What is the difference between the two injections of the new crown vaccine and the "mixed" antibody protection?

On July 14, local time, the New England Journal of Medicine (NEJM) recently published an important new crown vaccine "mixed" study, adding new evidence for the immunogenicity and safety of mixed vaccination

Compared with the preliminary safety data of the Com-COV test and the immune response data of the CombiVacS test published by The Lancet, this Swedish study more intuitively compared the effects of the antibody of the same type and the two injections

This is a phase 4 study to explore the immunogenicity of the new crown vaccine, and it is still ongoing

On the day of the second vaccination, 7-10 days and 30 days after the vaccination, blood samples of the subjects were obtained to analyze the levels of new coronavirus-specific IgG antibodies and the levels of neutralizing antibodies

On the day of the second injection, the two injections of ChAdOx1 nCoV-19 group and mixed group had similar levels of new coronavirus spike protein (S) specific and receptor binding domain (RBD) specific IgG antibodies, neutralizing Antibody levels are also similar

7-10 days after the second shot of vaccination, the S-specific and RBD-specific IgG antibody levels in the subjects of the two shots of ChAdOx1 nCoV-19 group were 5 times that of the second shot of vaccination (P<0.

Thirty days after the second vaccination, the levels of S-specific IgG antibodies in the two groups were still similar to the levels 7-10 days after the second vaccination

▲The level of S-specific (A) and RBD-specific (B) IgG antibodies in the two groups on the day of the second vaccination (P), 7-10 days and 30 days after vaccination

In the in vitro neutralization experiment against the original Swedish new coronavirus isolate (SARS-CoV-2/01/human/2020/SWE), it was observed by immunofluorescence that the neutralizing antibodies of the mixed group subjects The level is also higher

Compared with 7-10 days after the second shot of vaccination, one month after the second shot of vaccination, the neutralizing antibody titers of both groups increased by 1.

At the same time, the research team also used the cytopathic effect assay to measure the serum antibodies of the two groups of subjects 7-10 days after the second inoculation against the original isolate and the B.

At the same time, it was also found that the antibodies in the mixed group had an in vitro neutralization effect on the B.

▲The levels of neutralizing antibodies in the two groups of subjects

In terms of reactogenicity, the subjects who received the second injection of mRNA-1273 reported more fever, headache, chills, and muscle pain, but when grading the degree of adverse reactions (mild, moderate, severe), two There were no significant differences in group events

Based on these data, the research team mentioned in the paper that mixing the mRNA-1273 vaccine 9-12 weeks after the initial inoculation of ChAdOx1 nCoV-19 vaccine can effectively further stimulate the new coronavirus-specific B cell memory; moreover, the second shot Mixing the mRNA-1273 vaccine may provide better protection against the B.

The editorial podcast published by NEJM at the same time carefully interpreted these findings

Reference

[1] Johan Normark, et al.
, (2021).
Heterologous ChAdOx1 nCoV-19 and mRNA-1273 Vaccination.
The N Engl J Med, DOI: 10.
1056/NEJMc2110716

[2] Eric J.
Rubin, Lindsey R.
Baden, Stephen Morrissey.
(2021).
Monoclonal Antibodies and Vaccine Boosts.
The N Engl J Med, DOI: 10.
1056/NEJMe2111903