SEASONAL INFLUENZA VACCINE CAPABLE OF INDUCING VIRUS-SPECIFIC ANTIBODY INTO NASAL CAVITY

Abstract

Provided is a seasonal influenza vaccine having a higher efficacy than a split vaccine. A seasonal influenza vaccine which induces virus-specific antibodies in the nasal mucosa, comprises inactivated whole influenza virus particles as an active ingredient, and is to be administered intradermally at dose per administration of 15 μg HA or more per strain as antigen.

Claims

1. An influenza vaccine composition comprising: inactivated whole influenza virus particles derived from one or more influenza virus strains as an active ingredient, wherein each dose of the influenza vaccine composition comprises the inactivated whole influenza virus particles at a concentration to provide 15 μg hemagglutinin or more per influenza virus strain.

2. The vaccine composition according to claim 1, wherein the inactivated whole influenza virus particles are derived from an influenza A virus strain and/or an influenza B virus strain.

3. The vaccine composition according to claim 2, wherein the inactivated whole influenza virus particles are derived from both an influenza A virus strain and an influenza B virus strain.

4. The vaccine composition according to claim 1, which does not comprise an adjuvant.

5. The vaccine composition according to claim 3, which is a quadrivalent vaccine comprising inactivated whole influenza virus particles derived from two influenza A virus strains and two influenza B virus strains.

6. (canceled)

7. The vaccine composition according to clams 5, wherein the two influenza A virus strains are A/H1N1 and A/H3N2 subtypes, and the two influenza B virus strains are B/Victoria and B/Yamagata lineages.

8. A method of administering an influenza vaccine, comprising: intradermally administering a dose of the influenza vaccine composition of claim 1 to a subject.

9. The method according to claim 8 wherein the dose is administered with an intradermal needle or a micro needle microneedle.

10. The method of claim 8, wherein the influenza vaccine is a seasonal influenza vaccine.

11. The method of claim 9, wherein a protruding length of the needle tube of the intradermal needle or the microneedle is in a range of 1.0-1.5 min.

12. The method of claim 8, wherein the administration is performed with an intradermal administration device comprising three needle tubes.

13. The method of claim 8, wherein the vaccine administered as multiple doses at an interval of 1 to 4 weeks.

14. The method of claim 8, wherein each dose has a volume in a range of 0.1 to 0.5 mL.

15. The method of claim 8, wherein the subject is a human.

16. The method of claim 8, wherein the administering induces virus-specific antibodies in a nasal mucosa of the subject.

17. The method of claim 16, wherein a neutralizing antibody titer produced against the virus-specific antibodies in the nasal mucosa is 80 or more as measured by assessing the inhibitory activity on the cytotoxicity of the virus against MDCK cells.

18. The method of claim 17, wherein the neutralizing antibody titer is 160 or more.

19. The method of claim 17, wherein the neutralizing antibody titer is measured 21 days after administering a second dose, and wherein the second dose is administered 21 days after administering a first dose to the subject

20. The method of claim 16, wherein the inactivated whole influenza virus particles are derived from both an influenza A virus strain and an influenza B virus strain, and wherein the antibodies are specific against both the influenza A virus strain and the influenza B virus strain.

21. The method of claim 17, wherein the neutralizing antibody titer is at least two times greater than a comparative dose administered subcutaneously at the same frequency in a substantially similar subject, and wherein the comparative dose has the same composition or instead comprises a split influenza antigen at the same concentration of hemagglutinin of the dose.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0021] [FIG. 1] Serum HI antibody titer against B/Phuket/3073/2013 strain on subcutaneous administration of a vaccine.

[0022] [FIG. 2] IgG titer of nasal lavage fluid against B/Phuket/3073/2013 strain on subcutaneous administration of the vaccine.

[0023] [FIG. 3] Virus content in nasal lavage fluid 3 days after virus inoculation.

[0024] [FIG. 4A] IgG titer of nasal lavage fluid against A/Singapore/GP1908/2015 strain.

[0025] [FIG. 4B] IgG titer of nasal lavage fluid against A/Singapore/INFIMH-16-0019/2016 strain.

[0026] [FIG. 4C] IgG titer of nasal lavage fluid against B/Phuket/3073/2013 strain.

[0027] [FIG. 4D] IgG titer of nasal lavage fluid against B/Maryland/15/2016 strain.

[0028] [FIG. 5] Neutralizing antibody titer of nasal lavage fluid against A/Singapore/GP1908/2015 strain.

DETAILED DESCRIPTION OF THE INVENTION

[0029] The following describes in detail the preferred embodiments of the present invention. However, the present invention is not limited to the following embodiments.

[0030] In the present invention, “seasonal influenza vaccine” means a vaccine for seasonal influenza, which contains at least an antigen of either the seasonal influenza A virus or influenza B virus. That is, the seasonal influenza vaccine of the present invention may be a monovalent vaccine containing only one of the seasonal influenza A virus or influenza B virus, or a multivalent vaccine containing both of them, but preferably, it is a trivalent or higher valent vaccine containing at least three or more influenza virus strains, for example, two influenza A virus strains and one or two influenza B virus strains, and preferably includes a quadrivalent vaccine. More preferably, it includes a quadrivalent vaccine containing two A strains (A/H1N1 and A/H3N2 subtypes) and two B strains (B/Victoria and B/Yamagata lineages).

[0031] In the present invention, when using the term “influenza virus”, it refers to the seasonal influenza A virus or influenza B virus, or both. Influenza virus also includes all currently known subtypes, as well as subtypes to be isolated and identified in the future.

[0032] The influenza virus strain used in the preparation of the vaccine of the present invention may be a strain isolated from an infected animal or patient, or a recombinant virus established in cultured cells by genetic engineering.

[0033] “Inactivated whole influenza virus particle”, the antigen of the seasonal influenza vaccine of the present invention, refers to a virus particle which is obtained by culturing a seasonal influenza virus while retaining the morphology of the virus, and has been subjected to an inactivation treatment.

[0034] The inactivated whole influenza virus particle of the present invention can be prepared using the embryonated chicken egg method or cell culture method.

[0035] The “embryonated chicken egg method” refers to a method in which a virus strain is inoculated into incubated embryonated chicken eggs and cultured, and then the virus suspension is clarified, concentrated, purified, and inactivated to obtain a virus solution containing virus particles. The “cell culture method” refers to a method in which a virus strain is inoculated into cultured cells and cultured, and then a virus solution containing virus particles is obtained from the culture supernatant in the same way as the above embryonated chicken egg method.

[0036] Here, the culture is performed at 30 to 37° C. for about 1 to 7 days, preferably at 33 to 35° C. for about 2 days after inoculation of the influenza virus strain. After the culture is completed, the virus suspension (infected allantoic fluid or infected cell culture supernatant) is collected, and centrifugation or filtration is performed for clarification. Then, a barium salt adsorption-elution reaction or ultrafiltration is performed for concentration. The virus purification can be performed by using ultracentrifugation such as sucrose density gradient centrifugation or other means such as liquid chromatography.

[0037] The purified virus solution is subjected to an inactivation treatment. Examples of the virus inactivation method include formalin treatment, ultraviolet irradiation, and treatments with beta-propiolactone, binary ethylenimine, and the like.

[0038] As shown in the examples described below, when inactivated whole particles from four influenza viruses are administered intradermally in an amount of 15 μg or more as hemagglutinin (HA) per strain, the capacity to induce virus-specific antibodies in the nasal cavity is significantly enhanced, and a higher induction of antibodies can be achieved earlier as compared with intradermal and subcutaneous administrations of a split vaccine (FIG. 4A to 4D). Such a vaccine with good efficiency in inducing virus-specific antibodies in the nasal cavity has a high virus neutralizing activity and a high capacity to eliminate the virus in the nasal cavity (FIG. 5).

[0039] Therefore, intradermal administration of 15 μg HA or more per strain of inactivated whole influenza virus particles can be a vaccine therapy for seasonal influenza which induces virus-specific antibodies in the nasal mucosa. In other words, inactivated whole particles of influenza virus can be a seasonal influenza vaccine which induces virus-specific antibodies in the nasal mucosa and is administered intradermally at a dose of 15 μg HA or more per strain.

[0040] Here, “inducing virus-specific antibodies in the nasal mucosa means” means, for example, that the neutralizing antibody titer produced against the vaccinated influenza virus antigens in the nasal mucosa is 80 or more, preferably 160 or more. Here, the neutralizing antibody titer can be measured by assessing the inhibitory activity on the cytotoxicity of the virus against MDCK cells.

[0041] The seasonal influenza vaccine of the present invention can be formulated as a vaccine composition for intradermal administration (hereinafter referred to as the “vaccine composition of the present invention”).

[0042] In the present invention, “intradermal administration” refers to as administration into the dermis of the skin and does not mean that the administered vaccine composition is localized only in the dermis. Since the thickness of the dermal layer varies among individuals and even at different sites within an individual, the intradermally administered vaccine composition may be present only or primarily in the skin, or it may be present in the epidermis, which are included in the intradermal administration of the present invention.

[0043] The skin is composed of three layers: the epidermis, the dermis, and the subcutaneous tissue. The epidermis is the layer from 0.05 to 0.2 mm from the surface of the skin, the dermis is a layer from 1.5 to 3.0 mm located between the epidermis and the subcutaneous tissue, and the subcutaneous tissue is a layer from 3.0 to 10.0 mm located on the inner side of the dermis. For intradermal administration which is an administration into the dermis, a thinner and shorter needle than the needles for subcutaneous administration is used, and thus the pain and psychological burden at the needle pricking can be reduced compared with the existing vaccines administered subcutaneously or intramuscularly.

[0044] In addition to the inactivated whole influenza virus particles, the vaccine composition of the present invention may further contain a pharmaceutically acceptable carrier. Examples of the carrier include carriers commonly used in the production of vaccines, and specific examples thereof include a buffer, an emulsifier, a preservative (for example, thimerosal), an isotonic agent, a pH adjuster, an inactivating agent (for example, formalin), an adjuvant and an immunostimulant. An adjuvant is a substance which, when administered with an antigen, enhances the immune response to the antigen. However, the vaccine composition of the present invention does not necessarily require the addition of an adjuvant since the inactivated whole influenza virus particles themselves, which are the vaccine antigen, have a high capacity to induce antibodies as described above, and can be made into a composition without adjuvant.

[0045] The content of inactivated whole influenza virus particles in the vaccine composition of the present invention is 15 μg or more per virus strain in terms of hemagglutinin, that is, 15 μg HA or more per strain, preferably from 15 to 60 μg HA/strain, and more preferably from 15 to 21 μg HA/strain. Note that the hemagglutinin content is the value obtained by measuring with a test method defined by the WHO or national standards, such as the single radial immunodiffusion test method.

[0046] A dose per administration of the vaccine composition of the present invention should be, as antigen (inactivated whole influenza virus particles), 15 μg HA or more per strain of virus, and can be increased as appropriate in consideration of the age, sex, weight, and the like of the subject, but preferably from 15 to 60 μg HA/strain, more preferably from 15 to 21 μg HA/strain, and even more preferably 15 μg HA/strain, is administered once or more. Preferably, it is administered in multiple doses, in which case it is preferably administered at an interval from 1 to 4 weeks.

[0047] The volume per intradermal administration of the vaccine composition of the present invention is determined according to the site of administration and the administration device, but is usually from about 0.05 to 0.5 mL, preferably from 0.1 to 0.3 mL, and more preferably 0.2 mL

[0048] As an administration device for intradermal administration of the vaccine composition of the present invention, an intradermal needle or a microneedle capable of intradermal administration can be used, but for example, the protruding length of the needle tube of the intradermal needle or the microneedle is from 0.9 mm to 1.5 mm, preferably from 1.0 to 1.2 mm, and more preferably 1.2 mm.

[0049] The intradermal administration device may have one needle tube, or a plurality of needle tubes, but is preferably an intradermal needle having from one to three needle tubes, and more preferably three needle tubes.

[0050] The subject who receives the vaccine composition of the present invention includes humans and mammals other than humans, but humans are preferable. Examples of the mammals other than humans include rats, guinea pigs, rabbits, pigs, cows, horses, goats, sheep, dogs, cats, rhesus monkeys, cynomolgus monkeys, orangutans, and chimpanzees.

EXAMPLES

[0051] Hereinafter, the present invention will be described more specifically with examples, but the present invention is not in any way limited thereto.

[0052] Reference Example 1: Induction of virus-specific IgG in the nasal cavity by inactivated whole particle vaccine

[0053] A stock solution of the B/Yamagata lineage (B/Phuket/3073/2013 strain) from the influenza HA vaccine “SEIKEN” was used as a split antigen, and adjusted with 6.7 mM phosphate buffered saline containing 1 w/w% sucrose (pH 7.2) to have a hemagglutinin amount of 15 μg HA per 0.2 mL, and the adjusted solution was used as a split vaccine. In addition, inactivated whole particle antigen of the B/Yamagata lineage (B/Phuket/3073/2013 strain) prepared as described below was also adjusted in the same manner with 6.7 mM phosphate buffered saline containing 1 w/w% sucrose (pH 7.2) to have a hemagglutinin amount of 15 μg HA per 0.2 mL, and the adjusted solution was used as an inactivated whole particle vaccine.

[0054] The preparation of the inactivated whole particle antigen used in the present reference example is as described below. A virus of the B/Phuket/3073/2013 strain was inoculated into the chorioallantoic cavity of 12-day-old embryonated chicken eggs, and the chorioallantoic fluid was collected after 3 days of incubation. The collected chorioallantoic fluid was clarified by filter filtration, then adsorbed on barium sulfate salt, and eluted with a 12% sodium citrate solution to recover the influenza virus. The recovered virus was further purified by replacing the solution with 6.7 mM phosphate buffered saline (pH 7.2) by ultrafiltration, and after the buffer replacement, recovering the fraction containing the influenza virus by sucrose density gradient centrifugation. To this purified influenza virus, beta-propiolactone as an inactivating agent was added to obtain a final concentration of 0.05%, followed by allowing the mixture to react at 4° C. for 24 hours to inactivate the infectivity of the influenza virus. After this inactivation reaction, the buffer was replaced with 6.7 mM phosphate buffered saline containing 1 w/w% sucrose (pH 7.2) by ultrafiltration (MWCO: 100,000), and the resultant was used as an inactivated whole particle vaccine.

[0055] The administration solution prepared as described above (Table 1) was administered subcutaneously to BALB/c mice (female, 5 weeks old) at a dose of 0.2 mL per mouse, and whole blood was collected 21, 42, and 63 days after administration (collected from 8 mice per time point). In the same manner, each administration solution was administered twice at a 21-day interval, and whole blood was collected 42 and 62 days after the first dose (21 and 42 days after the second dose, respectively).

[0056] After collecting the whole blood, a pipetman was inserted from the pharyngeal side of the maxilla, to pour D-PBS containing 0.175% BSA and protease inhibitors (Thermo Fisher Scientific), and the solution recovered from the external nostrils was used as the nasal lavage fluid. The collected blood was centrifuged to prepare serum, and the serum HI antibody titer against the B/Phuket/3073/2013 strain was measured. For the nasal lavage fluid, the titer of IgG binding to the B/Phuket/3073/2013 strain was measured.

TABLE-US-00001 TABLE 1 Sampling Antigen Frequency of Day* Route of Morphology Vaccine Strain Administration (Days) Administration N Inactivated B/Phuket/3073/2013 1 21 Subcutaneous 8 Whole 42 Subcutaneous 8 Particle 63 Subcutaneous 8 Vaccine 2 42 Subcutaneous 8 (W.V.) 63 Subcutaneous 8 Split B/Phuket/3073/2013 1 21 Subcutaneous 8 Vaccine 42 Subcutaneous 8 (S.V.) 63 Subcutaneous 8 2 42 Subcutaneous 8 63 Subcutaneous 8 *Counted from the date of the first dose

[0057] The serum HI antibody titers against the B/Phuket/3073/2013 strain are as shown in FIG. 1. In comparison among the single-dose groups, the antibody titers in the split vaccine administration group were lower on Day 21 due to a slower induction of antibodies in the split vaccine compared with the inactivated whole particle vaccine, but the antibody titers in the split vaccine administration group gradually increased on Days 42 and 63, and after Day 42, the antibody titers in both vaccine administration groups were similar. In the double-dose groups, the inactivated whole particle vaccine had similar antibody titers on Days 42 and 63, but a tendency to slightly decrease was found for the split vaccine from Days 42 to 63. Therefore, on Day 42, the HI antibody titers for the inactivated whole particle vaccine and the split vaccine were equivalent, but on Day 63, they tended to be higher for the inactivated whole particle vaccine.

[0058] The virus-specific IgG titers of the nasal lavage fluids are shown in FIG. 2. In comparison among the single-dose groups, the IgG titers gradually increased from Day 21 to 63 in the split vaccine administration group, whereas the antibody titers were relatively low. By contrast, the inactivated whole particle vaccine administration group produced a bell shape with a peak at Day 42, showing a different trend from the HI antibody titers. Therefore, while the serum HI antibody titers on Day 42 and Day 63 were similar for both vaccines, the virus-specific IgG titers of the nasal lavage fluids showed a significantly higher induction of antibodies in the inactivated whole particle vaccine administration group than in the split vaccine administration group on Day 42.

[0059] In the double-dose groups, while the virus-specific IgG titers in the nasal lavage fluids on Day 42 also increased in the split vaccine administration group, the antibody titers were lower compared with the inactivated whole particle vaccine administration group. Furthermore, when compared on Day 63 (42 days after the second dose), the antibody titers tended to increase in the inactivated whole particle vaccine administration group, while those in the split vaccine group tended to decrease, which suggests that the inactivated whole particle vaccine was superior in terms of the durability of the virus-specific IgG in the nasal mucosa.

[0060] Reference Example 2: Virus Challenge Test

[0061] In the same manner as in Reference Example 1, the split antigen or inactivated whole particle antigen of the B/Victoria lineage (B/Texas/2/2013 strain) was adjusted with 6.7 mM phosphate buffered saline containing 1 w/w% sucrose (pH 7.2) to have a hemagglutinin amount of 15 μg HA per 0.2 mL, and the resultant was used as a split vaccine or inactivated whole particle vaccine.

[0062] The administration solutions prepared as described above (Table 2) were administered subcutaneously to BALB/c mice (female, 5 weeks old) at a dose of 0.2 mL per mouse once or twice at a 3-week interval. To the control group, saline (Otsuka Pharmaceutical Factory) was administered subcutaneously twice at a 3-week interval. Forty-two days after the first dose, the B/Brisbane/60/2008 strain of the B/Victoria lineage was inoculated into the nasal cavity under isoflurane anesthesia at 1×10.sup.4 TCID.sub.50/10 μL/head. Three days after virus inoculation, each mouse was euthanized by exsanguination, and then the nasal lavage fluids were collected in the same manner as in Reference Example 1.

[0063] The amount of virus contained in the collected nasal lavage fluids was measured by qPCR to compare and evaluate the capacity to eliminate the virus in the nasal mucosa.

TABLE-US-00002 TABLE 2 Dose Antigen Frequency of Administered Volume Sampling Morphology Vaccine Strain Administration (μgHA/head) Administered Date N Inactivated Whole B/Texas/2/2013 1 15 0.2 mL Day 45 8 Particle Vaccine (W.V.) Inactivated Whole B/Texas/2/2013 2 15 0.2 mL Day 45 8 Particle Vaccine (W.V.) Split Vaccine (S.V.) B/Texas/2/2013 1 15 0.2 mL Day 45 8 Split Vaccine (S.V.) B/Texas/2/2013 2 15 0.2 mL Day 45 8 Saline — 2 — 0.2 mL Day 45 8

[0064] The virus content of the nasal lavage fluids three days after virus inoculation is as shown in FIG. 3. By subcutaneous administration of the inactivated whole particle vaccine, the virus-specific IgG in the nasal mucosa increased 42 days after the single dose and after two doses (Reference Example 1), and in the virus challenge test, almost no virus was detected when inoculated at the above time points. On the other hand, with the subcutaneous administration of the split vaccine, it was confirmed that 42 days after the single dose, the virus content was slightly reduced compared with the control group, but the virus content of the nasal lavage fluid was high, probably due to low virus-specific IgG titers in the nasal mucosa. However, with the subcutaneous administration of the split vaccine, the virus-specific IgG titers in the nasal mucosa on Day 42 also increased by administering two doses (Reference Example 1), and therefore the virus contents in the double-dose groups were less than one-tenth compared with the control, which confirms a significant decrease in virus content in the nasal mucosa.

[0065] These results suggest that the induction of high levels of virus-specific IgG titers in the nasal mucosa is associated with the efficacy of the influenza vaccine.

[0066] Example 1: Evaluation of antibody induction in the nasal mucosa by intradermal administration of influenza vaccine

[0067] Inactivated whole particle vaccines and split vaccines were prepared using split antigens and inactivated whole particle antigens of four strains (A/H1N1, A/H3N2, B/Yamagata lineage, and B/Victoria lineage) prepared in the same manner as in Reference Example 1. The vaccines for intradermal administration were adjusted to have a hemagglutinin amount of 15, 3, or 0.6 μg HA per 0.2 mL, and the vaccines for subcutaneous administration were adjusted to have a hemagglutinin amount of 15, 3, or 0.6 μg HA per 0.5 mL, with 6.7 mM phosphate buffered saline containing 1 w/w% sucrose (pH 7.2).

[0068] The administration solutions prepared as described above (Table 3-1 and Table 3-2) were administered to the dorsal part of SD rats (male, 9 weeks old) twice at a 3-week interval, at 0.2 mL per mouse for intradermal administration and at 0.5 mL per mouse for subcutaneous administration. Twenty-one days after the second dose, blood removal was performed under isoflurane anesthesia, and then the nasal lavage fluids were collected. As in Reference Example 1, the method for collecting the nasal lavage fluid was to insert a pipetman from the pharyngeal side of the maxilla, to pour D-PBS containing 0.175% BSA and protease inhibitors (Thermo Fisher Scientific), and the solution recovered from the external nostrils was used as the nasal lavage fluid. Note that for intradermal administration, a Paskin triple-tip needle (Nanbu Plastics, 34G, 1.2mm) was used.

[0069] The recovered nasal lavage fluids were used to measure the titers of virus-specific IgG bound to each vaccine strain and to measure the neutralizing antibody titers against the A/Singapore/GP1908/2015 strain.

TABLE-US-00003 TABLE 3-1 Volume Antigen Dose Administered Administered Route of Morphology Vaccine Strain (μgHA/strain/head) (mL) Administration N Inactivated A/Singapore/GP1908/2015 15 0.2 Intradermal 8 Whole A/Singapore/INFIMH-16- Particle 0019/2016 Vaccine B/Phuket/3073/2013 (W.V.) B/Maryland/15/2016 Inactivated A/Singapore/GP1908/2015 3 0.2 Intradermal 8 Whole A/Singapore/INFIMH-16- Particle 0019/2016 Vaccine B/Phuket/3073/2013 (W.V.) B/Maryland/15/2016 Inactivated A/Singapore/GP1908/2015 0.6 0.2 Intradermal 8 Whole A/Singapore/INFIMH-16- Particle 0019/2016 Vaccine B/Phuket/3073/2013 (W.V.) B/Maryland/15/2016 Inactivated A/Singapore/GP1908/2015 15 0.5 Subcutaneous 8 Whole A/Singapore/INFIMH-16- Particle 0019/2016 Vaccine B/Phuket/3073/2013 (W.V.) B/Maryland/15/2016 Inactivated A/Singapore/GP1908/2015 3 0.5 Subcutaneous 8 Whole A/Singapore/INFIMH-16- Particle 0019/2016 Vaccine B/Phuket/3073/2013 (W.V.) B/Maryland/15/2016 Inactivated A/Singapore/GP1908/2015 0.6 0.5 Subcutaneous 8 Whole A/Singapore/INFIMH-16- Particle 0019/2016 Vaccine B/Phuket/3073/2013 (W.V.) B/Maryland/15/2016

TABLE-US-00004 TABLE 3-2 Volume Antigen Dose Administered Administered Route of Morphology Vaccine Strain (μgHA/strain/head) (mL) Administration N Split A/Singapore/GP1908/2015 15 0.2 Intradermal 8 Vaccine A/Singapore/INFIMH-16- (S.V.) 0019/2016 B/Phuket/3073/2013 B/Maryland/15/2016 Split A/Singapore/GP1908/2015 3 0.2 Intradermal 8 Vaccine A/Singapore/INFIMH-16- (S.V.) 0019/2016 B/Phuket/3073/2013 B/Maryland/15/2016 Split A/Singapore/GP1908/2015 0.6 0.2 Intradermal 8 Vaccine A/Singapore/INFIMH-16- (S.V.) 0019/2016 B/Phuket/3073/2013 B/Maryland/15/2016 Split A/Singapore/GP1908/2015 15 0.5 Subcutaneous 8 Vaccine A/Singapore/INFIMH-16- (S.V.) 0019/2016 B/Phuket/3073/2013 B/Maryland/15/2016 Split A/Singapore/GP1908/2015 3 0.5 Subcutaneous 8 Vaccine A/Singapore/INFIMH-16- (S.V.) 0019/2016 B/Phuket/3073/2013 B/Maryland/15/2016 Split A/Singapore/GP1908/2015 0.6 0.5 Subcutaneous 8 Vaccine A/Singapore/INFIMH-16- (S.V.) 0019/2016 B/Phuket/3073/2013 B/Maryland/15/2016

[0070] The results for the virus-specific IgG titers of the nasal lavage fluids are as shown in FIGS. 4A to 4D. The IgG titers against the A/Singapore/GP1908/2015 strain (A/H1N1 subtype) and the A/Singapore/INFIMH-16-0019/2016 strain (A/H3N2 subtype) confirmed the induction at high doses in the group of intradermal administration of inactivated whole particle vaccine or the group of subcutaneous administration of inactivated whole particle vaccine, with almost no induction in the other groups (FIGS. 4A and 4B). Among the groups in which the induction of virus-specific IgG was confirmed in the nasal mucosa, the highest induction efficiency was observed in the group which intradermally received 15 μg HA/strain/head of the inactivated whole particle vaccine. Therefore, the administration of an inactivated whole particle vaccine is effective for inducing virus-specific IgG against type A viruses in the nasal mucosa, and in particular, high antibody induction can be achieved by administering intradermally an inactivated whole particle vaccine at a high dose.

[0071] For the IgG titers against the B/Phuket/3073/2013 strain and the B/Maryland/15/2016 strain, the highest induction was shown in the group of intradermal administration of the inactivated whole particle vaccine (FIGS. 4C and 4D). For type B, induction of virus-specific IgG was observed also in the nasal mucosa in the group of intradermal administration of the split vaccine, but the induction efficiency was found to be the lowest in the group of subcutaneous administration (SV (S.C.)) of the split vaccine, which is identical to the current influenza vaccine. Therefore, intradermal administration of an inactivated whole particle vaccine was considered to be the one efficiently capable of inducing specific IgG against viruses of both type A and B in the nasal mucosa.

[0072] FIG. 5 shows the results of the neutralizing antibody titers against the A/Singapore/GP1908/2015 strain (A/H1N1 subtype) in the nasal lavage fluids. However, high virus neutralizing activity was shown only in the group which intradermally received 15 μg HA/strain/head of inactivated whole particle vaccine.

[0073] Therefore, also in the results for the virus-specific IgG titers in the nasal mucosa, the intradermal administration of the inactivated whole particle vaccine (15 μg HA/strain/head) had a high IgG titer against any strain and also had the highest virus neutralizing activity. That is, intradermal administration of a high dose of an inactivated whole particle vaccine increases the induction of antibodies which eliminate the virus in the nasal mucosa, which makes it a more effective influenza vaccine than the current vaccines.