Vaccines for emerging infectious diseases

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Vaccines for emerging infectious diseases

The rapid spread presents new hurdles for vaccine development, regulation, and distribution. While speed is crucial, ensuring safety, monitoring for variants, and equitable access are equally important.

In the last fifteen years, there have been many new infectious diseases. Each time a new disease appears, there’s a need for quick vaccine development. It discusses the difficulties in making vaccines and how we test them to ensure they work against constantly changing diseases.

Emerging and Re-emerging Infectious Diseases

New infectious diseases have existed for ages, even before we knew what caused them. Despite progress in making tests, treatments, and vaccines, global travel and connections between countries make controlling these diseases harder. As human communities grow, there are more chances for new diseases to appear. A list of some infectious diseases that  have emerged over the years is given below:

• Yellow Fever: A disease spread by mosquitoes, common in Africa and South America. There have been outbreaks in countries like Angola, Congo, Nigeria, and Brazil. There are vaccines available, but there have been concerns about having enough supply.
• Dengue: Another mosquito-borne disease that is spreading in many countries. Around 400 million people get dengue each year, with up to 22,000 deaths. One vaccine, Dengvaxia, is licensed in many countries but not widely used due to safety concerns.
• Cholera: A bacterial disease causing severe diarrhea, often in Asia and Africa. Antibiotic resistance is growing, making treatment more challenging. Vaccines are available and used during outbreaks.
• Typhoid fever:  A severe bacterial disease with more drug-resistant strains, especially in Pakistan and India. New vaccines are being developed to fight these resistant strains.

Vaccines for Emerging Infectious Diseases Overview

New infectious diseases have threatened humanity for a long time; the following are the details mentioned about developing vaccines for emerging diseases.

• Factors like population growth, urbanization, and travel contribute to the spread of infectious diseases.
• The COVID-19 pandemic, caused by the SARS-CoV-2 virus,  had a significant impact worldwide, leading to millions of infections and deaths.
• Vaccines offer the best hope for controlling pandemics like COVID-19.
• This highlights the need for better surveillance, management, and global cooperation to control future disease threats.

Quick COVID-19 Vaccine Development: Key Factors

Vaccine development usually takes 5 to 10 years, but this is too slow during an epidemic. The Ebola outbreak in 2014 lasted over two years, allowing time to develop and test vaccines. However, with COVID-19, the entire process, from sequencing the virus to testing vaccines, took under 300 days.

COVID-19 vaccines developed in under a year is a significant scientific achievement, sparking hope for future vaccine advancements. Below are the key highlights behind the success of COVID-19, and this model can be used for other emerging infectious diseases.

• New Technologies: mRNA, viral vector technologies, and recombinant protein approaches were important in quick vaccine development.
• Helpful in  Other Diseases: These new vaccine platforms may also benefit diseases like HIV, malaria, and tuberculosis (TB), although success isn’t guaranteed.
• Funding and Support:  Funding accelerated vaccine development, allowing for simultaneous preclinical studies, trials, and manufacturing.
• Future Investments: Increased funding for neglected and emerging diseases could bring significant global health benefits.
• Governance Innovations: Initiatives like the Coalition for Epidemic Preparedness Innovations (CEPI) helped pivot efforts towards COVID-19 vaccines and could be done the same for other diseases.
• Global Distribution: Lessons learned from COVID-19 vaccine distribution highlight the need for equal allocation systems based on principles of fairness and justice.

Different Types of Vaccines for Treating Emerging Infectious Diseases

The type of vaccines generated is based on its manufacturing materials. The table below mentions the types of vaccines with examples:

Vaccine Types for Emerging Infectious Diseases
Vaccine Type	Examples	Manufacturing Requirements
Live attenuated	Influenza yellow fever Poliomyelitis  COVID-19 RVF (veterinary and human use) Lassa fever chikungunya	Biosafety level 3 manufacturing plant for handling dangerous viruses
Whole inactivated	Influenza Poliomyelitis COVID-19  SARSa Zika RVF (veterinary use)  chikungunya	Biosafety level 3 manufacturing plant for dangerous viruses; needs adjuvant; HPB regimens possible
DNA	SARSa  MERS  Zika  Lassa fever COVID-19
mRNA	COVID-19  Lassa fever disease X	Rapidly adaptable to new emerging viruses; HPB regimens possible; ultracold chain currently impractical for large-scale use in resource-limited settings

Challenges Faced During Vaccine Development

There are various challenges faced during the development of vaccines, some of which are listed below:

• Studies comparing immune responses could replace endpoint trials.
• Finding immune protection clues is tough.
• Trials might not fully show how vaccines benefit whole populations.
• Future trials might focus on vaccine effectiveness and group protection.
• Whether trials will use clinical endpoints or immune responses is uncertain.
• It’s hard to find immune clues, especially with highly effective vaccines.
• Safety and risks like enhanced respiratory disease need careful study.

Strategies to Expedite Vaccine Availability and Distribution

Manufacturing vaccines quickly is challenging due to technical platforms, dosages, schedules, and manufacturer capabilities. Below are the details given to speed up the availability of diseases.

• Vaccine nationalism and bilateral agreements between high-income countries and manufacturers can impact initial vaccine access.
• The Developing Countries Vaccine Manufacturers Network (DCVMN) aims to increase the availability and affordability of vaccines, with its members supplying a large portion of global vaccine needs.
• Technology transfers to DCVMN members have contributed significantly to global health, such as the oral cholera vaccine.
• For COVID-19 vaccines, many companies have licensed production to other manufacturers worldwide.
• Practical aspects like supply, dosing, and storage need optimization for more comprehensive vaccine implementation.
• Some vaccines require ultracold storage because of scalability challenges, while research is ongoing to assess the effectiveness of single doses.

The COVID-19 outbreak teaches us valuable lessons about creating vaccines for new diseases. It highlights the need for close teamwork among health, science, and government experts. While we’ve made various efforts to develop vaccines quickly, we still have work to do to ensure everyone can access them reasonably.

For more information please also check Wikipedia 

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