How long after the second dose are you immune?

Of course, we’re referring to the second dose of the COVID-19 vaccine

The COVID-19 vaccine is becoming available to more and more people. (Pexels stock image)

More and more people are now able to receive the COVID-19 vaccine, and President Joe Biden has said he’s aiming to make every adult in the U.S. eligible for vaccination no later than May 1.

It’s been a long past year or so, but it seems we now have light at the end of this pandemic tunnel.

A related question seems to keep popping up: How long after receiving the second COVID dose are you immune, or fully protected, against the virus?

Ohio State University published a blog addressing that question and several other FAQs, so we thought we’d address it here.

The short answer? Two weeks.

As in ...

How long does it take for the COVID-19 vaccine to work?

“Regardless of which vaccine you get, you won’t reach full protection until two weeks after your second or final dose. That’s about how long it takes your immune system to mount an antibody response to the vaccine.”

Remember, three vaccines are currently being distributed: Moderna, Pfizer and Johnson & Johnson. The first two require two doses -- and Johnson & Johnson is the only one that’s just a single dose.

Here’s more from Ohio State: “All vaccines work this way. Think of it in terms of when you have a cold—it takes your body a good amount of time to rid itself of what’s making you sick. A vaccine is essentially faking out your immune system and triggering a similar response. After the shot, your body has some work to do.”


Am I protected from COVID-19 after the first shot?

“The first of a two-dose COVID-19 vaccine does offer some protection, but not nearly as much as you’ll get from both doses.

For example, the Pfizer two-dose vaccine has 95% effectiveness at preventing symptomatic COVID-19 infection—but studies show that the first dose is only about 52% effective. This is why the second dose is so important, and why we’re so diligent about scheduling you for your follow-up shot.”

Don’t skip that second dose. You have 21 days for Pfizer and 28 for Moderna.

And now you know.