Tretra Live attenuated Vaccine (Sheffield Teaching Hospitals NHS Foundation Trust)

Influenza ('flu) can cause severe infections, especially in people with weakened immune systems such as those with HIV. For this reason, yearly vaccination is recommended with the standard 'inactivated' influenza vaccine to try and prevent infections in these populations. It is also recommended in all health care workers, to help prevent the spread of influenza within healthcare settings. However, having HIV infection may mean vaccines work less well in some people and the investigators do not completely understand why. An alternative to the standard 'inactivated' annual influenza vaccine is the 'live attenuated influenza vaccine' (LAIV), which means it consists of weakened versions of the influenza virus.
Unlike the standard vaccine, which is given by injection, LAIV is a spray that is given into each nostril. It is now given to children in the UK in preference to the standard vaccine as it results in greater protection from influenza. In some other countries, like the USA, adults are also given LAIV, where it seems to work just as well as the standard vaccine. A few studies in the past have shown that LAIV is safe and effective in HIVinfected children and adults. The investigators want to give LAIV to HIVinfected and HIV negative individuals, to try to find out new information about how HIV infection may change the way in which people respond to vaccines. The investigators will do this by comparing both the early genetic response to the vaccines and later responses from cells specifically targeted to fight influenza ('Tcells'), in these groups. In the long term, the investigators hope that this will lead to designing new ways of improving the response to vaccines in HIVinfected people. As LAIV is given into each nostril, rather than an injection, the investigators also want to see if LAIV results in Tcells in the lung that are specifically targeted to fight influenza