11% Australians. People with asthma often have difficulty respiratory, coughing, and wheezing. This happens because their airways turn into temporarily narrower, often due to triggers (for instance, viral infections, dust, or pollen). Asthma often begins as wheezing in preschool. But for some people, it begins in maturity.

When we speak about RSV and asthma, it is essential to consider the differences between association and causation. An association occurs when two events often occur together (for instance, smoking and drinking coffee), while a causal relationship occurs when we know that one may cause the other (for instance, smoking and lung cancer). While the association between RSV and asthma is well-established, a causal relationship it has not been proven yet.

To prove a causal relationship, certain criteria should be met. These include a temporal relationship (on this case, RSV infection must occur before asthma) and a plausible explanation (a biological mechanism).

Some evidence suggests that RSV infections change the developing cells in the airways of infants and young children. This could mean that the protective or barrier function of the lining of the airways is altered, predisposing a toddler to turn into sensitized to allergens — when their immune system makes antibodies to something they encounter, similar to grass or dust.

Allergen sensitization is a major risk factor for asthma, so severe RSV infection may contribute to the development of asthma through sensitization to common environmental allergens. This is a possible biological mechanism, but we still need more research to confirm this.

Several studies show an association between severe RSV infection and recurrent wheezing and asthma in later childhood.

But what comes first? one studyChildren under 12 months of age who developed RSV bronchiolitis were followed for six years. Almost half (48%) were diagnosed with asthma before their seventh birthday.

Similarly in one other testChildren hospitalized for RSV infection before the age of two were more likely to develop asthma by the age of 18 than those that weren’t hospitalized.

However, the researchers who conducted twin study concluded that the data were more likely to indicate reverse causation. That is, children with a predisposition to asthma were more likely to develop RSV requiring hospitalization.

We could also be closer to the answer

The pendulum could also be swinging towards causality. Recent findings from South Africa Birth Cohort Study showed that severe RSV infections were related to each recurrent wheezing and subsequent impairment of lung function.

Some prior examination Studies conducted by this group showed that hospitalization for any respiratory infection, and particularly for RSV, was related to recurrent respiratory infections and wheezing. Recurrent wheezing and decreased lung function are predictors of future asthma.

Other last examination Studies of greater than 1,700 children in the United States have shown that avoiding RSV infection in infancy can prevent up to 15% of childhood asthma cases.

Recently, the possibility of vaccinating moms and using monoclonal antibodies to prevent RSV infection has emerged, which is able to probably help answer this query once and for all.

Earlier this yr, nirsewimab (a long-acting monoclonal antibody) became available for infants and young children through state programs in Western Australia, Queensland AND New South Wales. Nirsevimab works barely in another way than the vaccine, but is similarly administered as an injection.

In addition, the RSV vaccine Abrysvo was licensed in Australia this yr to be used while pregnant to protect the baby after birth. It is available to pregnant women to buy privately on prescription from a health care provider, while South Australia recently announced it is going to provide Abrysvo free to pregnant women next yr.

With these measures, hopefully we will see a discount in RSV at a population level in the coming years. If we see a discount in asthma at the same time, this will likely finally answer the query of causality.

Protecting children and communities

Although it is still not known whether RSV causes asthma, RSV and other viral infections will be especially problematic for individuals who have already got asthma. In each cases adults in children with asthma, respiratory diseases of viral origin can have a more severe course and cause an exacerbation asthma symptoms.

RSV It is spread through coughing, sneezing, and shut contact. There are many other viruses that spread in similar ways. Parents will help keep their children and others healthy by encouraging children to cover their mouths and noses when coughing or sneezing and to wash their hands recurrently.

Ensuring that children don’t go to school, daycare, or other children once they are sick helps prevent the spread of many viruses, including RSV. Finally, staying up to date on vaccinations and getting a flu shot yearly could make an enormous difference in our health and the health of those around us.