A study published in Nature Microbiology found that children born by C-section were up to 2.6 times more likely to have an ineffective measles vaccine compared to children born naturally. The researchers attributed this to the different development of gut microbiome in infants born by C-section, which could impact immune system response. The study emphasizes the importance of ensuring that children born by C-section receive their second measles jab to protect against the disease.