Your COVID-19 Vaccine Questions Answered
December 16, 2020
The first COVID-19 vaccines were rolled out recently, with health care workers receiving the initial wave of inoculations. A majority of Americans won’t receive their vaccines until at least the spring. But many have questions about the first available vaccine. We talked with University Hospitals infectious disease specialist Robert Salata, MD, to learn more about the Pfizer vaccine, which continues to be studied in clinical trials at University Hospitals.
Q. The vaccine requires two doses administered three to four weeks apart. What happens if I don’t get the second dose?
A. The second dose really maximizes the immune response. Pfizer analyzed their information after a single dose and found even 10 days afterward there was a rate of effectiveness of 54 percent. It then climbed steadily to the 95 percent level after the second dose. So it’s very important for people to understand that to get the optimal immune response, they need to return for the second vaccination.
Q. You are the principal investigator for the Pfizer trial at the UH clinical trial site. Do you have any concerns about the safety of the vaccine?
A. In all of the Pfizer vaccine studies, we are going to follow individuals for 26 months after their second vaccine to look at long-term safety issues, as well as continued duration of protection, so the public should be reassured about that.
What we have information on right now are short-term issues, and those look very favorable. In the U.S. Food and Drug Administration (FDA) analysis of the Pfizer vaccine, about 50 percent of people had some degree of fatigue and aches at the very beginning after being vaccinated. A third of people had fevers and chills. All of these were very short-lived, and most of them resolved within 24 hours, if not 48 hours.
Q. There are a number of vaccines in development and nearing approval for use in the United States in the next six months. Will I get to pick which one I get?
A. Probably not at the beginning because it’s going to be a supply-and-demand issue.
Q. After I get vaccinated, do I still need to wear a mask, wash my hands and maintain other measures against spreading the coronavirus?
A. After you are vaccinated, it will take a while to get full protection, including two doses and probably a period of two weeks afterwards. So people should still expect, though being vaccinated, to wear masks and practice all the other control measures that we’ve been talking about since the pandemic’s beginning. It takes a while for the immune response to rev up, and that will be even several weeks after the second vaccine is administered.
Q. How long will I be protected once I get the vaccine?
A. We can’t say for sure right now. This is one of the reasons we are looking at durability of protection in all of these studies out to at least two years. This virus can change or mutate as we see with the influenza virus, for instance, and that can cause either minor or significant changes in the flu virus so that we have to be vaccinated every year right now. There have been reported more than 40 changes or mutations in this virus, but so far, the good news is those changes have not impacted the clinical outcomes.
Q. How does the Pfizer vaccine and others like it work?
A. The major target of the immune response is the spike protein. If you look at a picture of the coronavirus, we have these projections on the surface, and that’s the spike protein, which allows it to attach to our own human cells, go inside the cells and take over the genetic material and machinery to make more virus. When that happens, the virus propagates and disseminates to other organs in the human body. With these vaccines, the idea here is we create antibodies that block that spike protein from ever attaching to our own human cells. The lack of change in the coronavirus spike protein through mutation is, I think, very encouraging that this vaccine will be durable, but it remains to be seen.
Q. What is the emergency use authorization this and other vaccines are going through?
A. Emergency use authorization is the first step to full FDA approval later, but it does mean that on the basis of the authorization, you can begin to use that product. And that has applied to several things that we now use, such as therapeutics, treatment for COVID-19, these vaccines, as well as even devices and testing. So there’ll be more information accumulating over time. When that is the case, the FDA will move in to give full approval. But that may take some time. There are several groups that were not studied in these current vaccine trials, as an example, pregnant women, those who are immunocompromised, those that have less stable medical conditions like uncontrolled diabetes as well as hypertension, cardiac, lung disease, etc. So, we need more information.
Q. Does emergency use authorization mean it’s safe?
A. Based on the preliminary data, it’s safe and it’s effective. And an efficacy rate that’s beyond our wildest hope. So far, we should be reassured by that.
Q. If you’ve already had COVID and you know you’ve had it, do you need the vaccine?
A. The answer is undetermined at this time, but I agree with many of the experts who say we should administer vaccine to these people as well. What may happen is they’ll be put farther back in line in getting the vaccine so we can prioritize other groups. There are examples of other vaccines that are used in people who have already had disease or infection, such as the shingles vaccine. So I think we’re going to see the same thing play out with the coronavirus vaccine, too.
Q. When can we expect the pandemic to end?
A. We need to get to a level of vaccinating well over 200 million folks in the United States to potentially achieve what is called herd immunity. That is a level where we can certainly make a dent in the cases of COVID and protect others in the environment and so on. That’s another important strategy. So we’re still in this for 2021, and maybe even into 2022. But I think we’ll begin to see a significant impact of the vaccines probably by the fall of 2021.
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