COVID-19 vaccines effectively prevent severe disease; haven’t shown signs of antibody-dependent enhancement as claimed by Robert Malone

COVID-19 vaccines will make SARS-CoV-2 more dangerous due to a mechanism called antibody-dependent enhancement (ADE)
Inadequate support: COVID-19 vaccines haven’t shown signs of antibody-dependent enhancement (ADE) in animal studies or vaccinated people. On the contrary, evidence indicates that vaccination reduces the risk of infection and the severity of the disease.
Misrepresents source: Fully vaccinated people who become infected tend to carry a lower viral load compared to unvaccinated people. The video misinterpreted an article by NBC News reporting on new data that is specifically about the Delta variant only. When infected with this variant, vaccinated people might have viral levels similar to unvaccinated people, but not higher as the video claimed.
Antibody-dependent enhancement (ADE) is a mechanism that occurs when antibodies don’t block infection by a virus, but instead increase its ability to infect cells, resulting in more severe disease. While ADE was a concern during COVID-19 vaccine development, previous knowledge allowed researchers to minimize this risk from early stages. COVID-19 vaccines haven't shown signs of causing more severe disease in animal studies, clinical trials, nor vaccination rollout. On the contrary, all FDA-authorized COVID-19 vaccines are highly effective in preventing severe disease.

FULL CLAIM: “The [COVID-19] vaccine causes the virus to become more infectious than would happen in the absence of vaccination”; “the [viral] titers in the vaccinated are actually higher than in the unvaccinated”


On 28 July 2021, the podcast War Room: Pandemic, hosted by Steve Bannon, published this video interview with molecular biologist Robert Malone, a former researcher at the Salk Institute. The video was widely shared on social media platforms, receiving more than 25,000 interactions on Facebook, Instagram, Reddit, and Twitter (see examples here, here, here, and here)

Both Bannon and Malone have previously spread misinformation on COVID-19 vaccines. In November 2020, Twitter permanently suspended Bannon after he suggested that certain U.S. officials like Anthony Fauci should be beheaded, violating the platform’s policies against the “glorification of violence”. YouTube later removed the podcast’s channel in January 2021 for violating the platform’s policies on misinformation.

During the interview, one of the primary claims made by Malone is that COVID-19 vaccination will make SARS-CoV-2 more dangerous due to a mechanism called antibody-dependent enhancement (ADE). ADE occurs when antibodies don’t block a virus from infecting cells, but instead improve its ability to infect cells. This phenomenon increases the risk that individuals with preexisting antibodies from previous natural infection or vaccination develop more severe disease when exposed again to the virus.

Claims that COVID-19 vaccines would cause ADE started circulating on social media platforms early in the pandemic. Such claims are baseless and actually contradict scientific evidence, as we explain below.

The first reports of ADE came from patients with dengue virus infections. Researchers observed that previous infection with one of the four serotypes of the virus often worsened the symptoms of the disease if the person had a second infection with a different serotype. This phenomenon caused problems in the development of vaccines for dengue, respiratory syncytial virus (RSV), measles, and some coronaviruses, including severe acute respiratory syndrome (SARS)-associated coronavirus (SARS-CoV-1) and Middle East Respiratory Syndrome Coronavirus (MERS-CoV).

Scientists did express concern over the potential of ADE during the development of COVID-19 vaccine candidates[1]. However, previous knowledge helped researchers to minimize this risk from the early stages of COVID-19 vaccine development[2]. This influenced critical decisions during vaccine design, such as the choice to target the spike protein instead of other viral proteins that had caused ADE in vaccine candidates against past coronaviruses[3]. Researchers also conducted specific animal studies to detect ADE and closely monitored clinical trial participants for any sign of this phenomenon during the testing of COVID-19 vaccine candidates[4].

The result of this awareness is that the COVID-19 vaccines developed so far showed no signs of ADE in animal studies, clinical trials, or during vaccine rollout. Real-world studies further demonstrate that all FDA-authorized COVID-19 vaccines are highly effective in preventing severe disease and death[5,6]. Furthermore, infections in fully vaccinated individuals are rare and tend to produce milder symptoms than in those who didn’t receive the vaccine[6,7]. This is exactly the opposite of what one would expect if ADE was occurring.

During the interview, Malone further claimed that SARS-CoV-2 variants are “most likely developing in the people who have been vaccinated”, increasing the risk of ADE. As Health Feedback explained in previous reviews, current evidence doesn’t support the claim that COVID-19 vaccines lead to more viral variants, and actually contradicts it.

Each time the virus replicates, it can introduce mutations, which are changes in its genetic sequence. These changes are random and a natural process in viral evolution. The more infections the virus causes, the more times it replicates, increasing the likelihood of generating new mutations that might spread as new variants. Some studies suggest that long-lasting infections also favor the development of new mutations.

Because COVID-19 vaccines effectively prevent infections, hospitalizations, and deaths, they also make it less likely for the virus to mutate and for new variants to spread. In contrast, unvaccinated individuals are more likely to get infected and develop severe COVID-19, increasing the chances of new variants to emerge. If COVID-19 vaccines did lead to more variants, those regions with higher vaccination rates would observe more new variants circulating among the population. This isn’t the case. In fact, all current variants of concern emerged in 2020, before the vaccination campaigns began.

Given the above evidence that COVID-19 vaccines aren’t worsening the disease, on what grounds claimed Malone that COVID-19 vaccines cause ADE?

During the interview, Malone mentioned a 27 July 2021 article by NBC News discussing an imminent update on face mask guidance from the U.S. Centers for Disease Control and Prevention (CDC). This update reversed previous indoor mask-wearing policy and recommended that fully vaccinated people wear masks indoors again in places with high transmission rates.

According to Malone, NBC News reported that this change in guidance responded to new data suggesting that people vaccinated against COVID-19 had more virus than unvaccinated individuals. Malone also shared this claim in a tweet, together with a screenshot from a USA Today article echoing that of NBC News. USA Today removed this part of the article in a later update. However, neither NBC News nor USA Today stated what Malone claimed they did. Instead, what they reported:

“The Biden administration is issuing new guidance Tuesday recommending indoor mask use in areas with high transmission rates, after reviewing new data suggesting fully vaccinated individuals are not just contracting Covid-19, but could also be carrying higher levels of virus than previously understood and potentially able to infect others, according to multiple sources close to the discussion.”NBC News.

“NBC News, citing unnamed officials aware of the decision, reported it comes after new data suggests vaccinated individuals could have higher levels of virus and infect others amid the surge of cases driven by the delta variant of the coronavirus.”USA Today.

Multiple studies show that the few people who develop COVID-19 after receiving the Pfizer-BioNTech COVID-19 vaccine tend to have a lower viral load than unvaccinated people[8,9]. New data suggest that viral levels in vaccinated individuals who get infected with the Delta variant might be as high as in unvaccinated individuals, but not higher as Malone claimed[10]. These data imply that some vaccinated individuals who get infected might still transmit the virus to others. This is what informed the CDC’s decision to reverse face mask policy, as the NBC News article reported.

In summary, Malone misrepresented the NBC News article to claim that vaccinated individuals have higher virus levels than unvaccinated individuals, which is inaccurate. Vaccinated people who become infected generally tend to have a lower viral load compared to unvaccinated people. However, when infected with the Delta variant in particular, viral loads in vaccinated individuals can be similar to those in unvaccinated people, but not higher.

COVID-19 vaccines are highly effective in preventing severe COVID-19 and reducing the risk of infection. Malone’s claim that the COVID-19 vaccines cause ADE is contradicted by the fact that vaccinated individuals who become infected tend to have milder symptoms than unvaccinated individuals, rather than the opposite. By reducing the risk of infection and severe disease, COVID-19 vaccines also limit the spread of the virus within the population, making it less likely for new variants to emerge.


The medicinal chemist Derek Lowe conducted a a detailed analysis of ADE in the context of COVID-19 vaccines in his blog on Science Translational Medicine. He also discussed previous research on ADE in different diseases and the mechanisms that can lead to the phenomenon.



Published on: 31 Jul 2021 | Editor:

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