The Janssen vaccine for COVID-19 (manufactured by Johnson and Johnson, and approved for emergency use) only requires a single dose to offer good protection, and is much easier to transport and administer because it can be stored long term at normal refrigerator temperatures. Those differences will greatly reduce the logistical overhead of mass vaccination. As production of the vaccine ramps up, it will become especially important in reaching smaller, more distant communities.
Similar to the Moderna and Pfizer vaccines, it doesn’t actually contain the material that your body is getting trained to recognize, the coronavirus spike protein. All three vaccines are designed to transport an RNA sequence into a small number of cells in your body. Those cells then produce and secrete a portion of the spike protein. The sudden presence of the foreign spike protein is what triggers your immune system to action, and teaches it what kind of antibody or T-cell response to use when confronted with actual coronavirus in the future. The Pfizer and Moderna vaccines contain bare mRNA, encapsulated in small globules of fat, which are designed so that they have a tendency to fuse with your cells and inject the mRNA into them. The Janssen vaccine uses a different vector to carry the RNA, an adenovirus which normally causes the common cold, but which has been modified so that it cannot replicate or cause illness.
Side effects will vary from person to person. I received the single dose vaccine on March 4, and experienced only mild symptoms. There was some injection site soreness, extending to the neck and shoulder muscles. I felt a little muzzy-headed for a few hours that evening, but after having a good night’s sleep, I felt much clearer. I had a very slightly elevated body temperature, about half a degree higher than normal, which made me a little bit uncomfortable for about a day.
This vaccine provides moderate protection after about two weeks, and better protection after about four weeks. That means that even if confronted with new variants, the chances of illness are reduced, and the chances of serious illness or hospitalization are greatly reduced.
I will be continuing to wear medical grade masks in the clinic, and ask that patients continue to wear masks during treatment whenever possible.