Your COVID-19 vaccine questions answered with University Health’s Dr. Alsip

How long does vaccine last? What are the side effects? What happens if you skip the second dose?

SAN ANTONIO – With the COVID-19 vaccines still being relatively new, it’s understandable that many people still have questions about how it works, who should get it and how much protection it offers.

University Health Chief Medical Officer Dr. Bryan Alsip answered some of the most frequently asked questions about the COVID-19 vaccines. You can read his responses below and watch a video in the video player above.

How much protection does a first dose of the vaccine provide?

The best protection comes from two doses in a two-dose series, but data available for the two vaccines that are currently authorized indicate that a single dose offers some protection anywhere from 50 to 80 percent efficacy.

How soon do you start developing immunity after the first dose?

The initial response comes around two weeks after your dose of vaccine, it’s about as long as it takes for your immunity to kick, in your antibodies to develop and so forth.

What do I do if I feel bad after getting the vaccine?

Side effects are common with both vaccines that are currently authorized, but they tend to be relatively minor. Most people report either tenderness or swelling at the site of the injection, headache, fatigue, sometimes body aches and rarely fever. And in those cases, for the most part, people can take acetaminophen or Tylenol or ibuprofen to help with those symptoms. Generally speaking, they only last 24 or 48 hours as well.

What happens if I don’t get my second dose?

Well, nothing happens, per say, but so far, we really would like people to continue to take that second dose, if possible, because that really offers the highest level of efficacy, probably around 90 to 95 percent for both the vaccines that are currently available.

What happens if the second dose is delayed for some reason?

Since we want folks to take the second dose in the two-dose series, the goal would be to then get it as soon as possible. Like most vaccines, you can always take the second dose later than the interval indicates. But since the studies really were done based on the twenty one day or twenty eight day interval, it’s important to try to get that second dose close to that as possible.

Is the booster different from the initial dose?

The (second) injection is the same -- same dose, same volume, but it does boost your immunity, hence the name to offer, you know, the highest level of efficacy from the vaccine. And presumably it also allows the vaccine to work longer over a period of time.

Do we know how long the vaccine protection lasts?

We don’t. There are some recent reports from Moderna that say that they feel it lasts at least a year and that may be also true for the Pfizer vaccine, given they’re very similar. So the hope is that would be something that would at least be a year in terms of protection.

Could I get a different vaccine if that’s available when the time comes from my second shot?

It’s currently not recommended to mix the vaccine, so whatever brand you receive for your first dose, you should seek to get the same for your second dose.

Should pregnant women receive the vaccine?

The COVID vaccine is indicated for pregnant women, and pregnancy is on the list of priority conditions for Phase 1B. That’s outlined by the Texas expert vaccine allocation panel. I think it’s often recommended that pregnant women discuss their particular situation with their health care provider just to see what works best for them.

Should I get the vaccine even if I’ve already had COVID-19?

For COVID infection, the natural immunity from that is relatively unknown and it can vary amongst individuals. And so it’s felt that the vaccine, which has been shown to be effective in reducing symptomatic disease, is a better way to ensure immunity and also thought to last longer.

When I am vaccinated, can I quit wearing a mask?

The answer is no. The clinical trials that were used to study the vaccines didn’t actually determine whether the vaccine prevents transmission. And so it’s very possible that getting a vaccine could reduce your likelihood of illness, but still allow you to transmit that disease to somebody else who either hadn’t been vaccinated or is still vulnerable. So the recommendations are at least until we have enough people who are immunized to maintain the protections that we’ve been doing.

If I and my friends are all vaccinated, can we go without masks with each other?

If everyone that you’re around in close proximity has been immunized, it’s very likely that you’re all are protected from the symptomatic effects of disease. But since any of you could still potentially transmit the disease, you have to be very cautious about how you are around others. I think that’s the important message to remember.

Does the vaccine prevent the illness or just symptoms?

We don’t actually know whether the vaccine prevents you from getting infected, but we do know is the efficacy data support what is essentially the prevention of symptomatic disease. So you’re much less likely to become ill if you get the vaccine than if you didn’t have the vaccine.

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About the Author:

Julie Moreno has worked in local television news for more than 20 years. She came to KSAT as a news producer in 2000. After producing thousands of newscasts, she transitioned to the digital team in 2015. She writes on a wide variety of topics from breaking news to trending stories and manages KSAT’s daily digital content strategy.