Are you concerned about getting one of the new COVID-19 vaccines as soon as they are approved? We have no long-term safety information because no one has more than 10 months of experience with this disease. However, we do have decades of experience with other vaccines. The Pfizer and Moderna vaccines are expected to be safer than previous vaccines because they do not use viruses, either killed or live. Instead, they use messenger RNA (mRNA), genetic material that prevents infection because it stimulates your immune system to recognize and destroy the key that allows the virus to get into human cells. The Oxford–AstraZeneca vaccine is made from a harmless cold-causing adenovirus that was isolated from chimpanzees and modified so that it prevents the virus that causes COVID-19 from getting into and infecting human cells. Other vaccines currently being tested use similar processes.

Diana and I plan to take the first available vaccine for COVID-19. Diana has pulmonary fibrosis and has scar tissue covering more than 50 percent of her lungs, and I am 85 years old, so we definitely cannot afford to get this disease that specifically targets the lungs and older people. We will take the first vaccine that is available in our area, and hope that it will be either the Pfizer or Moderna vaccines that use the mRNA technology.

What is a mRNA Vaccine?
Rather than using live or dead viruses, scientists make the mRNA for these vaccines in a laboratory. The mRNA teaches your immune system to prevent the COVID-19 virus from getting into your cells. If mRNA was injected into you, your own human immunity would immediately destroy it just as it destroys invading germs, so the scientists covered the laboratory-made mRNA with a layer of fat (lipid nanoparticles) that hides the mRNA so your immunity does not attack and destroy it (Mol Ther, Nov, 2008;16(11):1833–1840).
• Messenger RNA tells your cells how to make various proteins that are necessary for life. The lab-made mRNA in the COVID-19 vaccine specifically stimulates your cells to make the “spike protein” just like the ACE2 receptors that are on the surface of the coronavirus that causes COVID-19. The ACE2 spike protein is the key that allows this coronavirus to get inside human cells. If the virus that causes COVID-19 did not have the spike protein, it could not get into your human cells and would die very quickly after getting into your body.
• The spike proteins made in your body when you get the vaccine cause your own cells to make antibodies that will attack and destroy that spike protein (Nat Microbiol, 2020;5:562–9).
• If and when you are infected with the coronavirus that causes COVID-19, your immunity quickly recognizes and destroys the spike proteins on the invading virus. Your immunity does not destroy the virus, but the virus dies soon after it enters your body because it cannot get into your cells and thus you are protected from that infection.

Have Other mRNA Vaccines Been Tried?
MRNA vaccines have never been generally used, but they have been developed for other infectious diseases: rabies, influenza, cytomegalovirus, and Zika. The rabies mRNA vaccine looks promising (Lancet, 2017 Sep 23;390(10101):1511-1520), and Moderna and German researchers published phase I results of two mRNA vaccines against influenza (Vaccine, May 31, 2019;37(25)). Moderna announced results of the phase I study of its mRNA vaccine against cytomegalovirus in January 2020 and its mRNA vaccine against Zika in April 2020, and reported that they produced antibodies to these viruses.

My Recommendations
Scientists still have not proved how safe the vaccines for COVID-19 really are. Health care workers and people at high risk for complications are likely to feel the same urgency we have, and they will be high up on the list of people to receive vaccines as soon as they become available. Other people may not feel this urgency and have the option to wait until more data has been collected. However, please consider your own role in helping to end this pandemic; re-read my recent article on herd immunity.

Widespread distribution of vaccines should be underway by April or May of 2021. Meanwhile, please continue to do what you can to help limit spread of the disease and to protect yourself:
• Wear a face mask any time you expect to be close to people who are not members of your household.
• Try to stay at least six feet away from other people.
• Avoid anyone with respiratory symptoms.
• Use 20-second soap hand washes frequently throughout the day.
• If you feel sick, stay home.
• If you decide to travel, go by car if possible. Personally, I am avoiding group travel such as trains, planes, buses and ships.
• Spend lots of time outdoors. Transmission of the virus occurs most often in closed spaces, particularly crowded places or rooms with poor air circulation.