Experiment on Novavax, AstraZeneca, Valneva, J&J, Moderna, CureVac, Pfizer. Participants had already received two doses of AstraZeneca or Pfizer
Seven anti Covid vaccines compared for the third dose. the study of a group of researchers from the English University of Southampton, Imperial College of London and the University of Oxford, who evaluated the possibility of a booster with a different vaccine from the one used for the first two injections. The work was published on Lancet
. 2,878 people over the age of 30 (with no history of laboratory-confirmed SARS-CoV-2 infection) were given booster, at least 70 days after two doses of AstraZeneca or at least 84 days after two doses of Pfizer- BioNTech (10-12 weeks). The safety, immunogenicity and tolerability of the vaccines were evaluated in the experiment Novavax, AstraZeneca, Valneva, Johnson & Johnson (J&J), Moderna, CureVac, Pfizer. Participants in the COV-BOOST study were divided into 3 groups and within each the participants were randomly assigned to a vaccine or control: people in group A received one dose of Novavax, half dose of Novavax, AstraZeneca or the menACWY quadrivalent meningococcal vaccine (as a control); those in group B received Pfizer, Valneva, half dose of Valneva, J&J or MenACWY; those in group C received Moderna, CureVac, half a dose of Pfizer or MenACWY.
Vaccines at mRna
All vaccines produced a strong immune response in booster, although the data varies depending on the combination. The mRna vaccines appear to produce a greater increase in antibodies and T lymphocytes, when given 10-12 weeks after the second dose (regardless of whether the person initially received Pfizer or AstraZeneca). Also the booster with AstraZeneca, Novavax, Johnson & Johnson and Curevac increased antibody levels. Valneva it boosted defenses in people initially vaccinated with AstraZeneca, but did not perform well in those who received two doses of Pfizer. The increase in antibodies and T cells occurred in both age groups of the participants (30-69 years and over 70) and towards all circulating variants, including Delta (Omicron had not yet appeared). The work, the scientists point out, has examined the immune response and not efficacy in protecting against infection or serious illness. The two parameters, they observe, are closely related to each other, but remain distinct anyway, so it will still be necessary to investigate further. According to what we know so far, the two-dose cycle with AstraZeneca and Pfizer associated with a protection of 79 and 90 per cent respectively against hospitalization and death from Covid, but the ability to fight infection appears to decrease after a few months. In the next works the research group will evaluate the effectiveness of booster 3-12 months after administration.
Side effects
All seven vaccines are safe as a third dose – he said Saul Faust, who conducted the trial at Southampton University Hospital – National Institute for Health Research -, with acceptable levels of side effects such as pain at the injection site, muscle soreness, fatigue. All vaccines enhanced immunogenicity after two doses of AstraZeneca, while patients immunized with Pfizer had effective responses with the third dose of AstraZeneca, Pfizer, Moderna, Novavax, Johnson & Johnson and Curevac; the recall with Valneva was less effective. Three vaccine combinations showed an overall increase in reactogenicity (local or systemic adverse reactions): third dose of Moderna after two of AstraZeneca or Pfizer; third dose AstraZeneca or J&J after Pfizer. Fatigue and pain were the most common reactions, usually within 7 days of injection. A total of 24 serious adverse events occurred, including 5 in the control group.
Half dose Pfizer
The authors spoke of large variations in cellular and antibody immune responses between different vaccines, but vaccines that boosted immunity gave good results in all age groups, including over 70s. In people who had received two doses of AstraZeneca, a 30-fold increase in antibody levels was seen after a Moderna booster and a 25-fold increase after a Pfizer booster. Even after two doses of Pfizer, which offers higher basic protection than AstraZeneca, the same mRna vaccines have dramatically increased antibody levels. Not only that: if in some countries stocks were to be scarce, according to the researchers you could use it for the booster half Pfizer dose, which was already effective in the study (the half dose of Moderna was not tested for logistical reasons). very encouraging to see that a wide range of vaccines benefit with the third dose, both after AstraZeneca and after Pfizer – concluded Saul Faust -. These findings give us confidence and provide flexibility in developing recall programs globally. To date, the AstraZeneca vaccine has been distributed in more than 180 countries and Pfizer in more than 145 countries.
December 5, 2021 (change December 5, 2021 | 19:01)
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