A Coronavirus/Covid-19 vaccine could take three years to make. I spoke with a high-ranking vaccine expert at a global pharmaceutical company who walked me through the challenge. Below, I summarize my discussion with them. 1/

Let’s start with other crises, and how the effort to create a vaccine went. First, Ebola. The Ebola epidemic in West Africa happened in 2014-16, after multiple localized outbreaks in prior years prompted research on the virus. 2/

Even with this head start, vaccine was not available for clinical testing until 2016, and it was only licensed in 2019/2020 — a good five years later. Pre-licensure use of the vaccine (meaning, before the vaccine is officially approved) did stop the recent Congo epidemic. 3/

Compared to Ebola, SARS-CoV-2 (aka Covid-19, or colloquially “the Coronavirus”) has caused more damage to powerful countries, and because it is a respiratory virus it has become a pandemic. 4/

On one hand, because it has infected so many powerful countries, there is a strong sense of urgency from those countries to do something about it. On the other, the amount of vaccine needed to impact this epidemic is staggering, especially if it requires more than one dose. 5/

For example, the Prevnar 13 pneumonia vaccine for infants is 4 doses. If you get a pneumonia vaccine at age 65, you’ll get 2 doses. The newest HPV vaccine requires 3 doses. So the number of doses utlimately needed maybe be multiple times the # of people needing vaccination. 6/

Moreover, vaccines for respiratory RNA viruses are particularly tricky because some candidates have made the disease worse (e.g., RSV), and others have lower than ideal efficacy due to antigenic drift (i.e., the virus mutates, so the previous vaccine provides less immunity). 7/

Also, the target population (the elderly) doesn’t have a great immune system. Vaccines tend to work less well on the elderly, so protecting that population as a whole will require herd immunity, i.e., making a significant # of them immune to the virus at the same time. 8/

Hence the need for massive amounts of vaccine, because seniors may either need multiple vaccinations, or larger individual doses. Seniors get a stronger dose of the flu vaccine that contains 4 times the normal amount of antigen. Thus, even more antigen needs to be produced. 9/

There are major gaps in knowledge that challenge vaccine development:

Do people who recover from Covid-19 develop immunity?
If so, what is the nature of the immunity & how long does it last?
Do people who recover continue to shed virus? If so, why aren’t they sick? 10/

What is the immune response that is needed to stop or attenuate the disease?
Will the virus mutate like flu, requiring annual vaccination and a new vaccine be created every year? 11/

The vaccine expert believes that the companies that have chosen to create big splashes around their vaccine programs are irresponsible and unrealistic. Even with the most intensive approach, the studies can be done in two years. 12/

This assumes we have a general correlate of protection, a way of measuring that someone is now immune – i.e., being able to measure anti-Covid-19 antibodies and showing that these antibodies are protective). But scale up of manufacture will take a longer time. 13/

The vaccine expert tells me that the most likely date for availability of vaccine for frontline workers is three years at the earliest. And that's a lot longer than anyone has been claiming. https://americablog.com/2020/04/coronavirus-covid-19-vaccine-could-take-3-years-to-make.html 14/