Interview
This vaccine could stop the next pandemic | The Economist
- Universal coronavirus vaccines could have saved millions of lives and maintained societal stability at the start of the pandemic, serving as a bridge before highly specific vaccines were developed.
- The human immune system consists of two primary components:
- The innate immune system, a fast-acting, "first defense" mechanism that uses cells like macrophages to immediately detect and engulf pathogens, and signals for reinforcements if the threat is large.
- The adaptive immune system, a slower response (taking days to mount) that relies on specialized B and T cells with specific receptors to identify and neutralize particular antigens.
- Standard vaccines introduce harmless antigens to the body to trigger the adaptive immune system, which then creates "memory cells" (B and T cells) to enable a faster, targeted response upon future exposure to the same pathogen.
- Recent research over the past 15 years has overturned the view that the innate immune system is merely a basic defense, revealing it can be "trained" to provide broad immunity against diverse diseases.
- Evidence for this includes the BCG vaccine (against tuberculosis), which researchers found to alter the innate immune system's ability to fight a host of other diseases.
- Other vaccines, including Shingrix (shingles), Measles, and Polio, also appear to induce this non-specific protective effect.
- Scientists, such as Mihaly Netea at Radboud University, have identified that the BCG vaccine induces epigenetic changes in innate immune cells (myeloid cells):
- These changes act like "bookmarks" on the genome, influencing gene transcription to keep cells in a state of high alert.
- This "training" keeps innate cells activated longer and more aggressively patrolling, ready to tackle future infections without prior specific exposure.
- A 2024 study by researchers at Stanford University attempted to recreate these BCG-like effects using a targeted system in mice:
- The study successfully trained innate immune cells in the lungs to remain hypervigilant against viruses, bacteria, and allergens.
- However, the findings are limited by the differences between mouse and human biology, including genetic diversity and the fact that humans are exposed to a wider range of pathogens than lab mice.
- Future visions for broad-spectrum vaccines do not anticipate a single shot protecting against all pathogens, but rather a complementary strategy:
- Broad vaccines would be administered alongside specific vaccines (e.g., for a specific flu strain or coronavirus variant).
- The trade-off is that broader coverage may offer less depth of protection against individual variants compared to highly specific vaccines.
- Proposed deployment scenarios include administering universal vaccines prior to anticipated bad flu seasons or at the onset of new pandemics to buy time until strain-specific vaccines are developed.