Why does the weakness of low durability dog newer vaccines?

Why does the weakness of low durability dog newer vaccines?

Subject: IR

Section: Places in news

Context:

• The measles vaccine is highly effective, often providing lifelong protection against the disease, which is not common among most vaccines.

Details:

• A review of 34 licensed vaccines revealed that only five offer protection for over 20 years, and just three, including the measles vaccine, provide lifelong immunity.
• Fifteen of these vaccines offer 5-20 years of protection, while the remaining ones have a much shorter efficacy, typically around five years or less.
• Notably, the majority of new-generation vaccines tend to have a shorter duration of protection.

Different immune response:

• The process of developing immunity after vaccination is intricate and involves the generation of memory B cells by our lymph nodes, which remember the antigens introduced by vaccines and produce potent antibodies when encountering these antigens again.
• These memory B cells require T cell support to be produced, and not all vaccines stimulate this necessary response.
• Some vaccines, such as those for typhoid and pneumococcal diseases, do not prompt the body to create B cells, leading to the need for frequent boosters to maintain immunity.
• The presence of memory B cells alone does not guarantee immunity; for some vaccines, like those for measles and rubella, the level of these cells remains consistent over decades, correlating with long-term antibody levels.
• However, this is not true for all vaccines, indicating that another mechanism, involving long-lasting plasma cells (LLPCs) that reside in the bone marrow and can last for decades, plays a crucial role in sustained immunity.
• Achieving long-term protection involves generating both memory B cells and LLPCs, with differences in vaccine efficacy largely due to their varying abilities to produce these cells.

Explaining the disparity in durability:

• The durability of vaccine-induced protection is influenced by three primary factors: vaccine-related, target pathogen-related, and host-related elements.

1. Vaccine-related factors: Live viral vaccines (e.g., measles, rubella, yellow fever) and virus-like particle (VLP) platforms (e.g., HPV vaccines) generally offer longer-lasting protection compared to killed pathogen or subunit vaccines. The timing between doses, such as a six-month interval for hepatitis B vaccines, and the use of adjuvants, like TLR agonists, are crucial for a robust and lasting immune response.
2. Target pathogen-related factors: The characteristics of the pathogen, including its incubation period and genetic stability, significantly impact immunity duration. For instance, viruses with shorter incubation periods (like influenza and SARS-CoV-2) offer limited time for an effective immune response, leading to shorter immunity periods. Conversely, pathogens with longer incubation times or those causing more prolonged infections tend to result in more durable immunity. The genetic stability of the virus also plays a role; RNA viruses with high mutation rates, such as influenza and SARS-CoV-2, require frequent vaccine updates.
3. Host-related factors: The age and gender of the individual, along with other physiological factors like obesity, can influence the persistence of vaccine-induced antibodies. Even the time of day the vaccine is administered affects immune response, with morning vaccinations proving more effective due to the circadian clock’s impact on immune functions.

• Advances in bioengineering are introducing new strategies to enhance vaccine durability, such as nanoparticle and VLP technologies, controlled antigen delivery, and targeted adjuvant activation. These innovations aim to develop vaccines that provide long-lasting protection with fewer doses by better understanding and leveraging the mechanisms of immune response durability.