Reacción a "Reactions: Study says children born in October are less likely to get the flu"

Influenza vaccination is particularly important in young children due to the high risk of severe infections requiring hospital admission. Vaccination is recommended during the months of September to October to try to achieve adequate immunisation for the peak of influenza infections. 

In this paper, the authors attempt to shed light on the best time of year for vaccination in order to achieve better vaccination efficacy. 

The authors reject the idea of measuring vaccine efficacy through assays such as the detection and quantification of neutralising antibodies, and therefore present an approach based on the quantification of the number of hospital admissions and the severity of symptoms developed by vaccinated children included in the study. 

They selected more than 800,000 children aged two to five years in the United States, born between August and December, who received the flu vaccine during their annual visit to the paediatrician between 2011 and 2018. 

At these ages, the annual paediatric check-up usually coincides with the month of the child's birth, so the authors were able to observe that children born in October tend to receive their annual flu vaccination later than children born in August and earlier than those born in December. In addition, children born in October were more likely to be vaccinated during October and less likely than other children in the study to be diagnosed with influenza during that season. 

This is a semi-experimental study, but it supports the current recommendation that children should be vaccinated in October, preceding the flu season.