 We find the regions of large population or high effective regeneration number should be vaccinated with priority and that frequent travels tend to cause an influence to enhance the spread especially in the up-trend stage of infections and in regions of smaller populations.
<clarity>  We find the regions of large population or high effective regeneration number should be vaccinated with priority and that frequent travels tend to cause an influence to enhance the spread especially in the up-trend stage of infections and in regions of smaller populations.
 We find the regions of large population or large effective regeneration number should be vaccinated with priority and that frequent travels tend to cause an influence to enhance the spread especially in the up-trend stage of infections and in regions of smaller populations.