Hi Jeannette - In answer to your question about whether the vaccine would prevent Covid if you were exposed during travel, then had the shot the next day.

Immunity from a vaccine injection is not instantaneous, therefore the answer would be no. The injection activates production of antibodies which must build up in your system. People with weakened immune systems, or older people usually take longer to form the antibodies than young, healthy individuals. With a typical, single-injection vaccine like the flu shot, protection is considered to begin at about 2 weeks, and be fully active at about a month. The Covid vaccines currently approved for use require 2 injections, 2 - 4 weeks apart, so I would believe you should not count on any protection before a second shot.

My husband and I are having a similar discussion, as are many of our snowbird friends. Other important considerations, no matter how much we dislike snow and cold... The warmest places currently seem to have the highest levels of infection and hospital occupancy rates, and the lowest rates of mandated precautions or people voluntarily taking precautions. This increases risk during day-to-day activities. Large numbers of people traveling from many places to the warmth are potentially bringing the virus along. If they do not self-quarantine upon arrival, that means increased risk of exposure. Just as critical, all these factors can mean decreased availability of medical care for any other accident, injury or illness.

I hope this helps with your decision-making.
Sue