No 27 - 2021

Unusual occurrence of RS virus this summer

Unusual occurrence of RS virus this summer

We are currently recording an unusual summer occurrence of RS virus in Denmark. Treating physicians are encouraged to pay attention to this diagnosis.

RS virus causes airway infection and may affect anyone. However, infants < 2 years of age are at special risk of serious infection, which frequently causes difficulty breathing often requiring admission to hospital .

During the COVID-19 epidemic, several of the common airway infections have been absent, including influenza and RS virus. Presumably, the low occurrence of these infections is owed to the many social restrictions and hygiene measures introduced to limit COVID-19. RS virus normally occurs frequently in the winter season, but during the COVID-19 restrictions, only few cases of RS virus were recorded in Denmark .

However, in recent weeks, an increasing number of RS virus cases has been recorded in Denmark, see Table 1. Other countries, including Australia and the USA have also reported an increasing occurrence of RS virus following the loosening of COVID-19 restrictions.


In Denmark, recording RS virus cases during the summer months is unusual and we therefore encourage treating physicians to pay special attention to the occurrence of RS virus in patients with airway infection. On clinical suspicion of RS virus, we recommend ensuring that the relevant microbiological tests are made to confirm of dispel the diagnosis.

Ramona Trebbien, Virus and Microbiological Special Diagnostics, Lasse S. Vestergaard, Infectious Disease Epidemiology and Prevention.