Another way researchers are attempting to accelerate vaccine development is by repurposing drugs. In a recent paper published in Nature, researchers used an open-access drug library to identify 21 different drugs that can inhibit replication of the SARS-CoV-2 virus in mammalian cell-based assays in a dose-response manner.⁸

One way to increase the odds of winning the vaccine lottery is by testing myriad potential vaccines at the same time across the globe rather than putting all efforts into just one. At the time of this writing, there are 49 different SARS-CoV-2 vaccines in various clinical trial phases, according to the London School of Hygiene & Tropical Medicine’s VaC COVID-19 vaccine tracker. Ten of those candidate vaccines are in Phase III clinical trials. Additionally, there are currently 199 vaccine candidates in the preclinical phase.

The WHO Solidarity vaccine trial is a global effort that is testing multiple vaccines in geographically diverse regions with high incidence and attack rates of COVID-19 through fixed and mobile research sites. Researchers estimate that a vaccine that halves risk should show efficacy within three to six months of a trial in these highly endemic areas.

Vaccine Types for COVID-19

Let’s look at the landscape of the potential vaccines being investigated. The main categories of candidate vaccines include nucleic-acid vaccines (DNA versus RNA vaccines), nonreplicating viral vectors vaccines, virus vaccines (live attenuated viruses versus inactivated viruses), and protein-based vaccines (subunit vaccines with antigenic fragments).¹¹ Table 1 shows the advantages and disadvantages of each of these categories.

Table 1: Overview of Candidate COVID-19 Vaccine Categories

*How quickly the vaccine can become available under emergency conditions.
Adapted from Calina et al and Jeyanathan et al.

Briefly, the 10 candidate vaccines in Phase III clinical trials include two nucleic-acid vaccines (mRNA), four viral vector vaccines (adenovirus-based), one protein-based (recombinant coronavirus proteins plus an adjuvant), and four virus vaccines (three inactivated virus, one live attenuated virus). The one live attenuated virus vaccine in a Phase III clinical trial is using the old Bacillus Calmette-Guérin vaccine.

Who Should Get the Vaccine First

A few major organizations, such as the WHO and the US National Academies of Sciences, Engineering, and Medicine, recommend prioritizing health care workers and those with frontline jobs.¹² Of course, when the vast majority of health care workers in the United States are white, this promotes structural health disparities by depriving those who have been disproportionately impacted by the virus of a potentially effective vaccine.¹³ Expanding this to all workers in health care facilities would be a step in the right direction.

What to Do Until a Vaccine Is FDA Approved

Face masks, social distancing, hand washing, large crowd avoidance, and personal protective equipment are the non-vaccine vaccines. They work, and they are easy to do. Until we have a safe, effective, and available vaccine, don’t let your guard down.