All hopes are pinned these days on the approval of a coronavirus vaccine. But exactly how long is it likely to take to get a vaccine and, once we do get one, will it be effective? According to the World Health Organization, there are now 140 vaccine candidates in pre-clinical stage and 23 under clinical evaluation. The chart below from Morningstar outlines the leading candidates, when they are expected to enter final trials and their anticipated approval dates. The recent outbreaks here in the U.S. may actually speed up the approval process by increasing the pool of trial candidates likely to be exposed to the virus.
AstraZeneca’s combined effort with Oxford University is leading the pack with a 30,000 patient, phase 3 trial slated to start next month. Trials for vaccines from Johnson and Johnson, Moderna and Pfizer/BioNTech are also expected in the next few months. Morningstar estimates that given the progress to date, the three leading candidates could receive Emergency Use Authorization by January of 2021. This FDA approval requires a lower level of evidence that the drug in question is effective and is issued during declared states of emergency. If these approvals are forthcoming, they will represent the fastest vaccine development in modern history. To date, the fastest start to end process took four years when a mumps vaccine was approved in 1967.
The success to date and sheer financial investment, estimated to exceed $10 billion in the U.S. alone, give good reason for optimism. But we are far from the finish line in this effort. On the science front, any treatment needs to be both effective (reduces transmission rates by at least 50%) and safe. Drug trials to prove both are a slow and tedious process. The degree of protection or “efficacy” of any vaccine also remains uncertain. Will an approved vaccine produce lifelong or temporary immunity? Answering this question will require a better understanding how quickly the virus mutates.
Manufacturing will also be challenging. Herd immunity occurs when enough members of a population, typically 60%-90%, are immune to the virus either because they have contracted it or been vaccinated. Meeting this goal globally will require producing billions of doses. Supply chains must be built for everything from vials to syringes. International cooperation to pool resources and smooth out bottlenecks could make a big difference in how smoothly and quickly this process goes.
Given the issues outlined above, it is reasonable to assume that early supply levels will fall far short of demand. While most agree that healthcare workers and high-risk populations (the elderly and those with health issues) should be first in line, decisions regarding who gets which vaccine and when will likely be contentious. Governments from across the developed world are already locking in supply through upfront funding of leading candidates. Finally, will sufficient people take the drug to drive down transmission rates? Obstacles to vaccine adoption today include not just individuals generally opposed to vaccines but those concerned about safety issues given the historic speed of development.
Given these challenges, it is unlikely that any vaccine or series of vaccines will be the “magic bullet” many hope. Lots of things still need to go right on the science front and scaling up sufficient levels of manufacturing and distribution is going to take time. But the good news is that vaccines are only one of the means we have of eventually eliminating this scourge. Other forms of treatment and prevention will be equally important. On the treatment front, Gilead’s remdesivir combined with other repurposed immunology drugs is showing good outcomes and increasingly available. A range of new targeted antibody medications also offer hope. After six months of fighting this disease, healthcare workers are now armed too with an improved and hard won understanding of what constitutes effective treatment. Finally, continued adoption of behavioral changes such as hand washing, mask wearing and yes, social distancing will continue to play a key role.