New Nature study confirms that mRNA vaccines are effective agai

  • Since the emergence of the Delta variant of the SARS-CoV-2 in many parts of the world, the number of so-called "breakthrough infections"—SARS-CoV-2 infection despite vaccination—has increased. Although the overall number is small, it raises questions about the efficacy of vaccine protection: Can the existing COVID-19 vaccines provide broad protection against the newly emerging mutant strains?


    The prestigious academic magazine Nature just published an important paper in the form of an Accelerated Article Preview that answers this topic.


    The Yale team verified that two current mRNA vaccines might improve the immune system's response to infection against more than a dozen variant strains of SARS-CoV-2, including the Delta variant, by evaluating blood samples from vaccine recipients. People who had been infected with SARS-CoV-2 prior to vaccination had greater immune responses to diverse variant strains, according to the findings.


    Professor Akiko Iwasaki, an immunologist at Yale University, co-led the study with epidemiologists Professor Nathan Grubaugh and Professor Saad Omer. The team collected hundreds of blood samples from 40 health care workers at Yale New Haven Hospital, including before the vaccination, during the two doses of the mRNA vaccine, and for a period of time after the vaccination.


    The researchers then tested the blood samples using live viruses from 16 newly discovered mutant strains that had been isolated. The researchers measured and compared antibody neutralization and T-cell immune response to each mutant strain because different mutant strains accumulate different mutations, some enhancing transmission and others producing immune escape.


    Despite the fact that the degree of the immune reaction varied from person to person and from variant strain to variant strain, the researchers observed an improved immune response in all samples obtained from volunteers following vaccination. At 7 days following the second dose of vaccine, neutralizing antibody titers against the SARS-CoV-2 spike-in protein and its receptor binding domain (RBD) peaked.


    The researchers also looked at immune escape from various variant viruses, finding that variants with E484K and N501Y/T mutations in the stinger protein caused the most significant reduction in neutralization capacity, implying that mutations at these key loci are important for vaccine protection attenuation. The Beta variant (B.1.351), discovered in South Africa, and the Gamma variant (P.1), discovered in Brazil, are two examples of mutant SARS-CoV-2.


    According to Professor Akiko Iwasaki's findings, the more common Delta variety did not cause the breakthrough infection due to the vaccine's failure to generate an immunological response, but rather due to the Delta strain's highly infectious characteristics, which broke through the immune system's resistance.


    "Because the Delta variant is more infectious than previous variants, its high transmission capacity better explains infections that arise after vaccination than its immune escape capacity," Professor Nathan Grubaugh noted.


    The researchers compared participants who had been infected before to vaccination to those who had not. They discovered that people who had been infected had a stronger immune response and higher antibody titers after immunization than people who had not been affected.


    Professor Iwasaki added, "Recovering from the initial experience of infection is equivalent to receiving the first vaccine shot." This also suggests, on the other hand, that for vaccination, booster targeting has an important role to play in boosting antibody and T-cell immune responses and is a relevant strategy for the future when mitigating the effects of new variants on antibody neutralization activity.