(CNN) What happens if a coronavirus vaccine is never developed? It has happened before.

This is possible.  Before we get into it, urgency requires this up front:

Vaccines come in different quality grades. The quality depends on two main factors: the antigenic target, and the process by which the vaccine is made. For example, leafy green plants like tobacco can be used to make vaccines.  But a vaccine manufactured in  tobacco plants  cannot reach the  quality of a well designed animal-cell culture vaccine. It could still be good enough.

• The ASAP is for a vaccine with some benefit in the shortest possible time.
• A mediocre, but not harmful, vaccine satisfies this immediate requirement better than a high quality vaccine on the standard development time scale.
• Messenger RNA, used by Moderna and a few others, is a new addition to vaccine manufacture. The big advantage of RNA is that it can be produced by purely chemical means from a DNA template. It doesn’t have to grow.
• The original spotlight  on RNA was for therapeutics, for sick people. The bar is lower for sick people than for well people. Since  no RNA vaccine exists that has passed clinical trials, the risk of adverse reactions cannot be estimated from precedent. Speculation is the only guide.
• Moderna’s vacccine could be good, mediocre, or worthless. For the immediate need, mediocre satisfies. But it could also be evil.

Be warned: the immune system is possibly the most complex system that has come under the eye of man. The big picture is mostly darkness, with illumination of great detail.The sales pitch of the gambler should be taken with a grain of salt. No one, big talker or little voice, knows more than that.

An Urgent Note to The Powers That Be: The award to Moderna is justified. But it is extremely important to spread the money around.

Next: An old disease compared with COVID-19.