Today, pnas.org published a news feature by Lynne Peeples, “Avoiding pitfalls in the pursuit of a COVID-19 vaccine“. It is commonly believed that a vaccine will protect people from the deadly complications that are associated with a SARS_COV_2 infection in about 20% of the confirmed cases. In this article, Peeples illuminates some of the reasons that make vaccine development difficult.
The basic idea behind a vaccine is to give someone “a taste” of a pathogen which is strong enough to provoke a strong enough immune response to make antibodies and weak enough not to cause illness. If all goes well, then when the vaccinated person is later infected with the pathogen of interest, then the person’s immune system will recognize the foreign pathogen and eliminate it before it can cause much damage.
Unfortunately, some vaccinated people who later become infected end up having a worse outcome than if they had not been vaccinated in the first place. This “immune backfiring” or “immune enhancement” effect can come about through at least a couple different ways. One is antibody-dependent enhancement (ADE) and another is cell-based enhancement (CBE). Prior vaccines developed for SARS have shown to have this effect and it is unclear if vaccines for COVID19 will also.
Preliminary experimental evidence rejects the hypothesis that ADE is causing any immune enhancement. However, a type of CBE involving T-helper cell (Th2) response was found to be an issue in the development of a SARS vaccine. With the SARS vaccine, the immune enhancement was believed to have been solved by only using a portion of the coronavirus spike protein (that forms the crown/corona sticking up through the bi-lipid membrane).
So, there are universes in which COVID-19 is not a threat to the world. Many of these involve a vaccine that is developed and tested over the next 18 months. Which vaccine it will be, and how immune enhancement will be avoided, will depend on the universe.
Interesting addendum: CNN is now reporting 3003 COVID-19 deaths in the US – an interesting number given the date 03/30, which formatted in European format would be 30/03. I find that a bit synchronistic. It’s also somewhat interesting that 160,698 is factored into only 3 primes, with the two smallest being 2 and 3 ( 2 x 3 x 26783 – 160698).
And, for fun pretending to be diving down a rabbit hole, I just googled images related to 26783 and there is a promoted image for the number. What could “House of Wu” mean? Wuhan? The plot thickens 🙂