British pilot experiments with mixing Covid vaccines

LONDON – A trial is underway in the UK to investigate whether the use of different Covid-19 vaccines for the first and second dose works to make nationwide vaccination programs more flexible.

The trial, led by the University of Oxford and conducted by the National Immunization Schedule Evaluation Consortium, will evaluate the feasibility of using a different vaccine for the first “first” vaccination to the follow-up “booster” vaccination. .

It is hoped that the research will help policymakers understand whether mixing different Covid vaccines could be a feasible way to increase the flexibility of vaccination programs and whether it could even provide better protection.

“If we demonstrate that these vaccines can be used interchangeably on the same schedule, it will significantly increase the flexibility of vaccine delivery and provide guidance on how to broaden the breadth of protection against new strains of virus,” said Matthew Snape, Lead researcher. on the trial and associate professor of Pediatrics and Vaccinology at the University of Oxford, said Thursday.

The study, formally known as the “COVID-19 Heterologous Prime Boost Study” but referred to as the “Com-Cov” study, will recruit more than 800 volunteers aged 50 and over in England to study the four different combinations of prime and booster vaccination.

It will test a first dose of the Oxford AstraZeneca vaccine, followed by a boost with either the Pfizer-BioNTech vaccine or a further dose of the Oxford AstraZeneca vaccine. The study will also look at a first dose of the Pfizer-BioNTech vaccine, followed by a boost with either the Oxford-AstraZeneca vaccine, or a further dose of the Pfizer-BioNTech vaccine.

These will be evaluated according to two different dosing schedules: at an interval of four weeks to obtain an early intermediate data reading, and at an interval of 12 weeks. This last dosing interval is the current vaccination policy in the UK: a delay of the second dose means that more people can get their first vaccines sooner amid a tight supply of injections.

While the policy was seen as controversial, some experts feared it could make vaccines used in the UK less effective; Only the University of Oxford-AstraZeneca and Pfizer-BioNTech candidates are in use so far, and the Moderna shot set will be added to the vaccine basket later in the spring.

However, the University of Oxford published a study on Wednesday showing that a 12-week delay between the first and second dose of the AstraZeneca shot increases the vaccine’s efficacy.

The researchers found that the injection was 76% effective in preventing symptomatic infection for three months after a single dose, and that the effectiveness increased to 82.4% when there was at least a 12-week interval for the second dose. When the second dose was given less than six weeks after the first, the efficacy rate was 54.9%.

In the latest “Com-Cov” study, researchers will collect blood samples from trial volunteers and monitor the impact of different dosing regimens on the immune response of the participants, as well as looking for any additional side effects of the new vaccine combinations.

The study will run for 13 months and is supported by £ 7 million ($ 9.5 million) in government funding from the Vaccines Task Force, set up by the UK in April to coordinate research and produce a coronavirus vaccine.

Professor Snape said the research was “hugely exciting” before adding that “it will provide information essential for the introduction of vaccines in the UK and worldwide.”

Richer countries are doing their best to vaccinate as many people as possible because national lockdowns, designed to limit the spread of infections and prevent hospitals from being inundated, damage economies.

The UK has been hit hard by the pandemic and has seen cases of increases in the winter, aided by a more virulent variant of the virus emerging in south-east England, which has now become a dominant strain in the country.

The UK currently has the fourth highest number of cases in the world, with more than 3.8 million confirmed infections, according to a figure from Johns Hopkins University, and has recorded 109,547 deaths.

The UK government quickly ordered coronavirus vaccines from several manufacturers early last year and approved the vaccines currently in use. The vaccination program is widely acclaimed for its agility and reach, and it is on track to vaccinate 15 million people in the top four priority groups, including health and care providers, the elderly and the over 70s and anyone considered extremely clinically vulnerable. through mid-February.

The latest government data, as of Wednesday, shows that just over 10 million people have had their first vaccination dose, and just under 500,000 have also had a second dose. The Oxford AstraZeneca vaccine, which is manufactured in Great Britain, makes up the bulk of the UK vaccination program.

Deputy Chief Medical Officer and Senior Responsible Officer for the study, Professor Jonathan Van-Tam, said the study could even show that alternating vaccines can increase the level of antibodies needed to fight potential Covid-19 infection.

“It is even possible that by combining vaccines the immune response can be boosted, yielding even higher antibody levels that last longer; unless this is evaluated in a clinical trial, we just don’t know. This study will give us more insight into how we can use vaccines to keep abreast of this nasty disease, ”he said.

British vaccines minister Nadhim Zahawi told the BBC on Thursday that the country’s vaccination program will continue as normal for now: “At this point, we will not change anything at all,” Zahawi told the “Today” program.

“If you have had a Pfizer BioNTech vaccine for your first dose, you will receive a Pfizer BioNTech vaccine for your second dose. If you have had Oxford AstraZeneca, you will receive Oxford AstraZeneca for your second dose.”