怎么设计一个类内函数，去识别字符并且计数？

题目：声明一个 student 类,私有成员为疫苗的次数,每次疫苗的类型。声明静态成员,记录没打疫苗的和分别打一针、二针、三针的人数,以及各类疫苗的总接种次数。
我的问题：怎么识别我输入的疫苗类型，然后在对应的次数上叠加啊？（完全没有头绪）

#include <iostream>
#include <vector>
using namespace std;
//疫苗种类
enum VACCINE_TYPE
{
    miehuo    = 4,//灭活疫苗
    yadanw     = 5,//亚单位疫苗
    xianbd     = 6,//腺病毒载体疫苗
};


class student
{
public:    
    static int people_novaccine;//没打疫苗的人数
    
    static int people_first;    //一针接种人数
    static int people_second;    //二针接种人数
    static int people_third;    //三针接种人数

    static int people_miehuo;    //灭活疫苗接种人数
    static int people_yadanw;    //亚单位疫苗接种人数
    static int people_xianbd;    //腺病毒载体疫苗
    static void show()
    {
        cout<<"没打疫苗的人数："<<people_novaccine<<endl;
        cout<<"一针接种人数："<<people_first<<endl;
        cout<<"二针接种人数："<<people_second<<endl;
        cout<<"三针接种人数："<<people_third<<endl;
        cout<<"灭活疫苗接种人数："<<people_miehuo<<endl;
        cout<<"亚单位疫苗接种人数："<<people_yadanw<<endl;
        cout<<"腺病毒载体疫苗："<<people_xianbd<<endl;
    }
public:
    student(){vaccine_time=0;}
    student(int vtime,vector<int> _v)
    {
        vaccine_time = vtime;
        
        v.resize(_v.size());
        for(size_t i=0;i<_v.size();i++)
            v[i]=_v[i];
            
        if(vtime == 0) student::people_novaccine++;
        else if(vtime == 1) student::people_first++;
        else if(vtime == 2) {student::people_first++;student::people_second++;}
        else if(vtime == 3) {student::people_first++;student::people_second++;student::people_third++;}
        
        for(size_t i=0;i<_v.size();i++)
        {
            if(v[i] == miehuo)student::people_miehuo++;
            if(v[i] == yadanw)student::people_yadanw++;
            if(v[i] == xianbd)student::people_xianbd++;
        }
    }
private:
    int vaccine_time;
    vector<int> v;
};
int student::people_novaccine = 0;//没打疫苗的人数
int student::people_first = 0;    //一针接种人数
int student::people_second = 0;    //二针接种人数
int student::people_third = 0;    //三针接种人数
int student::people_miehuo = 0;    //灭活疫苗接种人数
int student::people_yadanw = 0;    //亚单位疫苗接种人数
int student::people_xianbd = 0;    //腺病毒载体疫苗接种人数


int main() {
    vector<int> v1={};
    
    vector<int> v2;
    v2.resize(1);
    v2[0] = miehuo;
    
    vector<int> v3;
    v3.resize(2);
    v3[0] = miehuo;
    v3[1] = yadanw;
    
    vector<int> v4;
    v4.resize(3);
    v4[0] = miehuo;
    v4[1] = yadanw;
    v4[2] = xianbd;
    
    student s1(3,v4);
    student s2(2,v3);
    student s3(1,v2);
    student s4(0,v1);
    
    student::show();
    return 0;
}