Will new vaccines be more effective in fighting coronavirus variants? | Kiowa County Press

Dozens of coronavirus vaccines are in clinical trials in the United States João Paulo Burini/Moment via Getty Images

Vaibhav Upadhyay, University of Colorado Anschutz Medical Campus and Krishna Mallela, University of Colorado Anschutz Medical Campus

The first three coronavirus vaccines were granted emergency use authorization more than a year ago. To date, no other vaccines have been fielded in the United States – but that will soon change. More than 40 vaccines are in clinical trials in the United States, using a number of different approaches to protect people from the coronavirus. Vaibhav Upadhyay and Krishna Mallela have been studying the coronavirus spike protein since the outbreak of the pandemic and developing COVID-19 therapies. Together they explain which vaccines are in development and why certain vaccines should be better than those currently available.

1. Why are companies working on new vaccines?

One of the main reasons why new vaccines matter – and why the world is still dealing with COVID-19 – is the continued emergence new variants. Most of the differences between the variants are changes in spike proteinwhich sits on the surface of the virus and helps it enter and infect cells.

Some of these small changes in the spike protein allowed the coronavirus to infect human cells more efficiently. These changes have also made previous vaccinations or infections with COVID-19 offer less protection against new variants. Updated or new vaccines could better detect these different spike proteins and better protect against the new variants.

A number of vaccine vials on a production line.
Vaccines generally fall into four categories: whole virus vaccines, viral vector vaccines, protein-based vaccines, and nucleic acid-based vaccines. Andriy Onufriyenko/Moment via Getty Images

2. What types of vaccines are in preparation?

Until now, 38 vaccines have been approved worldwide, and the United States has approved three. There are currently 195 vaccine candidates at different stages of development around the world, including 41 are in clinical trials in the United States SARS-CoV-2 vaccines can be broadly divided into four classes: whole virus, viral vector, protein-based and nucleic acid-based vaccines.

Whole-virus vaccines generate immunity using a complete, albeit weakened, SARS-CoV-2 virus – called inactivated or attenuated. Currently, two of these vaccines are in clinical trials in the United States. Viral vector vaccines are a variation of this approach. Instead of using the whole coronavirus, they’re using a modified version of a harmless adenovirus that carries parts of the coronavirus spike protein. The Johnson & Johnson vaccine is a viral vector vaccine, and there are 15 other candidates in this category in clinical trials in the United States.

Protein-based vaccines use only the spike protein or part of the spike protein to generate immunity. Since the spike protein is one of the most functionally important parts of the coronavirus, an immune response that targets only this part is enough to prevent or defeat an infection. The United States currently has five protein-based vaccines in clinical trials.

Nucleic acid vaccines are currently the most widely used in the United States. They are made up of genetic material, such as DNA or RNA, which codes for coronavirus spike protein. Once a person receives one of these vaccines, their body reads the genetic material and produces the spike protein. This in turn generates an immune response. There are 17 RNA and two DNA vaccines in clinical trials in the United States Some of them use the genetic material of new variants, including updated versions of Moderna and Pfizer vaccines.

3. Will new vaccines be better than existing vaccines?

Moderna, Pfizer and J&J vaccines are based on the original strain of coronavirus and are less powerful against new variants. Vaccines based on new variants would offer better protection against these new strains than existing vaccines, and some are in development. Nucleic acid vaccines are the easiest to update and constitute the majority of variant-targeted vaccines. Moderna has already produced a vaccine that contains mRNA of beta and omicron variantsand some recently published clinical data shows it is more effective against newer variants than Moderna’s original vaccine.

Although it is important to update nucleic acid vaccines, some research suggests that viral vector or whole virus vaccines could be more effective against new variants – without the need for updates.

A model of the coronavirus.
Whole-virus vaccines use an inactivated, harmless version of the coronavirus – seen here – to produce a strong immune response. Alexey Solodovnikov, Valeria Arkhipova via WikimediaCommons, CC BY-SA

4. What are the benefits of whole virus vaccines?

Nucleic acid-based and protein-based vaccines use only the spike protein to produce an immune response. With a whole-virus vaccine, the immune system not only recognizes the spike protein, but also all other parts of the coronavirus. The other parts of the virus help to quickly generate a strong immune response that involves many branches of the immune system and lasts a long time.

Another advantage of whole virus and virus vector vaccines is ease of storage and shipping. Viral vector vaccines can be stored in common household refrigerators for months, sometimes years. In comparison, Moderna and Pfizer mRNA vaccines should be stored and shipped at ultra-low temperatures. These infrastructure requirements make whole-virus vaccines much more feasible for use in remote locations in the United States, as well as around the world.

5. What are the disadvantages of whole virus vaccines?

Whole virus vaccines have some disadvantages.

To produce inactivated virus vaccines, you must first produce a huge amount of live coronavirus and then inactivate it. There is a low but legitimate biological risk associated with the production of many live coronaviruses. A second disadvantage is that virus vaccines and inactivated viral vectors may not produce strong protection in immunocompromised patients.

Finally, the production of whole virus vaccines is much more labor intensive than the manufacture of mRNA vaccines. You need to grow, then purify and then inactivate the virus while carefully checking the quality at every step. This lengthy production process makes it difficult to produce large quantities of vaccine. For the same reasons, redesigning or updating whole-virus vaccines for future variants is more difficult than just change the nucleic acid code or a protein-based vaccine.

By examining the pros and cons of each type of vaccine, we believe that virus-based vaccines could play an important role in generating widespread and long-lasting immunity against a rapidly mutating virus. But easily updated mRNA or protein-based approaches that can be adapted to the latest variants may also be key to containing the spread of the pandemic. With vaccines of all types in the works, public health officials and governments around the world will have more tools at their disposal to deal with whatever the coronavirus brings next.

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The conversation

Vaibhav Upadhyaypostdoctoral fellow in pharmaceutical sciences, University of Colorado Anschutz Medical Campus and Krishna Mallelaprofessor of pharmaceutical sciences, University of Colorado Anschutz Medical Campus

This article is republished from The conversation under Creative Commons license. Read it original article.

About Florence M. Sorensen

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