Japanese researchers have submitted a new study showing that mRNA vaccines may actually enhance the infectivity of the Delta variant, making it completely resistant to the vaccine.
While the vaccines have shown to be effective against certain variants of concern (VOC), there is a “tradeoff “ that the same antibodies that offer vaccine-induced immunity make also fuel the growth of vaccine-resistant mutations, the researchers found. Specifically, these same antibodies can also “enhance the infectivity of SARS-CoV-2 by inducing the open form of the RBD (receptor binding domain).”
The researchers’ study examined the neutralizing and enhancing functions of these antibodies and found “an evolutionary pathway by which the Delta variant could achieve complete escape from vaccine-induced immunity, which provides important information for the design of next-generation vaccines.”
This information matters when making predictions for future mutations of the Delta variant, the researchers said, as “these results suggest that the Delta variant may acquire full resistance to BNT162b2 immune sera by acquiring additional mutations in the RBD that disrupt recognition of anti-RBD neutralizing antibodies.”
The case of an 86-year-old man who died after his first dose of the mRNA COVID-19 injection, but before he received the second, is posing questions about the safety, side effects, immunogenicity, and possibility of antibody-dependent enhancement (ADE) after receiving just one dose.
Writing in the International Journal of Infectious Diseases, study authors said the man died from acute renal and respiratory failure. Although he tested positive for the virus two days before he died, his autopsy attributed his death to acute bronchopneumonia and tubular failure. “These results might suggest that the first vaccination induces immunogenicity but not sterile immunity,” study authors said.
In a Twitter feed, however, at least one doctor questioned the circumstances under which the patient died, and suggested that the vaccine may set the stage for antibody-dependent enhancement (ADE). ADE occurs when antibodies help a virus infect cells, rather than prevent it.
“This is a very important cause, as it highlights the difference in the body’s immune response to sarscov2 after vax but before fully neutralizing titers,” AMM MD tweeted. “It also makes me wonder if this isn’t what is happening in breakthrough covid cases (develop covid months after complete vaccination, when immunity is waning). This could all serve as evidence for antibody-dependent enhancement.”