In the midst of shelter-in-place orders with no end in sight, many may be ready to end their daily suffering with a jab—that is, a SARS-CoV-2 vaccine.
A group from Oxford University has recently reported promising preliminary results for a vaccine against SARS-CoV-2, the coronavirus that causes COVID-19. The announcement came just three months after Chinese scientists posted the viral genetic code in early January and ignited a vaccine development scramble among about 90 institutions around the world. However, developing a safe and effective vaccine for any disease is enormously expensive, poses multiple challenges, and generally takes years. After more than three decades, we still do not have a vaccine for HIV. Nor has a SARS vaccine ever made it to market.
So, is it really possible to have a SARS-CoV-2 vaccine by the end of the year, as President Trump is predicting?
Outside of the political, economic, and social pressures of a pandemic, research and development of vaccines are prioritized by which diseases pose the greatest threat to global public health. In the case of COVID-19, a spike in hospital cases of pneumonia, a secondary infection resulting from a compromised immune system, tipped off Chinese health workers that something unusual was happening. Those hospital cases were only the tip of the iceberg—an indication that the coronavirus was already spreading in the greater community.
The days of a coordinated federal response to infectious disease threats—à la the polio vaccination campaign spanning the mid-1950s to the early 1960s or even the Obama administration’s efforts to fight Ebola—appear to be gone, at least for now. Instead, current vaccine development is largely the domain of private pharmaceutical companies, which have the resources to keep up to date with the frequent and expensive advancements in biotechnology but are sometimes restricted by motives regarding profit and intellectual property.
The standard FDA approval process for vaccines, as for other pharmaceuticals, requires them to be evaluated in three successive phases of increasingly larger clinical trials, as detailed in the table below. (The FDA process includes a fourth phase of “post-marketing” research that is supposed to take place after the intervention has been approved and is already in use.) Although the first three phases can take many years to complete, not all candidate vaccines succeed in overcoming these hurdles.
While human clinical trials are only conducted after rigorous laboratory and animal testing, participants still face potential risks as well as benefits. If ethical issues or health complications arise in any phase of the research, trials are stopped. The National Vaccine Injury Compensation Program (VICP) pays damages to individuals in the rare cases in which they can document that they have experienced serious adverse reactions.
For example, a person vaccinated with an ineffective product could put themselves in high-risk situations, believing they were protected from the virus. After being exposed to and acquiring the novel coronavirus, they could get sick with COVID-19 themselves or become an asymptomatic carrier of the disease, spreading the virus to immunocompromised populations such as the elderly and pregnant women and prolonging the pandemic. An unsafe vaccine, on the other hand, might have negative effects that could go undetected for years.
As much as we might be tempted to speed up SARS-CoV-2 vaccine development, cutting corners on the FDA approval process can pose devastating consequences. We need to temper our desperation to get everyone back to work and be able to see our loved ones with the understanding that moving forward requires sufficient caution to ensure that vaccine candidates are thoroughly vetted and demonstrate safety and efficacy.
Even after a safe and effective vaccine is approved, the logistics and ethics of production and distribution could delay widespread access by years. Scaling up vaccine manufacturingfor the billions of doses that will be needed to inoculate the world’s population would require enormous global cooperation and goodwill, which currently seem in short supply. Moreover, decision makers would have to balance tradeoffs between switching production capabilities to a SARS-CoV-2 vaccine and staying with regular vaccine production. A nationwide vaccination campaign would call for thousands of licensed, qualified health professionals to inoculate recipients safely.
Even if a SARS-CoV-2 vaccine isn’t possible within this year or the next five, beginning the vaccine development process and readying production facilities will be helpful if coronavirus becomes seasonal or if immunity—whether vaccine-induced or by exposure to the virus—isn’t long-lasting. Ensuring that the first version of the vaccine is safe and effective not only fights transmission rates, but also builds the foundation for future, better iterations to be trusted and widely used.
Although some world leaders are optimistic that a SARS-CoV-2 vaccine is right around the corner, there is no guarantee that such hope is founded. We need to acknowledge that the vaccine development process takes a long time to ensure the safety and efficacy of vaccines, since releasing a poor vaccine could be more deleterious to human health than the continuation of lockdown measures. Right now, our best inoculation is making sure we all take precautions to stay indoors and stay safe.
With editing by David Tuller, DrPH.
Also see COVID-19: What the Numbers Mean.