Frontier "The Lancet" publishes "mixed inoculation" test results

With the advancement of new crown vaccination, whether mixed vaccination can be one of the public's concerns

Recently, "The Lancet" published the results of an important trial of mixed vaccination of the new crown vaccine

According to the research team, "This is the first study to evaluate the immune and cellular responses of mixed vaccination of the new crown vaccine

A review article published in the same period of The Lancet pointed out, “The findings of this study are promising.

More than a month ago, "The Lancet" published a Com-COV study led by the Oxford University team.

CombiVacS is a phase 2 randomized controlled trial conducted in five university hospitals in Spain

The main outcome of the test is the immunogenicity 14 days after the second injection, which is evaluated by measuring the level of antibodies against the new coronavirus S protein and S protein receptor binding domain (RBD), function (humoral immunity) and cellular immune response

The results showed that in the intervention group, the antibody level increased significantly after the second injection of mixed vaccination

Also on the 14th day, compared to only one shot, the antibody level after two mixed shots was also higher

According to the further analysis of the two-shot vaccination interval, the results are similar

▲The antibody titers of the intervention group (red) and the control group (blue) against RBD (A) and S protein (B) on the 0th, 7th and 14th days of the second injection

Among the 198 randomly selected subjects (129 in the intervention group and 69 in the control group), the research team analyzed the antibody function and observed that the second dose of mixed vaccination significantly improved the neutralizing ability of the antibody

In the intervention group, on day 0, 96 (74%) of the antibodies in the subjects showed no or very low neutralizing activity

On day 14, the geometric mean titer of neutralizing antibodies in the intervention group increased by 45 times (41.

▲The level of neutralizing antibody in the intervention group (red) and the control group (blue) at 0 and 14 days after the second injection, NT50 is the titer that achieves 50% neutralization

Next, the research team also observed that the T cell response was stronger in the mixed vaccinated population

The safety result of the study was the reactogenicity within 7 days of the second dose of mixed vaccination, and local and systemic adverse events were assessed in all subjects vaccinated with BNT162b2
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The results showed that most of the 1771 adverse events collected were mild (n=1210[68%]) or moderate (n=530[30%]) and were self-limiting
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The most frequently reported adverse events were injection site pain (n=395[88%]), induration (n=159[35%]), headache (n=199[44%]) and myalgia (n=194[43 %]), no serious adverse events were reported
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No difference was observed in the incidence of adverse events in different age groups
.

Based on these data, the research team believes that the second mixed injection of BNT162b2 after the ChAdOx1-S vaccine can induce a strong immune response and has acceptable and controllable safety characteristics
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In the future, it is necessary to directly compare the same vaccination and mixed vaccination to confirm the safety and effectiveness of the mixed vaccination strategy
.

Although affirming the hope and significance of mixed vaccination, the "Lancet" review article also pointed out the limitations of this study, such as the lack of two injections of the same vaccination as a control; the trial population also has strict inclusion criteria and limited representativeness; research samples The small amount and short follow-up time make it difficult to fully evaluate the safety of mixed vaccination programs
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But in general, the review article emphasizes that mixed vaccination will help speed up global vaccination and improve pandemic control, and this research should become the basis for future research
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Large-scale Phase 3 trials and further observational studies that use two injections of the same vaccine as a control will further tell us the clinical effectiveness and safety of mixed vaccination
.