Why does it take so long to develop a (COVID-19) vaccine?

With persistently conflicting messaging, it is difficult to understand how some estimates of COVID-19 vaccine readiness promise a vaccine by the end of the year, and others like Dr. Anthony Fauci has repeatedly cautioned us that a safe and effective vaccine, in the most optimistic of scenarios, will take 12 – 18 months.  Why the disparity and why so long? 

For perspective, it helps to know our track record of vaccine development.  The fastest we’ve previously developed a vaccine was for mumps, and it took 4 years.  Overall, it has taken 10 to 15 years to develop a vaccine — so 12 to 18 months would itself be a record-breaking achievement.   Are we skipping phases this time, or just racing through them?

The answer is a combination of factors, including urgent global need, the magnitude of resources being devoted internationally enabling clinical trials to simultaneously conduct multiple phases, the scientific advancements learned from developing a vaccine for the original SARS-CoV-1virus leading to the unprecedented strategy of nucleotide based vaccines.  All of this combined with preparation of multiple manufacturing sites to allow rapid upscaling of production once a vaccine is developed.  

To learn more, watch this excellent video by Dr. Seema Yasmin produced by Wired.

Vaccine Update

A preprint study (not yet peer reviewed) of the vaccine being developed by Oxford University and AstraZeneca released May 13th showed that vaccinated macaques were protected from COVID pneumonia.    

Moderna (Cambridge,MA) last week announced completion of phase 1 of its human coronavirus vaccine trial.  It had only 8 subjects but demonstrated acceptable safety data to move on to phase 2 trials.  They added that all 8 subjects developed neutralizing antibodies which should protect against severe COVID disease.

China’s vaccine candidate, which uses an adenovirus vector to deliver the vaccine’s genetic material, has also completed phase 1, with safety data published in The Lancet May 22nd.  Subjects all had rapid binding antibody and neutralizing antibody responses following vaccination.  However, they observed that subjects with preexisting antibodies to the adenovirus used in the vaccine had lower immune responses.

Novavax this week announced it had begun clinical trials in Australia.  Novavax was an early frontrunner among smaller biotechs, receiving $388M from Gates-backed CEPI.  It too has an aggressive timeline, but is also leveraging global manufacturing partners in China and India, scientific partnerships with the Serum Institute and Oxford University to be able to produce any one of dozens of vaccine candidates in the works worldwide, including in their new plant in the Czech Republic which they say will be capable of 100 million vaccine doses per month by January 2021.