BThis is because doctors are refuse a lot of infected person, they may afing to test a lot of people with corona virus symptoms, and these people, if infected, may then infect healthy people.

It is not quite clear what you are saying the doctors are refusing to do.

Also, I know some hospitals in Japan are refusing to admit patients with coronavirus symptoms.

Also "infect" is correct, not "affect."

Another possibility is to combine part of this sentence with the previous sentence:
Every day, the number of infected people has increased because doctors are refusing to test a lot of people for the virus. If these people are infected, they may infect healthy people.

Opinion: Do you think that Japan is handling this situation well compared to other countries?

Every day, the number of infected personople has increased.

You are talking about a number of people/a group of people not just one person

Because doctors refuse a lot of infected personople, theyse people may affect healthy people.

Same as above.

First(ly), I thoughtink Prime Minister Abe should indicateput out an emergency announcement early.

Second(ly), I thoughtink he should stop going in the place of crowdto crowded places.

Third(ly), people should work in their home withby using their PC or smartphone.

If we can do it smoothly, we don’t need to go into our office or school.

It will be important for us to work in ourat home.

Every day, infected person has increasedthere are more infected people.

あるいは：Every day, more people get infected.

Because doctors refuse a lot of infected person, theyople, those people may affect healthy people.

「They」をいうと、その「they」は医者あるいは感染者かはっきりではありません。

Firstly, I thoughtink Prime Minister Abe should indicatehave put out an emergency announcement earlyier.

Secondly, I thought hink we should stop going in the place of crowdto busy places.

Third,ly, I think people should work in theirat home with using their PCcomputers or smartphones.

If we can do it smoothly, we dwon’'t need to go to our offices or schools.

It will be important for us to work in ourfrom home.

"Work from home" はよく使う表現です。

Do you think Japan, or your school, should do something differently?

Every day, infected person has increasmore people are infected.

BThis is because doctors are refuse a lot of infected person, they may affect healthy peopleing to test those who are infected. Raising the risk to affect those who are healthy.

First, I thoughtink Prime Minister Abe should have indicated an emergency announcement earlyier.

Second, I thoughtink he should stop going in the place of crowdto crowded places.¶
Second, I think he should stop going to crowded areas.

Third, people should work be able to work from home using their home withPC or smartphone.¶
Lastly, people should be able to work from home using their PC or smartphone.¶
Finally, people should be able to work from home using their PC or smartphone.

If we can do it smoothly, we don’t needthen it would not be necessary to go our office or school.

Every day, the amount of infected personople has increased.

Because doctors refuseturn away a lot of infected personople, they may affect healthy people.

Firstly, I thoughtink Prime Minister Abe should indicatehave made an emergency announcement earlyier.

Secondly, I thoughtink he should stop going in the place of crowdto crowded places.

Thirdly, people should work in their home withat home using their PC or smartphone.

If we can do it smoothly, we dwon’'t need to go to our offices or schools.

It will be important for us to work in ourfrom home.

Every day, [The number of] infected personople has increased.

You are talking about a total "number" of people. You can have 1 person or >1 (many) people.

Because doctors refuse a lot of infected person, theyople, those, who are infected, may affect healthy people.

The doctors (plural) are refusing infected people (plural) - in this case.

I have three ideas.

using "thought" is correct in the next sentences if "have" is turned into has.
"has" is in the past tense.
thought works with it because it is also in the past tense.

First[ly], I thoughtink Prime Minister Abe should indicate emergency announcement early.

the ly on "Firstly" is grammatically correct, but native speakers don't always use it. You could add on "ly" to all any number introduction.
Firstly... Secondly... Thirdly...

Second, I thoughtink he should stop going in the place of crowdcrowded place.

Not enough information to correct this well, but this makes more sense.

Third, people should work in their home withby using their PC or smartphone.

... home, using their...
... home with their PC...
These are all correct.
"with" and "using" do the same idea/job twice.

It will be important for us to work in our home.

This is correct, but when you use will it makes sense to say more.
You should say more because will changes the sentence to the future.
"It will be important for us to work in our home in the future, if we want to do this smoothly."

or

"If we want to do this smoothly, it will be important for us to work in our home in the future."