Dr. Paul Offit explains why COVID-19 vaccines are unlikely to cause a worsening of disease, called antibody-dependent enhancement.
Do COVID-19 vaccines cause antibody-dependent enhancement (ADE)?
Paul Offit, MD: Hi, my name is Paul Offit from the Vaccine Education Center. One issue that's come up regarding the safety of coronavirus vaccines is: Could they cause something called antibody-dependent enhancement? Now, this is something that's been seen with a virus called dengue virus, which is actually a very common virus in this world, although not common really in the continental United States. There are four different types of dengue virus. When you're infected with one type of dengue virus and you recover, and then you're infected with a second type of dengue virus, sometimes what happens is people, because they've developed an antibody response to that first and really different type of dengue virus, when they're then exposed to a second type of dengue virus, actually have much worse disease than if they'd never been infected with any type of dengue before.
So people are worried that maybe with this virus, this SARS-CoV-2 virus, that that could also be true here, because there was a suspicion from some of the animal model studies that were done with SARS-CoV-1 virus, which was a virus that sort of came up in 2002 but then in a couple of years was gone, that that also might be true here. But there are a number of reasons why it's unlikely to happen, very unlikely to happen.
First of all is if you're infected with human coronavirus, and there are four different types of human coronavirus, and then you're infected with a second different type of human coronavirus, you don't have that phenomenon of so-called antibody-dependent enhancement, where you have a much worse second infection than first infection.
Secondly, when you look at people, and these were studies done in the early 1990s, that were experimentally challenged with human coronavirus and then challenged again with human coronavirus, sort of under sort of the experimental conditions, also, you never saw antibody-dependent enhancement.
Third, if you look at animals who are infected with SARS-CoV-2 virus, experimental animals, and then experimentally infected again with SARS-CoV-2 virus, there's not antibody-dependent enhancement. And similarly, if you look at animals that are given a SARS-CoV-2 vaccine and then challenged with the natural virus, the SARS-CoV-2 virus, they too don't develop antibody-dependent enhancement.
And then lastly, and finally, with people who are infected with SARS-CoV-2, when they are given antibodies, so-called convalescent plasma directed against SARS-CoV-2, they too don't develop antibody-dependent enhancement.
So, I think the concerns that were raised by what happened with SARS-1 are understandable, but we now have five separate pieces of evidence that suggest that that is not going to be a problem with this virus or with this vaccine associated with this virus.
Related Centers and Programs: Vaccine Education Center
Last Reviewed on Feb 10, 2021