FACULTY Q&A

ANN ARBOR–In late April, the federal government announced Operation Warp Speed, an aggressive COVID-19 vaccine development program that aims to have at least 300 million doses of vaccine available in the United States by January. Jason Pogue, clinical professor of pharmacy, discusses the feasibility of this aggressive timetable.

Is this timeframe possible?

It is impossible to say if it is possible, because there are too many unknowns. This is a first: No vaccine development has approached this rapid of a timeline–however, never have we seen a program afforded this many resources. While I am skeptical of the timeline, I remain hopeful and somewhat optimistic that we can have some amount of vaccine at some point in 2021 in the United States. Then, decisions on prioritizing who is vaccinated (high-risk populations, essential workers, disease epicenters) and potential global collaboration/cooperation with vaccines in development abroad will be critical.

What are some of the unknowns?

First and foremost, we do not know if the handful of leads that the U.S. will focus on will be safe and effective. Clinical trials are essential to determine the safety and efficacy, and even though the plan is to perform them in a faster timeline, everything depends on whether the vaccine works.

I also think there will be some unique challenges in determining the efficacy of a vaccine during a pandemic, particularly with so many unknowns about the causative pathogen. For example, to show that a vaccine works you must demonstrate that significantly fewer patients taking the vaccine become infected with SARS CoV-2, compared to controls. However, if these studies don’t occur until summer or fall, unknowns about the seasonality of the virus could impact the number of patients who get infected.

Furthermore, the control arm infection rate will largely be determined by the trajectory of COVID-19 months from now, and we do not know that. Additionally, we’ve learned that patients can be asymptomatically infected, and studies must capture this. Also, you’d need to control for social distancing, the density of infections in the patients’ region, mask use, and other factors that may change during the study, and influence the infection rate. These add complexities to the rapid timeline.

Additionally, it’s unknown how quickly the ramp-up phase would proceed, and it’s possible that the most successful manufacturers have the least effective vaccine. So, we could have different amounts of different vaccines with different degrees of protection. A coordinated distribution will be critical.

Won’t the U.S. face the same supply chain problems that have plagued the implementation of widespread testing?

I am not clear what supplies are needed for vaccine development and the relative abundance of each of them. However, with global efforts being made at vaccine development, it’s reasonable to believe that supply chain problems could arise.

How effective does a vaccine need to be to promote herd immunity and stop spread?

The better question is, “What percent of the population must have immunity for an infection to die out?” This is called herd immunity, and many variables contribute to it. Some of those variables include the percent of the population that’s immune (either via vaccine or through natural infection), and how infectious the pathogen is (which can be modified based on social distancing and other preventative measures.)

In my opinion, we’ll be dealing with COVID-19 to some degree for the foreseeable future. There are many unknowns, including the degree/duration of protection antibodies and cellular immunity provide.

With that said, even a suboptimal vaccine can benefit the population. The annual efficacy of the seasonal flu vaccine is usually 40% to 50%, and many experts consider it a poor vaccine. However, it prevents millions of influenza cases annually and can also decrease the illness’ severity in those who become infected.