Experiments in the UK with the mixing of Covid vaccines

LONDON – A study is being launched in the UK to explore whether the use of different Covid-19 vaccines for the first and second doses works in an attempt to make national vaccination programs more flexible.

The process, led by Oxford University and led by the National Immunization Program Evaluation Consortium, will assess the feasibility of using a different vaccine for the initial “primary” vaccination to the follow-up “booster” vaccination.

It is hoped that the study will help decision-makers understand whether mixing different Covid vaccines could be a viable way to increase the flexibility of vaccination programs and even provide better protection.

“If we show that these vaccines can be used alternately in the same program, this will greatly increase the flexibility of vaccine administration and could provide clues on how to increase protection against new strains of the virus,” said Matthew Snape, chief investigator. on the trial and associate professor of pediatrics and vaccinology at Oxford University, he said on Thursday.

The process, officially known as the “COVID-19 Heterologous Prime Boost study” but dubbed the “Com-Cov” study, will recruit more than 800 volunteers over the age of 50 in England to assess the four different combinations. of booster vaccination.

He will test a first dose of Oxford-AstraZeneca vaccine followed by growth with either the Pfizer-BioNTech vaccine or an additional dose of Oxford-AstraZeneca vaccine. The research will also look at a first dose of Pfizer-BioNTech vaccine followed by an increase in either the Oxford-AstraZeneca vaccine or an additional dose of Pfizer-BioNTech vaccine.

These will be evaluated at two different dosing schedules: at an interval of four weeks to give an early reading of the intermediate data and at an interval of 12 weeks. This last dosing interval is the current vaccination policy in the UK: a delay in the second dose means that more people can get their first vaccines earlier, due to a small amount of vaccines.

Although the policy has proved controversial, some experts are concerned that it could make vaccines used in the UK less effective; So far, only candidates from Oxford-AstraZeneca and Pfizer-BioNTech are in use, with the Moderna set to be added to the vaccine basket that will be used later in the spring.

However, the University of Oxford published a study on Wednesday in which it showed that a 12-week delay between the first and second doses of AstraZeneca jab increases the effectiveness of the vaccine.

The researchers found that the shot was 76% effective in preventing symptomatic infection for three months after a single dose and that the effectiveness rate increased to 82.4% when there was at least a 12-week interval before the second dose. 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 study volunteers and monitor the impact of different dosing regimens on participants’ immune responses, as well as look for any additional side effects to new vaccine combinations.

The study will last 13 months and was supported by £ 7 million ($ 9.5 million) in government funding from the Vaccines Taskforce, which was set up by the UK in April last year to coordinate research and production efforts. of a coronavirus vaccine.

Professor Snape said the study was “extremely interesting” before adding that it would “provide vital information for the launch of vaccines in the UK and globally”.

Richer countries are struggling to vaccinate as many people as possible as national blockages, with the aim of limiting the spread of infections and preventing hospitals from overtaking, affecting economies.

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

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

The British government was quick to pre-order coronavirus vaccines from a variety of manufacturers early last year and approved the vaccines currently in use. Its vaccination program has been widely praised for its agility and coverage and aims to vaccinate 15 million people in the top four priority groups, including health and care workers, the elderly and over 70s, and anyone who is considered extremely clinically vulnerable in mid-February.

The latest government data, as of Wednesday, shows that just over 10 million people received their first dose of vaccine, and just under 500,000 had a second dose. The Oxford-AstraZeneca vaccine, produced in the UK, is the largest part of the UK vaccination program.

The deputy director of the doctor and senior head of the study, Professor Jonathan Van-Tam, said the research could even show that alternating vaccines could increase the level of antibodies needed to fight potential Covid-19 infection.

“It is also possible that by combining vaccines, the immune response can be improved by providing even higher levels of antibodies that last longer; unless this is assessed in a clinical study, we simply will not know. This study will give us a better perspective on how we can use vaccines to stay at the forefront of this ugly disease, “he said.

The British Minister of Vaccines, Nadhim Zahawi, told the BBC on Thursday that, for the time being, the country’s vaccination program will continue normally: “At this moment we will not change anything at all”, Zahawi declared for the “Today” program.

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