Mrrzy is correct that the mRNA vaccines are a new type. But I think the facts as we know them indicate that it is a far more targetting toward the virus type of vaccine and a far less body interfering type of vaccine. One of the reasons the new vaccines must be kept so cold is that the critical part of the vaccine is extremely delicate. It is there to do one thing and it will fall apart otherwise. The other reason is that there are no real additives to this vaccine the way normal vaccines have been formulated, hence it is really not as likely as the 'normal' vaccines to complicate the human resistance.

I think the mRNA vaccines are probably the safest ever prepared or manufactured precisely because of the technology behind them. They are a game changing technology.

This is Dr. McCoy territory.

Meanwhile, I believe the AstraZeneca vaccine is more of the 'normal' non RNA type and does not need to be stored at very low temps. It does have some additives as did the familiar forms of vaccines in the past.

I think a lot of initial reluctance to be inoculated in the immediate future comes from several main sources:

1) A feeling to 'not be first' along the lines of "Early bird gets the worm, second mouse gets the cheese."

2) People who may associate the virus AND the vaccine with Donald Trump.

3) People who are going to get the Chinese or Russian vaccine and may not feel these have been well vetted.

4) People who through cultural isolation or stigmatization have reservations to any organized medical community.

I think far more than 50% of the population will accept the vaccines in the near future.

Vaccines have a two hundred year history, going back to cowpox/ smallpox in Europe, perhaps longer in other parts of the world. They have had complications and problems historically, but they are true human-made miracles.