Research roadmap for coronavirus vaccine development

Download 202402 Draft Coronavirus Vaccine research roadmap Final

DNA/RNA vaccines

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Dependencies

9 Adjuvant

Next steps

1 Vaccine

DNA/RNA vaccines

Research Question

Develop nucleic acid-based vaccines that are efficacious, safe and
usable in animal production systems, whilst establishing cost effective
mechanisms for product delivery

Research Gaps and Challenges

Mucosal immunity: DNA/RNA vaccines typically induce systemic
immunity, but their ability to generate strong mucosal immunity
remains limited. This is critical for respiratory and gastrointestinal
coronaviruses in animals
Cold chain maintenance: Currently mRNA vaccines, in particular,
require stringent cold chain conditions, which complicates distribution
in remote or field conditions, especially problematic for livestock and
wildlife
Affordability: Despite their high efficacy, RNA and DNA vaccines may
be more expensive to produce and distribute, particularly in lowincome regions or for large-scale animal vaccination campaigns, as has been seen for COVID-19 access at a global level.
Sterilizing immunity: Related to the mucosal immunity, there is
uncertainty over whether these vaccines can induce sterilizing
immunity. Will non-sterilizing immunity will be enough to control viral transmission in large herd/flocks etc?
Breadth of immunity: mRNA vaccines tend to be species-specific,
raising questions about their ability to protect across different animal
species
Response to variants: While DNA and RNA vaccines can be quickly
updated to target new variants, it remains a challenge to predict how
new variants will emerge and escape immune responses, although this
is true of all vaccines
Public perception: Public opinion on the safety and efficacy of novel
vaccine platforms (DNA/RNA) remains mixed, especially in agriculture, where concerns about the safety of animal products from vaccinated animals can affect acceptance

Solution Routes

Non-sterilizing immunity: Research should investigate how non-sterilizing immunity driven by DNA/RNA vaccines could impact immune selection and recombination of viral variants, as well as its role in disease control
Alternative administration routes: Investigating alternative routes of
administration, such as aerosolized RNA vaccines, may enhance
mucosal immunity and provide better protection at the sites of viral
entry
Broadening immunity: DNA vaccines may offer broader immunity
across species. Studies should explore how these and mRNA vaccines
can be utilized in different hosts to create cross-protective immunity
Vaccine-therapeutic combinations: Testing the combination of
vaccines with therapeutic agents (e.g., antiviral drugs or immunomodulators) could improve outcomes by enhancing immune
responses and viral clearance
Antigen selection for mRNA vaccines: Research is needed to
determine the best combinations of antigens (e.g., spike, nucleocapsid)
to include in DNA/RNA vaccines, aiming to elicit a balanced T-cell and
antibody response
Investigating immune tolerance: The increasing IgG4 levels observed
with multiple mRNA doses suggests the possibility of immunotolerance, which should be further investigated to ensure long-term efficacy of these vaccines
T-cell responses: Studies are required to assess how DNA/RNA vaccines induce long-lasting T-cell responses, which are critical for durable protection and viral clearance
Maternal immunity: The role of maternal immunity should be explored in developing vaccination plans for production systems with animals of different ages, particularly in livestock where passive immunity from mother to offspring is important
Public education campaigns: To address concerns around DNA/RNA
vaccines, educational campaigns should focus on the safety and
efficacy of these platforms, particularly in the context of safe animal
products entering the food chain

Dependencies

Vaccine administration strategies: A comprehensive vaccine
administration plan must account for vaccine durability, animal age,
and the type of production system to optimize outcomes across
species
Public communication plans: Clear communication strategies are
needed to improve public acceptability of products from vaccinated
animals, addressing concerns about safety and marketability
Emergency financing and commitment: Investments are required to
ensure vaccines are produced and available for immediate use during
variant emergencies, with commitments from governments and
organizations to purchase vaccines in the event of outbreaks in
affected animals
Regulatory acceleration: Regulatory pathways need to be streamlined
to allow for the rapid approval and deployment of new vaccines in the
event of emerging variants, similar to what was done during the
COVID-19 pandemic

State Of the Art

mRNA vaccines: mRNA vaccines have demonstrated efficacy in humans (e.g., COVID-19) but are generally species-specific, which raises challenges in developing cross-species vaccines for animals. However, the speed of R&D during the COVID-19 pandemic showed that these platforms could be rapidly adapted in emergencies
T-cell responses: The majority of studies on DNA/RNA vaccines have
shown relatively low T-cell responses, which may limit their ability to
provide long-term protection without further optimization
Immune tolerance: There is emerging evidence that repeated mRNA
vaccinations increase IgG4 levels, suggesting the possibility of immune
tolerance, which could reduce vaccine effectiveness over time. This
phenomenon warrants further study