"The Lancet" publishes preliminary safety data of "mixed inoculation" trial

In order to alleviate the challenges of insufficient supply of the new crown vaccine, the strategy of "mixed vaccination" of different vaccines has attracted international attention.

Today, "The Lancet" recently published important data from a large randomized trial in the United Kingdom, by evaluating the combination of AstraZeneca's new crown vaccine ChAdOx1 nCoV-19 and Pfizer/BioNTech's new crown vaccine BNT162b2, and analyzing the local subjects after vaccination And systemic reactions, as well as laboratory blood and biochemical test results, provide preliminary data for the safety of mixed vaccination.

The Com-COV study, led by the Oxford University team, is a multi-center, single-blind, randomized, heterologous prime-boost (heterologous prime-boost) new crown vaccination study in the United Kingdom.

The study used a two-dose vaccination protocol (first injection [prime], second injection [-boost]), and compared the two vaccines BNT162b2 (hereinafter referred to as BNT) and ChAdOx1 nCoV-19 (hereinafter referred to as ChAd).

A total of 830 subjects were enrolled in the study, all of whom were 50 years of age and older, and had no comorbid diseases, or the comorbid diseases were only mild to moderate and well-controlled.

A total of 463 subjects received 28 days between the two doses.

The results showed that in the population who used the same two-dose vaccine regimen, the recorded systemic reactogenicity was higher after the first injection in the ChAd group and the second injection in the BNT group.

Compared with two doses of the same vaccine, the two mixed vaccination regimens caused more obvious systemic reactions after the second dose.

Take the report of self-feeling fever (feverish) as an example:

Among the vaccinators of the ChAd/BNT combination, 34% (37 cases/110 cases); among the two injections of ChAd vaccinators, 10% (11 cases/112 cases), the absolute difference in the proportion of vaccinators with this reaction was 24% (95% CI 13%-35%).

Among the vaccinators of the BNT/ChAd combination, 41% (47 cases/114 cases); among the two injections of BNT vaccinators, 21% (24 cases/112 cases), the absolute difference in the proportion of vaccinators with this reaction was 21% (95% CI 8%-33%).

Similar trends were observed in chills, fatigue, headaches, joint pain, discomfort, and muscle aches.

The local reactions in the picture include: hardening, itching, pain, redness, swelling, and warmth at the injection site.

The severity was mild, moderate, severe, and hospitalized.

Before the start of the study, the subjects had been told that acetaminophen might reduce the side effects of the vaccine, but the researchers did not actively recommend them to take preventive medication.

Two injections of ChAd: 36% (40 cases/112 cases),

ChAd/BNT combination vaccination: 57% of the medications (63 cases/110 cases),

Two injections of BNT: 41% of the medications (48 cases/117 cases),

Vaccination of BNT/ChAd combination: the proportion of medication is 60% (68 cases/114 cases).

The paper pointed out, "It is particularly noteworthy that these data were obtained in subjects over 50 years old, and in younger people, the reactogenicity may be higher.

Between the two injections of the same vaccine and the two vaccine mixed vaccination regimens, the hematological and biochemical characteristics of the vaccinated persons are similar.
All laboratory adverse events in the mixed vaccination regimen were grade 2 or lower; on the 7th day after the second booster vaccination, there was no thrombocytopenia in any group.

The paper concludes that “before obtaining more complete safety data and immunogenicity results, these data indicate that the mixed vaccination regimen used in the Com-COV study may have some short-term effects, and acetaminophen can help alleviate these symptoms.
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But it can be assured that all reactogenic symptoms are short-lived, and the limited hematology and biochemical test data do not cause concern.
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The corresponding author of the study, Dr.
Matthew Snape, professor of vaccinology at the University of Oxford, added, “It is important that (the mixed vaccination regimen used in the study) has no safety issues or signals, but this does not tell us whether the immune response will be affected.
Report these data in the next few months.
"

At present, the Com-COV study is continuing to evaluate the long-term impact of the mixed vaccination regimen of BNT162b2 and ChAdOx1 nCoV-19.
Among them, the main immunological results data are expected to be announced in June 2021, and the study will add additional analysis, acetaminophen Will preventive medication or conventional medication reduce these reactions? In addition, the research team will also evaluate other available new crown vaccine combinations.
It is hoped that longer-term data can further provide reference for mixed vaccination.