Imagine a child recovering from a bad stomach bug, only to face a new battle with a lung infection shortly after. This study looked at 9,116 children between 6 and 35 months old across seven sites in Asia, Africa, and South America. The researchers wanted to know how often these kids caught a respiratory tract infection within three months of having medically-attended diarrhea. They found that 3.8% of all children in this group developed a new respiratory infection during that time.
The risk was not the same for every child. Children aged 12 to 23 months faced an 8.7% chance of infection. Those who were undernourished saw the risk jump to 16.1%. Unvaccinated children had a 4.0% risk, and those living in poor sanitation settings faced a 4.1% risk. The study did not report any safety issues or side effects from the diarrhea itself, as it was an observational review of existing medical records.
However, we must be careful with what we conclude. When the researchers adjusted for age, sex, and study site, the link between vaccination status and infection was no longer statistically significant. This means we cannot say for sure that being unvaccinated directly caused the higher infection rates seen in the raw numbers. The data on this specific burden in low-income countries is currently limited, so we should not overstate these findings as absolute proof of cause and effect.