Doug Douville: A reality check on the coronavirus vaccine
Early in the pandemic, I, like most Americans, thought that once we had a vaccine, this scourge would quickly go away. Though there is still much we don’t know and can’t predict, the reality is that the defeat of COVID-19 using a vaccine is many months and many more lives lost away. So why is that and what can we do in the interim?
There are two ways to end a pandemic. The first involves the aggressive use of so-called social tools. These include hand-washing, mask-wearing and social distancing. Many countries, such as South Korea, New Zealand and Vietnam, have combined these with effective testing and aggressive contact tracing to stop the pandemic in its tracks.
Obviously, here in the U.S., we have failed in the use of these measures. This leaves us with option No. 2, using scientific tools. These include effective therapeutics and an effective vaccine. So far there is no highly effective treatment. The best we have is dexamethasone. While its 30% reduction in mortality in the sickest patients is an important advance, it is not a needed game changer.
That leaves us with a vaccine. An effective vaccine will certainly change the course of the pandemic. Yet the public’s expectation of how quickly this will happen is unrealistic.
A little epidemiology can explain why. When a certain percentage of the population becomes immune to an infectious agent, either by infection or immunization, that agent will cease being transmitted. This is called herd immunity. Some have called for achieving herd immunity rapidly by allowing the virus to run through the population unimpeded — all the while protecting the most vulnerable.
It is extremely difficult to protect, or even determine, the vulnerable. And many people with sublethal infections may suffer long-term disabilities. Achieving herd immunity by natural infection in the U.S. could kill up to 2 million people. Most Americans would prefer that we achieve herd immunity with a vaccine.
So why will it take many months to get enough Americans vaccinated to achieve herd immunity? Final studies still need to be completed. Delays have already occurred with two promising vaccines. Production has already started on several vaccines, but most vaccines require two doses and the numbers are staggering.
If our COVID-19 testing debacle is an indicator, the final steps, distribution and administration of vaccines will likely be chaotic, requiring many more months.
While all of the above problems are surmountable, another problem may not be. Assuming roughly 10% of Americans are already immune, herd immunity will require anywhere from 40% to 60% of Americans be immunized. Given the many variables and unknowns, this is a very gross estimate. The effectiveness of the vaccine will dictate what number is required. The less effective the vaccine, the larger the number of people who will need to be vaccinated to achieve herd immunity.
Some vaccines provide complete protection, e.g., the polio vaccine, while others provide limited protection, e.g., the flu vaccine. The vaccines being tested will likely provide limited protection. Herein lies the potentially insurmountable obstacle. If only half of Americans are willing to get vaccinated, only a vaccine providing complete protection will achieve herd immunity. It’s unlikely we’ll have this.
There is a cynical adage among physicians that all bleeding eventually stops. In the same vein, eventually we will achieve herd immunity — but when and at what cost. We can hope that we’ll have a completely protective vaccine. We can also hope for a therapeutic breakthrough.
Sadly, hopeful thinking has gotten us to where we are now. Three things need to happen immediately or we’ll experience an even greater cataclysm in the months to come. First, we need to redouble our use of social tools, testing and contact tracing. Second, we need an aggressive national campaign to persuade people to get vaccinated. Last, our leadership and citizens need to understand the limitations of a vaccine so they can focus on what works now.
The current president is either unable or unwilling to do these things. An educated public can force leadership to follow the science or elect leaders who will.
Doug Douville, M.D., is a family physician currently working at a charity clinic. He was an Air Force physician for 20 years and was in private practice in West Valley City for 15 years.
from The Salt Lake Tribune https://ift.tt/2IeZcXH
No comments