Use result from first shader pass in second pass

I'm trying to write a shader for a SpriteRenderer which does a gaussian blur on the texture which is typically done in 2 passes. The first pass does a vertical blur and the second pass uses the result of this vertical blur and applies a horizontal blur.

I've gotten the vertical blur to work :

 Shader "Tutorial/Textured Colored" 
 { 
     Properties
     {
         _VBlurAmount ("Vertical Blur Amount", Float) = 0.00195
         _HBlurAmount ("Horizontal Blur Amount", Float) = 0.00195
         _Color ("Main Color", Color) = (1,1,1,0.5) 
         _MainTex ("Texture", 2D) = "white" { } 
         _AlphaTex ("Texture", 2D) = "white" { } 
     } 
         
     SubShader
     {
         Tags { "RenderType"="Transparent" "Queue"="Transparent" }
         LOD 200
         Blend SrcAlpha OneMinusSrcAlpha
         ZTest Less
  
         // Vertical blur pass
         Pass
         {
             Blend SrcAlpha OneMinusSrcAlpha
             Name "VerticalBlur"
                         
             CGPROGRAM
             #pragma vertex vert
             #pragma fragment frag            
             #include "UnityCG.cginc"
             
             sampler2D _MainTex;
             float     _VBlurAmount;
             
             struct v2f 
             {
                 float4  pos : SV_POSITION;
                 float2  uv  : TEXCOORD0;
             };
             
             float4 _MainTex_ST;
             
             v2f vert (appdata_base v)
             {
                 v2f o;
                 o.pos = mul(UNITY_MATRIX_MVP, v.vertex);
                 o.uv = TRANSFORM_TEX(v.texcoord, _MainTex);
                 return o;
             }
             
             half4 frag (v2f i) : COLOR
             {
                 half4 sum = tex2D(_MainTex, float2(i.uv.x, i.uv.y)) * 0.16;
                 sum += tex2D(_MainTex, float2(i.uv.x, i.uv.y - _VBlurAmount)) * 0.15;
                 sum += tex2D(_MainTex, float2(i.uv.x, i.uv.y + _VBlurAmount)) * 0.15;
                 sum += tex2D(_MainTex, float2(i.uv.x, i.uv.y - 2.0 * _VBlurAmount)) * 0.12;
                 sum += tex2D(_MainTex, float2(i.uv.x, i.uv.y + 2.0 * _VBlurAmount)) * 0.12;
                 sum += tex2D(_MainTex, float2(i.uv.x, i.uv.y - 3.0 * _VBlurAmount)) * 0.09;
                 sum += tex2D(_MainTex, float2(i.uv.x, i.uv.y + 3.0 * _VBlurAmount)) * 0.09;
                 sum += tex2D(_MainTex, float2(i.uv.x, i.uv.y - 4.0 * _VBlurAmount)) * 0.05;
                 sum += tex2D(_MainTex, float2(i.uv.x, i.uv.y + 4.0 * _VBlurAmount)) * 0.05;
                 sum += tex2D(_MainTex, float2(i.uv.x, i.uv.y - 5.0 * _VBlurAmount)) * 0.025;
                 sum += tex2D(_MainTex, float2(i.uv.x, i.uv.y + 5.0 * _VBlurAmount)) * 0.025;
                
                 return sum;
             }
             ENDCG
         }
  
         // Horizontal blur pass
         Pass
         {
             //how do I get result from previous pass?
         }
     }
     Fallback "VertexLit"
 } 

But I don't know how to get the result for the second, horizontal pass. Any help appreciated, not to forget that it needs to work on a SpriteRenderer. Also, any pointers on making this shader better are appreciated :)