Our Data Powerhouse has previously investigated the impact of COVID-19 on the incidence of RSV and influenza. In addition, the group is working on a project on pneumococcal disease in Danish children and adolescents.

​Publications

Safety of pertussis vaccination in pregnancy and effectiveness in infants: a Danish national cohort study 2019–2023, Kildegaard H, Jensen A, Andersen P.H.S, Dalby T, Gram M.G, Lidegaard Ø, Stensballe L.G (2025) ​

In this nationwide study we assessed the safety and effectiveness of pertussis vaccination during pregnancy in Denmark during 2019-2023. We found that vaccination of  pregnant women reduced the risk of laboratory confirmed pertussis in infants less than 3 months of age with 72% while also reducing the risk of pertussis-related hospital contacts. We found no increased risk of severe adverse events in neither the ​mother nor the child, including preterm premature rupture of membrane (PPROM), preterm birth, stillbirth, or neonatal intensive care. The results support that pertussis vaccination in pregnancy is a safe and effective strategy to protect infants against pertussis during their first months of life. ​

Impact of COVID-19 on testing, positive cases, patient characteristics, and hospital contacts for respiratory syncytial virus, influenza, and pneumococcus in Danish children, Jensen A, Stensballe LG (2025) 

The study assessed the occurrence of respiratory infections such as respiratory syncytial virus (RSV), influenza, and pneumococcal disease in Danish children and adolescents (ages 0-17) from 2012 to 2022, and how COVID-19-related measures affected the development. During the lockdown, the number of RSV cases to an absolute and sustained zero. However, as restrictions were lifted, the number of cases increased significantly – even outside the typical season for the virus. 

Over the study period, testing behavior changed, with a substantial increase in the number of tests for all three pathogens. For instance, during peak periods, there were twice as many daily tests for RSV and influenza immediately after the pandemic compared to the period before. Testing also increasingly included children without underlying chronic disease. Finally, there were periods when a lower proportion of positive tests for RSV and influenza were linked to hospital contacts, especially longer hospital admissions. This raises the question of whether the interventions are appropriately tailored to children with the greatest need for care.
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