Many hope that at least one of the Covid-19 vaccine trials underway will prove successful by late fall, blazing a path to developing a vaccine by winter and containment of the virus by next summer. The goal is to conduct mass immunizations of the population, getting enough people protected to prevent community spread of the infection.
While it’s possible that those most at risk—health-care workers, first responders, and nursing-home residents—may receive the vaccine in time to reduce hospitalizations, protect hospitals from being overwhelmed, and avert many deaths by early next year, it’s probably overly optimistic to expect mass immunization in that time frame. While multiple Covid-prevention vaccine trials are planned or already underway, only one of the Covid-targeted vaccines, the so-called Oxford vaccine, has started its final human trial phase (with its first enrollment on May 28).
Two of the trial’s primary goals are protection from infection for six months and no observed serious side effects. The Oxford vaccine investigators estimate that 10,000 participants would be needed to demonstrate that the vaccine works. With the declining amount of virus in the U.K., where the trial was being conducted, they needed to add study sites in Brazil and South Africa, where the disease is more common. Recruitment started in these countries at the end of June.
Even with quick enrollment, it’s easy to see that the evidence required by the Food and Drug Administration for vaccine approval may not be ready until January 2021. A National Institutes of Health trial of the Oxford vaccine, with 30,000 participants, will start in the U.S. in August but will probably not show results until early spring. Other vaccines, including the Moderna RNA vaccine, will not begin recruitment for its final human-trial phase until late July, again pushing possible approval into next year.
Even after a vaccine has been approved, producing it in mass quantities takes time. One potential strategy for speeding up availability is to start production before FDA approval, though private industry is hesitant to take that risk. To this end, the U.S. government, as part of its Operation Warp Speed initiative, along with other national and international nongovernmental organizations, is paying for preapproval mass production of the most promising vaccines, including the Oxford vaccine. The hope is that enough vaccine will be available for mass immunization when approval is granted, but supply-chain problems could arise that would delay that goal.
Even with a ready supply of an approved and effective vaccine, mass vaccination can’t happen without broad popular acceptance. Based on the nation’s experience with annual influenza immunization, this will be a challenge. For the 2018–2019 flu season, vaccination coverage among adults was only 45.3 percent. Considering that only six months of data would exist, at best, for any Covid vaccine by January 2021, it’s likely that uptake will be lower than the influenza number because people will be more cautious about trying the new vaccine. A low uptake, combined with the FDA’s statement that the vaccine needs to protect only 50 percent of those immunized, suggests that only 25 percent of the population may be protected—a level inadequate to stop community spread of Covid. Moreover, this calculation assumes that efforts to immunize people en masse will roll out quickly and efficiently.
It’s reasonable to conclude that we may see continued outbreaks for more than one to two years, despite feverish efforts to develop a vaccine. As such, the U.S. needs to come to terms with a stubborn reality regarding Covid-19: namely, that the virus may persist into the foreseeable future. Given the consequences of many of the mitigation efforts on mental health, unemployment, education, and the economy, America needs to reckon honestly, and apolitically, with what science tells us about the virus—who is getting infected and what we can do to prevent infection, absent a vaccine. We shouldn’t use the hope of a vaccine to delay this discussion. The vaccine will come when it comes.