The Medical Minute: What to expect post-vaccine

February 17, 2021

HERSHEY, Pa. — What if it makes me sick? What if it doesn’t work? How long will it protect me? For some people, anxiety over what may happen after they get the COVID-19 vaccine seems to almost outweigh the relief of getting protected.

“People are approaching this vaccine with more hesitation because it was approved quickly, but that really just speaks to how far we have come in vaccinology,” said Dr. Mohammad Y. Ali, infectious disease doctor with Penn State Health Holy Spirit Medical Center. “This vaccine went through all the same rigors and reviews by independent data and safety committees as any other vaccine. No corners were cut.”

Here are some common questions and answers that can help ease concerns:

What if I feel sick afterwards? Does it mean I have COVID-19?

No, don’t panic. “Common symptoms such as headache, fatigue, body aches and fever are reactions we might expect to any vaccine. You’re making antibodies, and it’s actually a good sign that your immune system is doing what it’s supposed to do,” said Dr. Jillian Ventuzelo, a family physician at Penn State Health St. Joseph Medical Center.

I’m dreading my second dose — I’ve heard reactions are worse.

Reactions to the first vaccine are usually mild — maybe a little fatigue and a sore arm — while studies have shown a stronger reaction to the second dose. That makes sense, doctors say.

“Your body made preliminary antibodies after the first dose, and they’re more robust as you are creating the memory immune cells to fight future exposure,” Ventuzelo said. After her first dose, she had a sore arm, but after the second dose, she had chills, body aches and extreme fatigue that caused her to miss a day of work. Her symptoms abated and then returned, but she was better within 48 hours, she said. Ali had a sore arm and achiness that began 24 hours after the first vaccine and lasted 48 hours, and with the second dose, he experienced a little more pain at the injection site and fatigue that began 12 to 14 hours later and lasted several days. However, he said he was able to work 10-or-more-hour days through it all.

Are there any symptoms I might experience later for which I should seek medical care?

Any symptoms of anaphylactic shock, such as low blood pressure, an elevated heart rate or trouble breathing, are very rare and usually happen within 30 minutes, which is why people are asked to sit and wait after getting the vaccine. Any subsequent swelling, redness or warmth at the injection site that could signal an infection or developing hives warrants a call to your doctor, Ventuzelo said.

If I don’t have a reaction, does it mean the vaccine didn’t work?

No. Everyone’s immune system reacts differently. Reactions also may have to do with age, doctors said. People under age 55 tend to have more severe symptoms because their immune systems mount a harder fight.

Why do I still have to wear a mask and social distance if I’m vaccinated?

“The trials looked at the prevention of symptomatic disease, so we don’t know if the vaccine will stop asymptomatic spread,” Ali said. “You could be a carrier with no symptoms and transmit the virus to a person who is not immune.” Lifting the masking and distancing protocols will come only when community transmission has been significantly decreased through natural or acquired immunity, he said.

I’m planning to travel after I get the vaccine — do I still have to get tested before I go?

Yes — because we don’t know for sure if the vaccine protects against asymptomatic transmission, doctors said.

If I still have to take all the precautions I took pre-vaccine, what’s the point of getting it?

“We know the vaccine is stopping mild, moderate and severe symptoms and stopping hospitalizations. By getting it, you’re saving yourself from complications and potential hospitalization,” Ventuzelo said. In addition, getting vaccinated gets us closer to stopping community transmission and protects those who can’t get vaccinated due to contraindications, she said.

Should I get vaccinated if I’ve already had COVID-19?

If you’ve had COVID-19 in the past 90 days, you could postpone getting the vaccine because it’s rare you will get the virus again so soon; however, there’s no harm in getting it as long as you are over the acute illness and isolation period, Ali said.

How long will the vaccine protect me?

No one knows yet. “Vaccine manufacturers will be evaluating when immunity wanes, so we will know more as time goes on,” Ali said.

Will the vaccine protect me against the mutated viruses I’m hearing about now?

Preliminary studies on the U.K. variant have shown the vaccine is protective against severe illness, Ventuzelo said. Whether the variants will evade immunity remains to be seen, but that’s no reason to skip the vaccine, Ali said. “If you get the chance to get it, do it,” he said. “It’s the only way out of this at this point in time because it’s so rampant.”

Related content:

The Medical Minute is a weekly health news feature produced by Penn State Health. Articles feature the expertise of faculty, physicians and staff, and are designed to offer timely, relevant health information of interest to a broad audience.

(Media Contacts)

Last Updated February 25, 2021