Science / Epidemics
Walking slowly towards the outgoing tide
Why COVID-19 vaccines are both better than we could ever imagine and the wrong strategy to end the pandemic.
There’s a great deep dive in this past weekend’s New York Times about the decades-long journey that brought mRNA vaccines from concept to cure. It’s the kind of story that I love (and that my book Invisible Siege: The Rise of Coronaviruses and the Search for a Cure, chronicles extensively): a story about scientists working towards turning an esoteric dream into a reality, even (especially!) when nobody else cared. And what a reality: the COVID-19 vaccines developed by Pfizer and Moderna have now been injected into billions of arms and blanketed the world with some pretty serious protection to disease. That’s something that we take for granted, but it’s worth stopping, breathing deeply, and taking some perspective for a minute on what that really means.
While the Omicron wave has made everyone feel miserable, the scientific response to the pandemic has played out far better than anyone dared dream. It starts with those mRNA vaccines. For context, the US Food and Drug Administration (which has final say on whether a drug can be marketed in the US) set the threshold for COVID-19 vaccine effectiveness at 50%. Let that sink in. Fifty percent! That means, of course, that getting a vaccine would be a coin toss: half the people who got a shot would still get as sick as the people who didn’t. The rationale for the FDA was that this was the absolute minimum level of effectiveness to get a population to herd immunity (which is about 70% of a population that is immune to getting sick) through a combination of naturally-acquired immunity (by getting infected with the SARS-CoV-2 virus) and a kick ass inoculation campaign that managed to get close to 100% of the population vaccinated. The upshot is that each percentile increase in the effectiveness of a vaccine makes it that much easier to reach herd immunity and get through the pandemic.
The vaccines stay the same, but the virus keeps on getting smarter…
When Pfizer and Moderna shared the results from their mRNA vaccine trials, both were, stunningly, 95% effective against illness. What a relief: it meant that reaching that 70% herd immunity threshold would be way easier (read: would require getting fewer people vaccinated) than if the vaccines were 50% effective. What’s so damn frustrating, though, is that while humanity has been getting itself immune to COVID-19, the SARS-CoV-2 virus hasn’t been standing still. At this point, the vaccines are by and large made to stop the spread of a version of the virus that first spread through Wuhan, China. Since then, three major variants have spread. D614G, the first, was the version of the virus that first went global, replacing the ‘wild-type’ version of the virus that first emerged in Wuhan. Delta was the variant that ultimately outcompeted D614G (with honorable mentions to Alpha, Beta, and Gamma), and Omicron has now shown itself to be far more transmissible than anything that has come before. Each step of the way, the vaccines have seen their effectiveness degrade, and the rapid spread of Omicron (and its accompanying hospitalizations) proof of just howwily coronaviruses are in evolving to overcome our defenses.
This matters because, as we’re seeing now, vaccines will become less effective over time, necessitating boosters and updated formulations to match the most recent variant. As long as herd immunity is elusive, new variants will inevitably arise, spread, and weaken vaccines.
Vaccines and the end of the pandemic
That brings us to a darker truth that rarely gets coverage: variants are going to keep showing up as long as the world—not a single country, but the entire world—doesn’t have access to vaccines. It’s not enough to protect people in wealthy countries. That might keep us in a sort-of mid-pandemic limbo, with breaks between waves followed by escalating case numbers and deaths, and lockdowns and restrictions, the whole thing continuing ad nauseum. But hoarding vaccines is only going to treat symptoms of the pandemic. If we’re serious about ending the threat of COVID-19, everybody everywhere needs access to a vaccine. That way, herd immunity can be reached across the world, which would then stop the virus from being able to replicate and mutate at will, which would reduce the chances of horrible new variants emerging, which would end the pandemic once and for all.
It’s a simple formula and one of the rare moments when the ethical path (vaccines for everyone) fully lines up with the most selfish one (I want the pandemic to end for me).
While the dream of vaccine equity has a ways to go, there are some really hopeful signs that we might just get there. The mRNA vaccines weren’t designed to be especially cheap or easy to transport globally. But new vaccine candidates like Corbevax (dubbed ‘The World’s COVID-19 Vaccine’) and HexaPro are specifically being developed as inexpensive, easily distributable options for global scale-up. Let’s hope they get there.
Until they do, worry not (there’s already enough anxiety out there). Vaccines are still an incredibly effective way to protect yourself. They just aren’t likely to end the pandemic. In my next newsletter, I’ll tell you about the secret weapon that 19 might just make COVID-19 the last coronavirus pandemic to wreak havoc on humanity. Hint: it doesn’t have anything to do with vaccines…
Meanwhile, in Dan Werb news:
Publishers Weekly named The Invisible Siege: The Rise of Coronaviruses and the Search for a Cure one of the top ten science books of the upcoming season. In their starred review, they called it “a page-turning and unsettling look at the history of coronaviruses”, and that “the light he sheds on scientists whose work has gone largely under the radar makes for a moving account.” Well, damn. That’s nice. You can pre-order the book here.
Thanks for reading. You can find me at my website and on Twitter. If you want to go deep on my science, check out my one true love: Pubmed.