A quick update this week on the Johnson and Johnson vaccine - this is a vaccine that works a little differently from the two mRNA vaccines (Moderna and Pfizer) that are already being used. It uses an adenovirus (virus that causes common cold) that can get into cells but has been modified so it can’t make new copies of itself or cause illness. It carries a small piece of DNA that instructs vaccinated cells to make the spike protein from the coronavirus that causes COVID-19. The spike proteins that are made are not dangerous by themselves (because they aren’t attached to the full virus). When the vaccine causes spike proteins to be made, the immune system can learn to recognize them so that if it ever sees it again (from a natural COVID-19 exposure) it will be much more effective at targeting them and preventing infection.
The Johnson and Johnson vaccine is only a single dose, which is a major advantage compared to the current two-dose vaccines. In their study, it was 72% effective at preventing moderate severity COVID in the United States (it was a little less effective in South Africa where there is a variant that is proving more resistant to the current vaccines). Most importantly, they report that no one in the vaccinated group was hospitalized or died once they were at least 28 days out from the vaccine. The summary is that this vaccine is a little less effective than the currently available vaccines, but is still extremely protective against getting severe illness. The FDA review committee is meeting to discuss this vaccine on February 26th. If all goes smoothly, it will likely become authorized by the FDA a day or two later and available very early in March. Because it is a single dose and is easier to distribute (doesn’t have to be as cold) it will be an important tool in fighting COVID-19. At this point, we have no idea how many doses we might get locally or how quickly.
Inevitably, the availability of a single-dose vaccine will cause many people to ask which kind they should get if they have the option. My advice is to get whichever you have the opportunity to get first. All the vaccines that have completed their US studies have proven to prevent the most severe cases of COVID-19 very effectively. The more people we can get safely vaccinated in the near future, the more quickly we’ll put the worst parts of this pandemic behind us. Doing so is going to require the vaccines from all manufacturers, and there aren’t large enough differences in effectiveness that I would recommend waiting for any specific vaccine.