Vaccine Modification for Variants of Diseases

Corresponding Author:

Shobitha Arham
Department of Pharmaceutics,
University of Khinaliq,
Khinaliq,
Azerbaijan
E-mail: shobith.arh@gmail.com

Received: 16-Jul-2024, Manuscript No. ACTVR-24-141878; Editor assigned: 19-Jul-2024, Pre QC No. ACTVR-24-141878 (PQ); Reviewed: 02-Aug-2024, QC No. ACTVR-24-141878; Revised: 07-Aug-2024, Manuscript No. ACTVR-24-141878 (R); Published: 12-Aug-2024, DOI: 10.37532/ ACTVR.2024.14(4).273-274

Introduction

Vaccines have been one of the most effective tools in combating infectious diseases, saving millions of lives globally. However, as viruses evolve and mutate, new variants emerge, posing challenges to existing vaccines. This necessitates the modification of vaccines to ensure they remain effective against these variants. Understanding the science behind these modifications and how they are tailored to tackle different variants of diseases is crucial in the ongoing fight against viral outbreaks.

Description

Viral evolution and the emergence of variants

Viruses, particularly RNA viruses like influenza, coronaviruses (such as SARS-CoV-2), and HIV, tend to mutate frequently. These mutations occur when a virus replicates, leading to slight changes in its genetic code. While many mutations are benign, some can alter the virus’s behavior, increasing its ability to spread, evade the immune system, or resist treatment.

A variant is a version of the virus with a particular set of mutations. These variants may differ from the original strain in their transmissibility, severity of infection, or susceptibility to vaccines. For instance, the Delta and Omicron variants of COVID-19 are notable for their increased transmission rates compared to the original strain.

Why vaccine modification is necessary

Vaccines work by priming the immune system to recognize and fight specific parts of a virus, typically its spike proteins or other surface proteins. When a virus mutates significantly, these proteins may change, reducing the ability of the immune system to recognize and neutralize the virus. In such cases, the original vaccine may lose some of its effectiveness, necessitating modifications to the vaccine.

The necessity for vaccine modifications can be driven by:

• Increased transmissibility of the variant.
• Vaccine escape mutations, where variants can partially or completely evade the immune response triggered by the original vaccine.
• Reduced protection against severe disease or infection in vaccinated individuals.

Mechanisms of vaccine modification

Modifying a vaccine to counter a new variant can take various approaches. The strategies largely depend on the type of vaccine platform used, such as mRNA, viral vector, or protein subunit vaccines. Below are common techniques for vaccine modification:

Updating mRNA vaccines: The most prominent example of mRNA vaccines is the Pfizer- BioNTech and Moderna COVID-19 vaccines. These vaccines use mRNA to instruct cells to produce a viral protein that triggers an immune response. Modifying an mRNA vaccine involves changing the sequence of the mRNA to match the protein structure of the new variant. This allows the vaccine to induce immunity against the modified virus. The rapid development and flexibility of mRNA technology make it easier and faster to update compared to traditional vaccines.

Viral vector vaccines: Viral vector vaccines, like the Johnson & Johnson and AstraZeneca COVID-19 vaccines, use a harmless virus to deliver genetic material from the virus’s spike protein into cells. To modify these vaccines for variants, scientists can swap the genetic code for the spike protein with that of the variant. However, viral vector vaccines take longer to modify and produce than mRNA vaccines.

Protein subunit vaccines: These vaccines use purified proteins from the virus to elicit an immune response. Modifying such vaccines involves producing new versions of the viral protein, matching those present in the variant. This method is used in vaccines for diseases like hepatitis B and Human Papillomavirus (HPV).

Challenges in vaccine modification

While modifying vaccines for new variants is scientifically feasible, several challenges arise:

Predicting mutations: Viruses mutate unpredictably, and vaccine developers must strike a balance between targeting the current variants and preparing for potential future ones. Predicting which mutations will become dominant and how they will affect vaccine effectiveness is a complex task.

Regulatory approvals: Any modification to an existing vaccine must go through regulatory scrutiny to ensure it is safe and effective. This process, though expedited in some cases (such as with COVID-19 vaccines:, still takes time, which can delay the deployment of modified vaccines.

Manufacturing and distribution: Once a vaccine is modified, producing it at scale and distributing it to populations remains a logistical challenge, especially in low-resource settings. Vaccine production involves complex manufacturing processes that can be difficult to adjust quickly.

Public hesitancy and communication: Convincing the public of the need for modified vaccines can be challenging. Misinformation, vaccine hesitancy, and pandemic fatigue may hinder widespread acceptance of updated vaccines, reducing their overall impact.

Examples of modified vaccines

Several vaccines have been successfully modified to address emerging variants:

Influenza vaccines: Every year, influenza viruses undergo antigenic drift, leading to new strains. As a result, flu vaccines are updated annually to match circulating strains, based on predictions from global surveillance networks. The World Health Organization (WHO) recommends the composition of flu vaccines each season to ensure optimal protection against the predicted dominant strains.

COVID-19 vaccines: With the emergence of variants like Delta and Omicron, efforts were made to update COVID-19 vaccines. Pfizer- BioNTech and Moderna have developed bivalent boosters that target both the original strain and newer variants like Omicron. These modifications have shown enhanced protection against variantspecific infections while maintaining safety and efficacy.

HIV vaccine research: Though no HIV vaccine has been successfully developed yet, efforts are underway to create vaccines that can tackle the high mutation rate of the virus. mRNA technology and protein subunit vaccines are being explored to produce a vaccine capable of targeting multiple HIV variants.

Conclusion

The production of drugs is a complex and multifaceted endeavor, fraught with numerous challenges that span scientific, regulatory, economic, and ethical dimensions. Despite these challenges, the pharmaceutical industry continues to innovate and develop new treatments that improve and save lives. Addressing these challenges requires a collaborative effort among researchers, manufacturers, regulators, and policymakers. By working together, stakeholders can overcome the hurdles in drug production and ensure.