“We were surprised to see viral infections occur so early in life, and go mostly unnoticed, probably because the infants’ immune system is in what is known as a state of tolerance after birth,” said researcher Debby Bogaert. “Despite this, these infections seem to affect a normal immune development, which is important to know.
“Only from birth onwards will an infant start to develop its microbiome. Limiting the number of viral encounters in those first days to weeks of life might be essential for a healthy immune and microbiome development, and consequently long-term respiratory health.”
Assessing infants’ long-term health risks
For the study, the researchers analyzed data from 114 babies enrolled in the Microbiome Utrecht Infant Study. The team evaluated samples taken from the infants’ nasal cavities to better understand how potential infections in their earliest days of life impact long-term health outcomes.
Ultimately, the researchers learned that infants had a higher risk for future infections when they contracted viruses in their first days of life. The team explained that these early life viruses go undetected most of the time because babies don’t show any symptoms of being sick.
However, these sicknesses are causing damage to the immune system. The study findings showed that early life viruses impacted immune system genes that create cells to protect against future viruses. These changes were associated with a greater inflammatory response throughout the immune system, which in turn makes the infants more vulnerable to future infections.
The researchers also found that these infections during early infancy affected the infants’ microbiome. Over time, these viruses increased the risk of potentially harmful microbes multiplying throughout the body.
Moving forward, the researchers hope more work is done in this area to better understand how infants’ early exposure to certain viruses can affect their long-term health.
“Although further work will be needed to confirm the causality of our findings, the data from thai study indicate that early-life encounters with respiratory viruses – especially during the first days of life – may set the tone for subsequent non-beneficial host-microbe interactions, which are related to an infection risk and possibly long-term respiratory health.”