Dr Landau’s team would likely have seen a similar increase in the potency of the vaccine if they had looked at the data over time, said Dr Dan Barouch, a virologist at Beth Israel Deaconess Medical Center in Boston. Data on the J. & J. The strength of the Delta variant vaccine on day 29 is not significantly different from those reported in his own study, Dr Barouch said.
“Basically I don’t see that there is a mismatch,” he said. “The question is that of the kinetics, it is not only the magnitude, because the immune responses are not static over time. The new study also did not take into account other components of the immune defense, he added.
Dr Landau and his colleagues examined blood samples taken from 17 people who had been immunized with two doses of an mRNA vaccine and 10 people with one dose of J. & J. vaccine.
The J. & J. The vaccine started out with lower efficacy than mRNA vaccines and showed greater decline in efficacy against Delta and Lambda variants. “The lower baseline means what’s left to counter Delta is very weak,” said Dr. Moore. “It’s a big concern. “
Very few vaccines are given in a single dose because the second dose is needed to increase antibody levels, noted Akiko Iwasaki, an immunologist at Yale University. People who have been inoculated with the J. & J. The vaccine “relies on this primary response to maintain high levels of antibodies, which is difficult, especially against the variants,” she said.
Boosting immunity with a second dose should increase antibody levels enough to counteract the variants, she said.
Turning to an mRNA vaccine for the second shot, rather than another J. & J. shot, maybe better: Several studies have shown that combining one dose of AstraZeneca vaccine with one dose of Pfizer-BioNTech or Moderna vaccines stimulates the immune response more effectively than two doses of AstraZeneca.