The need to use "One" and "Two"

Hi, Tony,

@Tony C posted:

There are two types of vaccines: one is Pfizer, which is......, and the other (one) is Sinovac, which is.....

You should use use "one" and "the other" there. Please also note that the relative clauses are non-restrictive and should be preceded by a comma.

We use "one" and "two," or "first" and "second," when we enumerate items to organize our ideas, for example: There are several requirements that vaccines need to meet: first, ...; second, ...; third, ...

Thanks so much Gustavo. But when we enumerate item to organise our ideas can we make an independent sentence when using fist, second and third (instead of using semi colon ;, especially when it is a long sentence. See my example below and let me know what your thoughts on this.

I strongly believe that winter is better than summer. My first reason is there is no mosquito in winter. My second reason is in winter we can go to snowy mountain and play snow and make a snowman. My third reason is we can enjoy hot chocolate during winter as we feel warm and relaxing.

Yes, that's correct. Note, however, that semicolons can also be used to separate independent clauses, especially when they are not too long.