Are the side effects of the second COVID vaccine worse than the first? Your coronavirus vaccination questions answered.

Michael Berry got his first dose of the coronavirus vaccine at a big clinic in Rockville run by the Montgomery County Department of Health. It was March 9, and the 72-year-old said he received a shot of the immunization made by Moderna.

A Silver Spring resident, Berry said he was told to expect a series of emails when it was time for him to schedule an appointment for his second dose. (Moderna says patients should get their second shot four weeks after the first.)


But April 9 marked four weeks to the day, and Berry said no such email arrived.

He called around but got caught in a cycle of recordings, dropped calls and telephone trees. Anxious to achieve maximum immunity considering his age and existing health conditions, Berry even wrote his primary doctor. He was concerned about the consequences he didn’t know of receiving the second dose late and what would happen if he can get a different brand than the original immunization.


“I’m a little frustrated and distressed about the whole thing,” Berry said, “and worried.”

Berry’s experience echoed that of other Marylanders concerned about protecting themselves. So The Baltimore Sun sought out to answers to some of the most frequent second dose questions. Here’s what we found:

My second dose date has come and gone. Is it time to panic?

No, don’t panic. While the U.S. Centers for Disease Control and Prevention recommends the vaccines “as close to the recommended interval as possible,” it maintains that the vaccines may be administered up to six weeks after the first dose. After that, the picture is less clear.

There’s limited data about the vaccine efficacy for getting the second shot more than six weeks following the first, said Dr. Boris Lushniak, dean of the University of Maryland’s School of Public Health. “The true answer depends on the information that we’re still gathering from the vaccines and the immune response.”

But Dr. William Moss, executive director of the International Vaccine Access Center at the Johns Hopkins Bloomberg School of Public Health, said the critical clinical trials for Pfizer and Moderna only examined intervals of three and four weeks because they wanted to expedite the process. Those schedules are short compared to most vaccines, and some countries like the United Kingdom and Canada have explored delaying the second dose in favor of getting more people first doses.

“From an immunologic point of view, it’s likely that if you got it at six weeks or eight weeks or even 12 weeks, you’re still going to have a good immune response,” Moss said. “In fact, it could be better.”

If you miss your second dose appointment, who can you call?

Dr. Kirsten Lyke, a professor of medicine at the University of Maryland School of Medicine, said its important not to give up if you miss your second dose appointment or couldn’t schedule one through the same provider of your first shot.

Issues with second dose appointments make all the more important your vaccination card, which should include the date of your second dose and the type of vaccine you got, Lyke said. Check the second dose date and try to schedule an appointment elsewhere, like a mass vaccination site.


The Maryland Department of Health advised vaccine providers that it’s incumbent upon them, not the patient, to schedule the second dose appointment. “This dose should be at the same location with the same provider,” state officials told vaccinators in a weekly bulletin. The officials also said patients requiring second doses should be prioritized.

First, people who missed their second dose should contact the provider who administered their initial immunization, said Charles Gischlar, spokesman for the Maryland Department of Health.

If that doesn’t work, you can make an appointment for a second dose with at a state-supported site by calling 855-MDGOVAX (855-634-6829), Gischlar said.


How many people are following through with their second doses?

About 91% of people in Maryland who had enough time to receive a second dose between Dec. 14 and Feb. 14 completed their vaccination series, according to a CDC study.

The rate in Maryland was higher than the average of 88% among 59 states and territories, the study shows.

Do you have to get the same brand second dose as the first dose?

Yes. If you got a dose of Pfizer-BioNTech or Moderna for the first shot, you should get the same for the second shot, according to the CDC and experts who study vaccines.

The safety and effectiveness of mixing vaccine products has not been thoroughly evaluated, experts say. The CDC even recommends delaying the second dose, up to three weeks for Pfizer or two weeks for Moderna, “to receive the same product rather than receiving a mixed series.”

That’s probably because there’s no, or very little, data about mixing the products, said Lushniak, who served as the U.S. deputy surgeon general from 2010 to 2015. He said during clinical trials Pfizer and Moderna collected and presented data specific to their products alone.


“That’s the danger of mixing. We have to rely on the data of scientific fact,” he said. “The real recommendation needs to be loud and clear: get the second dose the same as the first.”

However, Lyke pointed out, countries like the United Kingdom are studying mixing products and types of vaccines, like mRNA vaccines (Pfizer and Moderna) and adenovirus immunizations (Johnson & Johnson).

Is the second dose actually any different from the first?

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“They’re the exact same,” Lyke said.

However, while the doses are identical, your body’s response to the second dose could be a little different to what you experienced after the first.

“When you’re first exposed to the Pfizer or Moderna vaccine your body has a primary immune response,” prompting it to make memory immune cells, Moss said. “When you get the second dose the response is much faster” because your immune system recognizes what it’s up against.

Are the side effects worse after the second dose?

There’s a good chance the side effects following your second shot are worse than those you experienced after your first, according to the CDC.


That’s because your body, through the memory immune cells it developed, recognizes the vaccine, Moss said. The part of the immune system that’s causing the local reactions near the injection site, like soreness or redness, or the more systemic reactions, the fever and fatigue, “they are more reactive after the second dose and it’s because your immune system responding more aggressively.”

However, you shouldn’t worry. The CDC says side effects like pain, redness and swelling near the injection site and tiredness, muscle pain, fever and nausea throughout the rest of your body are signs it is building protection. Those symptoms should abate within a few days, and you can take over-the-counter pain relievers like ibuprofen and acetaminophen to counter the discomfort after receiving your shot.

You also shouldn’t be concerned if you have no or limited symptoms; everyone’s body responds differently, Lushniak said. He and his wife both got vaccines. He felt tired for about 24 hours; she had an awful headache and couldn’t get out of bed. “One family, two physicians getting reactions quite differently.”