Side effects associated with the vaccine are:
Very common (affecting more than 1 in 10 people)
- runny or stuffy nose
- loss of appetite
- feeling generally unwell
Common (affecting up to 1 in 10 people):
- high temperature (fever)
- aching muscles
Uncommon (affecting up to 1 in 100 people):
- nose bleeds (it is thought these are unlikely to be caused by the vaccine itself)
- allergic reactions
Additional information about vaccine side effects, anaphylaxis and adverse reactions can be found here.
There is no evidence that healthy unvaccinated people can catch flu from the nasal flu spray (either from airborne spray droplets in the room where the vaccine is given, or from vaccinated individuals ‘shedding’ the virus).
It is known that vaccinated children shed the virus for a few days after vaccination (through sneezing or coughing). However, the vaccine virus is weakened, and so it is much less able to spread from person to person than flu viruses that circulate during the flu season, and it cannot grow inside the body. The amount of virus that children shed is normally below the levels needed to pass on infection to others. The virus does not survive for long outside the body.
It is therefore not necessary for children to be excluded from school during the period when the vaccine is being given. The only exception is the very small number of children who are extremely immunocompromised (for example, those who have just had a bone marrow transplant). These children are usually advised not to attend school anyway, because of the higher risk of being in contact with infections that circulate in schools.
The nasal flu spray should not be given to anyone who is severely immunodeficient (so that their immune system cannot control viral infections in the normal way) due to a medical condition or treatment with an immunosuppressive therapy such as:
- Acute and chronic leukaemias while on chemotherapy
- Lymphoma while on chemotherapy
- Immunosuppressed individuals with HIV infection whose immune system is compromised, usually because they are not on highly active antiretroviral therapy (HAART)
- Individuals with inheritated cellular immune deficiencies
- Individuals on high dose corticosteroids (prednisolone at least 2mg/kg/day for a week or 1mg/kg/day for a month or equivalent)
- Individuals on other immunosuppressive drugs, including some monoclonal antibodies
This is because the weakened viruses in the vaccine could replicate too much and cause infection.
Children who have been vaccinated with the nasal spray should avoid close contact with people who have very severely weakened immune systems (for example, bone marrow transplant patients requiring isolation in a protective environment) for about two weeks following vaccination. If it is not possible for a child to avoid contact with someone who is severely immunosuppressed (for example, because they live in the same house), the child should not receive the nasal flu vaccine. It may be possible for them to have the inactivated flu vaccine instead.