There is probably some level of immunity after one dose, but we don't know how complete the protection is and how long it lasts.

Make sure you get the second dose of the same vaccine as the first (so if you got the Pfizer vaccine the first time, get the Pfizer the second time, too).

The second dose of the Pfizer vaccine is typically given after three weeks and the Moderna after four weeks.

After the second dose, it probably takes another two or three weeks to develop the optimal degree of immune protection.

Let's say you've received one dose of vaccine.

And if you did get it, according to what we know from clinical trials, you're probably going to have less severe disease than if you didn't get the vaccine.

CNN: Once an older adult has received the second dose, and it's been three weeks, can they visit their grandchildren?

Wen: Maybe.

We know that elderly individuals and those with chronic medical conditions have a much elevated risk of severe illness and death, and the vaccine will substantially reduce these outcomes.

Because you do have much reduced risk as a result of getting the vaccine, it's a personal judgment as to what activities you most value and may want to consider bringing back.

Getting the vaccine reduces your overall risk, but that doesn't mean you should now do every high-risk activity.

Can I see them without my mask, indoors?

Wen: It's probably pretty safe to see others who were also vaccinated, after everyone gets both doses and waits a few weeks.

In a way, you could see getting the vaccine like being in quarantine.

If both parties have been in quarantine, it's probably pretty low risk to safely see one another.

In the same way, if both parties have received the vaccine, you can probably see one another relatively safely.

But because we don't know if vaccinated people could still be asymptomatic carriers, if you participate in risky behaviors, you could infect others you have close contact with who aren't vaccinated.

That includes seeing other people who are vaccinated, but not wearing a mask — based on what we know now, they could have the virus and pass it onto you, and you could pass it onto the people you live with.

Also, clinical trials are just getting started on children, so it will take probably until summer or fall for children to be vaccinated.