Chapter 137
Defeating Infectious Agents — 1
In the early months of the COVID-19 pandemic, we faced an existential crisis. How quickly we tend to forget the catastrophes of mass deaths, overwhelmed hospitals without enough ventilators that were inundated with very sick patients lying on gurneys in hallways or in their cars in the parking lots. Especially among people in the second half of their lives, who were in fact at high risk, there was a pervasive sense of fear and doom.
By April 1, 2020, just a few months after the threat was recognized, a forecast was made that we might have a COVID vaccine (against SARS-CoV-2) within eighteen months. Ridiculous! No vaccine program had ever come close to such a short time frame! The average time from identification of the causal infectious agent to a licensed, commercially available vaccine is eight to ten years, and that’s for the ones that were proven safe and effective. Even for mumps, the fastest developed vaccine in history, it took four years. As you can see from the graph below (fig. 10.1), some vaccine programs took over one hundred years, and many, like tuberculosis or human immunodeficiency virus (HIV), are still being worked on. In the year prior to COVID’s emergence, Anthony Fauci and colleagues wrote: “In total, 15 to 20 years would be a typical timeframe from virus discovery to vaccine availability if the process proceeds smoothly and there are no major biological or logistical challenges.” A realistic projection for a COVID vaccine from several experts was November 2033. That’s 2033. A more optimistic note, based on the average of all FDA-approved vaccines between 2010 and 2020, was 8.1 years of clinical development.
Figure 10.1. Time lag from pathogen identity to developing a successful vaccine, including many without a vaccine (no date at right). Adapted from International Monetary Fund, Communications Department, “Picture this: The journey of the Covid-19 vaccine,” Finance & Development 58, no. 4 (December 2021): A012, https://doi.org/10.5089/9781513595894.022.A012; and Samantha Vanderslott et al., “Vaccination,” Our World in Data, accessed September 5, 2024, https://ourworldindata.org/vaccination.
It took ten months.
So, what can we learn from the extraordinary success of COVID vaccine programs? It wasn’t just getting vaccines with the acceptable threshold of 50 percent efficacy for protection against infections—these came in at 94 to 95 percent reduction. Not surprisingly, multiple factors paved the way. First, the achievement was preceded by more than three decades of work developing mRNA for vaccines. Since messenger RNA codes for proteins, using our body as its own vaccine-production factory was theoretically an attractive alternative. It is a much slower and complex project if the vaccine is made of proteins rather than mRNA, or an attenuated virus that simulates the immune response of having an infection without actually getting one. The hope was that mRNA vaccines would eliminate complicated cell-based production methods, avoid integration with our genome (as could occur with a DNA vaccine), and be less likely to be met with an individual’s preexisting antibodies. The scalability for mRNA is huge: a five-liter bioreactor on a lab bench can make nearly a million doses of vaccines!