The National Health Service (NHS) of the United Kingdom has been performing experiments to determine the efficacy of mixing two separate vaccines. The aim of this 13-month trial is to determine how well the immune systems of individuals react after being "primed" with one form of the vaccine and then enhanced with another.

The trial phase

According to experts, this is only a trial and it is unclear if it would be beneficial. As more COVID-19 vaccinations rise globally, analysts have wondered if vaccines can be mixed and balanced to increase vaccination rates. Due to evidence of vaccine supply chain problems, encouraging people to use a variety of vaccines can help them get completely vaccinated more quickly. The National Health Service (NHS) is undertaking experiments to determine the efficacy of integrating two separate COVID-19 vaccinations in an effort to develop more flexible COVID-19 vaccination services. The research is called the Com-COV study, and it raises critical concerns, such as whether this will improve or decrease vaccine efficacy.

How is the Com-COV trial conducted?

• The aim of this 13-month experiment, according to the NHS, is to determine how well people's immune systems react after being "primed" with one kind of vaccine and then enhanced with another.
• The researchers want to determine the strength of the immune system response when the second dose is given at a different time interval from the first dose.
• Additionally, researchers will monitor the effect of various dosing regimens on participants' immune system responses and check for any additional adverse effects to these vaccine combinations.
• AstraZeneca and Pfizer-BioNTech provided the vaccines used in this research. The NHS did add that, if additional vaccines are authorised for use in the United Kingdom after this research begins, they will be included in the experiment.

It's important to remember that, according to the most recent recommendations from the Centers for Disease Control and Prevention (CDC) Trusted Source, due to a lack of acceptable safety evidence, COVID-19 vaccines cannot be combined unless an unusual circumstance exists, such as a vaccine deficit for the individual who initially got the vaccine.

There are two distinct types of pneumococcal vaccinations with distinct modes of action, although under some circumstances, combining them can be considered sometimes. AstraZeneca and Pfizer-BioNTech vaccines work differently. The vaccines defend against COVID-19 using two distinct technologies. The vaccine developed by Pfizer and BioNTech is an mRNA vaccine, but the vaccine developed by AstraZeneca is not.

How do the vaccines work?

AstraZeneca, like Johnson & Johnson, uses adenovirus vector technology. However, all vaccines contain instructions directing our cells to produce the SARS-CoV-2 virus's spike protein, which is responsible for COVID-19. This then triggers our bodies to mount an immune reaction against the coronavirus spike antigen, which aids in protecting us if we are infected. The distinction is in the manner in which the two vaccines provide these directions to our cells.

Pfizer delivers information into cells through mRNA coated in lipid (fatty) material although AstraZeneca accomplishes the same thing by using a diluted strain of adenovirus- a common cold virus. Both vaccines require two doses at the moment. While the modified virus in AstraZeneca's vaccine is not infectious, it contains a gene from the coronavirus's spike protein, the part of the virus that initiates an immune response.

As a consequence, the immune system produces antibodies that are specific for COVID-19, instructing the body on how to react if an infection occurs. The hybrid approach's efficacy is unknown. However, the trial provides useful details. It is a novel strategy, which is why the United Kingdom has proposed conducting a feasibility review to assess it. It is conceivable that delivering the information to the cells in two distinct ways (via mRNA and via an adenovirus viral vector) results in a stronger or longer protective response. However, this technique can jeopardize or enhance overall efficacy. This method is more applicable in the sense of analysis because of the issue of whether it would be better or worse. This trial would shed more light.

Combining vaccinations that aren't yet ready for prime time

Combining vaccines is not yet ready for prime time, according to an expert. Without a doubt, critical COVID-19 vaccine shortages exist. It is a real question if we can address these problems in order to protect the majority of the population from the pandemic and return to a more natural state. However, is combining separate vaccines preferable to missing a necessary second dose? To reach 90 per cent effectiveness, the second dose should be administered. However, in emergency situations, such as where there is a lack of COVID vaccines, it would be preferable to vaccinate more patients with a single dose. At the very least, any defence is preferable to zero.

The gist

• Researchers in the United Kingdom are running a clinical trial to determine whether combining the Pfizer-BioNTech and AstraZeneca vaccines will further maximise the number of patients who will receive the necessary two doses of COVID-19 vaccine.
• According to experts, there is insufficient evidence to determine if this strategy is successful, and it could also reduce the level of security provided by these vaccines.
• Except under rare cases, the CDC currently warns against combining vaccines.
• According to researchers, in cases where mixing multiple COVID-19 vaccinations or not receiving the second dose is not an option, it is preferable to use the same vaccine in a single dose before more information becomes available.

Disclaimer- The views and opinions expressed in this article are those of the author's and do not necessarily reflect the official policy or position of M3 India.

The author, Dr. Monish S Raut is a Consultant in Cardiothoracic Vascular Anaesthesiology. His area of expertise is perioperative management and echocardiography with numerous publications in various national and international indexed journals.