Why Vaccinated People Are Getting ‘Breakthrough’ Infections

by Wendy Wisner
Scary Mommy, Fusion Medical Animation/Unsplash and MoMo Productions/Getty

I’ve started to think of May-July of this past year as the “honeymoon period” for COVID-19. After a terrible winter surge of cases and death, numbers were starting to plummet in most places in the U.S. Many essential workers and older people were fully vaccinated, and those of us regular folks who wanted vaccines could get them. We were finally starting to reunite with friends and family members. There were long-awaited hugs and many tears.

We all posted pics of our reunions with hashtags like #thankyouscience and #vaccinesbringuscloser. These vaccines were true miracles, and were finally helping us to see the light at the end of this disaster. I mean, those mRNA shots were like 95% effective, and the CDC was saying that vaccinated people, even on the off chance they become infected, weren’t likely to transmit the virus to others.

Those of us who were fully vaccinated felt like we had a coat of armor around us. Even without our younger kids eligible for the vaccine, we were basically operating under the assumption that we could hang out with other vaccinated people, and all would be right in the world.

Then we started to hear about Delta, the most transmissible variant of COVID out there—a variant that was possibly making the vaccines less effective. A variant that could pierce that wonderful vaccine armor us vaccinated folks were getting used to wearing. We started to hear about real-life cases of fully vaccinated folks getting infected with Delta. Yes, the cases were generally mild, but these were healthy, fully vaccinated people.

WTAF was going on?!

I know that I started to get really nervous when I read a twitter thread by John Pavlovitz where he described his whole entire family getting COVID, even after three out of four of them were fully vaccinated. His unvaccinated child got the virus first, and then it spread to the rest of his family. His fully vaccinated teen tested positive but remained asymptomatic. But he and his wife got sick.

Like the vast, vast majority of fully vaccinated people who get breakthrough cases of COVID, Pavlovitz and his wife got relatively mild cases and were able to recover at home. Doctors agree that even with Delta’s ability to escape the vaccines, the vaccines are still highly protective against severe disease and death, which is basically their main point.

“By no means does that mean that you’re dealing with an unsuccessful vaccine,” Dr. Fauci told the New York Times. “The success of the vaccine is based on the prevention of illness.” As the Times points out, over 97% of people hospitalized with COVID did not receive the vaccine.

The CDC is not tracking mild breakthrough infections, so it’s sort of impossible for us to understand what is happening currently in terms of these infections. It’s clear that more breakthrough infections are being reported in the news—and more of us are hearing about them anecdotally. But it’s still unclear what each vaccinated person’s chances are of getting a breakthrough infection.

Estimates of how the vaccines’ efficacy has diminished in light of Delta have varied from 88% to 64% to an alarming and depressing 39%.

Given all of this, many of us are asking, “Why on earth is this happening? Why the heck aren’t the vaccines doing more to ensure that I don’t pick up this damn virus?”

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As science writer Apoorva Mandavilli outlines in The New York Times, breakthrough infections happen for a number of reasons, and the Delta variant is making them more likely mostly because it’s just so much more infectious. Delta is two times as transmissible as original strains of COVID, and people who are infected have 1000 times more virus in their body.

That means that when a vaccinated person is exposed to Delta, their body has a much bigger job ahead to fight off the virus. Their immune system is primed to do so because of the vaccine—it’s just a tougher job, and the virus is more able to take hold.

As Mandavilli explains, “A vaccinated person exposed to a low dose of the coronavirus may never become infected, or not noticeably so. A vaccinated person exposed to extremely high viral loads of the Delta variant is more likely to find his or her immune defenses overwhelmed.”

When that happens, infection might take place. But because your immune system knows what’s up when it comes to COVID, you are much more likely to clear the bug out of your system faster, and with fewer awful symptoms.

In light of all that’s going on, many public health experts are urging even fully vaccinated folks to go back to taking precautions, including masking up indoors again. Vaccines still are amazing and miraculous but with so much highly transmissible virus circulating, taking a “layered” approach to protection is starting to make the most sense, as Andy Slavitt explains.

I personally never stopped masking indoors, because I have a child at home who is too young to be vaccinated, and I want to do everything in my power to ensure that I don’t accidentally bring an infection home to him. Now that the chances of me getting a breakthrough infection have increased, I’m being more diligent than ever.

And of course, as Dr. Leana Wen points out, part of the problem is that so much of our country is still not vaccinated. So when you have both a much more highly contagious variant, and many unvaccinated people getting infected with it, you are just going to have more virus circulating, increasing the likelihood that vaccinated people will catch it.

This underlines the point, yet again, that this pandemic is a group project. It’s not just about individual protection: the vaccines hold up best if large swaths of the population are vaccinated. Delta is proving that we are just not there yet.


So can y’all unvaccinated folks hurry up and get vaccinated so those of who did the right thing don’t have to continue shouldering the burden of all this? Pretty please? Asking on behalf of America.