The nasal flu spray has also been used widely in the US since 2007 in children from the age of 2 upwards. It has a good safety profile. In 2016, research from the US showed that the nasal flu vaccine was no longer working well in children against one of the strains in the vaccine (influenza A(H1N1)). As a result the nasal flu spray was not recommended for use in the US during the 2016-17 and 2017-18 flu seasons (see our
blog piece from September 2016).
However, research in the UK and in Finland showed that in these two countries the nasal flu spray was still working well against influenza A(H1N1). It is not known why there is a difference between the US research and the UK and Finnish research, but the UK is continuing to monitor this. There is a
review from August 2017 which looks at the issues in more detail.
For 2018-19 and 2019-20 seasons the vaccine manufacturers have used a different version of the influenza A(H1N1) strain in the vaccine. This is expected to be more effective against influenza A(H1N1), and the Centers for Disease Control and Prevention in the US are now once again
recommending the nasal flu spray for use in children in the 2018-19 flu season.
Source:
https://vk.ovg.ox.ac.uk/vk/nasal-flu-vaccine