1. A liposome within which an RNA encoding an immunogen of interest is encapsulated, wherein the liposome contains at least one lipid that includes at least one lipid that is attached to the polyethylene glycol component, so that the polyethylene glycol component is present on the outer surface of the liposome, where the average molecular the mass of the polyethylene glycol component is higher than 3 kDa, but less than 11 kDa. 2. The liposome according to claim 1, containing PEG-DMG and / or a lipid of the formula (X): where Z is a component of the hydrophilic head group selected from PEG and polymers based on poly (oxazoline), poly (ethylene oxide), poly (vinyl alcohol), poly (glycerol), poly (N-vinylpyrrolidone), poly [N- (2-hydroxypropyl) methacrylamide] and poly (amino acids), wherein the polymer may be linear or branched, and wherein the polymer may be optionally substituted； Z is polymerized by n subunits； n denotes the number average polymerization degree from 10 to 200 Z units (and can optimize for different groups Z)； L denotes an optionally substituted C 1-6 alkylene or C 1 heteroalkylene linker, including zero, one or two of an ether (e.g., -O-), an ester (e.g., C (O) O-), a succinate (e.g., - O (O) C-CH-CH-C (O) O-)), carbamate (e.g. -OC (O) -NR′-), carbonate (e.g. -OC (O) O-), (e.g. -NRC (O) NR′-), amine (e.g. -NR′-), amide (e.g. -C (O) NR'-), imine (e.g. -C (NR ') -), thioether (e.g. , -S-), xanthan (e.g., -OC (S) S-) and phosphodiester (e.g., -OR (O) O-), where R ′ is independently selected from -H, -NH-, -NH, -O -, -S-, phosphate or optionally substituted alkylene； X and X are independently selected from a carbon or heteroatom selected from - NH-, -O-, -S- or phosphate； A and1. Липосома, внутри которой инкапсулирована РНК, кодирующая представляющий интерес иммуноген, где липосома содержит по меньшей мере один липид, который включает по меньшей мере один липид, который присоединен к полиэтиленгликолевой составляющей, так что полиэтиленгликолевая соста
