22 <latexit sha1_base64="oMr7G/svA9fDN76DQkTXeU9g4jE=">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</latexit> dS(t) dt = b(1 e) µS(t) S(t)I(t) dI(t) dt = (µ + )I(t) + S(t)I(t) dR(t) dt = be µR(t) I(t) ((1-e)N,0,eN)) = (b(1-e)/μ, 0, be/μ) を安定な平衡値としてもつ このとき少数の感染者が⼊ってきたら、再⽣産過程は以下 <latexit sha1_base64="InRFdEtl5ZpoewqBvfuaDU8L5JY=">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</latexit> dI(t) dt = (µ + )I(t) + b(1 e) µ I(t) > 0 <latexit sha1_base64="F7m6a5Ev4Axl7ctn8T9eiPzISqo=">AAACIHicbVDLSgMxFM3UV62vqks3wSK0qGVGiroRim5c1mIf0Cklk95pQ5OZIckIZeiPuPRLXKobceFCv8b0sdDWAxcO55xLco8Xcaa0bX9ZqaXlldW19HpmY3Nreye7u1dXYSwp1GjIQ9n0iALOAqhppjk0IwlEeBwa3uBm7DceQCoWBvd6GEFbkF7AfEaJNlInW6rmoYCvsNv1JaGJ64Em2MN55xQKo8QVcd7MseEmMxGrHRt3sjm7aE+AF4kzIzk0Q6WT/XS7IY0FBJpyolTLsSPdTojUjHIYZdxYQUTogPSgZWhABKh2MrluhI+M0sV+KM0EGk/U3xsJEUoNhXfiCRMWRPfVvD0W//NasfYv2wkLolhDQKdv+THHOsTjtnCXSaCaDw0hVDLzXUz7xDSlTacZ04Mzf/UiqZ8VnfNi6a6UK1/PGkmjA3SI8shBF6iMblEF1RBFj+gZvaI368l6sd6tj2k0Zc129tEfWN8/I+ifNw==</latexit> R(e) = b(1 e) µ(µ + e) = (1 e)R0 実効再⽣産数 <latexit sha1_base64="uMrhJGBeAXrqFujfAKJogCUqZoM=">AAACAHicbVDLSsNAFJ3UV62v+Ni5GSyCCy2JFHUjFN24rGIf0IYwmU7aoTOTMDMRasjGL3GpbsSt/+HCv3HaZqGtBy4czrmXe+8JYkaVdpxvq7CwuLS8Ulwtra1vbG7Z2ztNFSUSkwaOWCTbAVKEUUEammpG2rEkiAeMtILh9dhvPRCpaCTu9SgmHkd9QUOKkTaSb+8ReAndk24vlAinbpbe+U7m22Wn4kwA54mbkzLIUfftr24vwgknQmOGlOq4Tqy9FElNMSNZqZsoEiM8RH3SMVQgTpSXTq7P4KFRejCMpCmh4UT9PZEirtSIB8cBN80c6YGatcfif14n0eGFl1IRJ5oIPN0VJgzqCI7TgD0qCdZsZAjCkppzIR4gE4U2mZVMDu7s1/OkeVpxzyrV22q5dpUnUgT74AAcARecgxq4AXXQABg8gmfwCt6sJ+vFerc+pq0FK5/ZBX9gff4Ao3eVJw==</latexit> e = 1 1 R0 R(e)<1であればよいので、 臨界免疫化割合 これより⼤きいと集団免疫