UK tests 3,000 vaccinated with AstraZeneca and Pfizer a third dose from seven different companies

How long do antibodies last? against SARS-CoV-2, the virus that causes covid-19, in the human organism is still one of the unknowns that science has not resolved due to obvious reasons of lack of time. To this are added the new variants that are emerging of the coronavirus, which could jeopardize the efficacy of vaccines, although the WHO has stated that all sera protect against all strains known so far. These two reasons have led to UK, where 70% of the population already has the least the first dose and almost 40% have the complete regimen, to take the initiative and begin to study the adverse effects and the immune response of a future third booster dose.

The study was presented last Thursday, International Day of Clinical Trials, by the British Minister of Health, Matt Hancock. “This trial will look at the use of current covid vaccines as booster vaccines and what role can they play to keep us safe“, he claimed.

Who is going to participate?

The rehearsal will begin in June and will feature 2,886 participants older than 30 years and vaccinated with the first dose between December 2020 and January 2021. These are the requirements to be able to volunteer in this study that will be carried out in 16 hospitals and health centers throughout the country of the National Health System (NHS) and that will have a public budget of 22 , 4 million euros (19.3 million pounds).

Participants must also have received the second dose at least 70-84 days before starting the study, so the majority of people who qualify to become volunteers are older people who have already taken the two doses of the vaccine for between two and three months (over 75 years and health workers, mainly).

What vaccines are to be tested?

In the study, called ‘CovBoost’, both the adverse effects and the immune response of the combination of vaccines AstraZeneca y Pfizer/BioNTech, which are those that have been used in the United Kingdom to immunize its population with the first and second doses, with a total of seven vaccines against covid-19, both approved and in the evaluation process.

The seven covid vaccines that will be used in this trial are ChadOx1 nCoV-19 (the one developed at Oxford and manufactured by AstraZeneca), the BNT162b2 (manufactured by Pfizer and BioNTech), mRNA-1273 (manufactured by Modern), la NVX-CoV2373 (fabricada por Novavax), the VLA2001 (manufactured by Valneva), CVnCoV (manufactured by Curevac) and Ad26.COV2.S (developed by Janssen).

In addition, the meningococcal vaccine Men ACWY, which will be administered to the people who make up the control group.

Three of the covid vaccines used are currently UK regulatory (MHRA) approved, two are under review for approval and two others are still in clinical trials, but may be available in the UK. this 2021, the developers of the test, the first in the world of these characteristics, have explained.

Study of different ‘cocktails’

The researchers have pointed out that the volunteers do not have to receive the third booster dose of the same vaccine with which they received the first two pricks, so this study will evaluate multiple combinations of different covid-19 vaccines.

It should be remembered that the United Kingdom has already carried out a study to observe different combinations of the AstraZeneca and Pfizer vaccines and whose results, published in The Lancet, they showed a increased adverse effects, but all mild. Although this study did not address the immune response and was carried out in those over 50 years of age.

Spain has also evaluated the combination of a first dose of AstraZeneca and a second dose of Pfizer in children under 60 years of age and it has concluded that the adverse effects are still mainly mild, remit after 48 hours and the antibodies with neutralizing capacity increase by seven with respect to the first dose.

Half-dose study to increase delivery

This studio will also evaluate half doses of the Novavax, Valneva and Curevac vaccines. “This is important, because if this were effective, it could allow twice the number of vaccines to be given with the same vaccine supply. We are also studying whether half the dose of these vaccines causes fewer common side effects, such as fever or pain in the arm, while providing an adequate boost to the immune response “, they detail in the presentation of the study.

Deadlines and results

The study will start in June and expects to have the first preliminary results in September, before the next cold months arrive and it is possible, based on the evidence it provides, to make decisions to protect the population most at risk from covid-19 for next autumn.

“We will do everything we can to prepare this country for the future in the face of pandemics and other threats to our health security, and data from this first global clinical trial will help shape plans for our booster program later this year“Hancock pointed out.

The study will be extended for a year and the almost three thousand participants – an amount likely to be expanded as new vaccines against covid-19 become available.

Volunteers will undergo a blood tests 28 days after the third booster dose, 84 days, 308, and 365 days later, to evaluate the continuity of the antibodies and to monitor their neutralizing capacity against the coronavirus.


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