What reactions can I expect? And other COVID-19 vaccine questions answered by Wisconsin health experts

Much-anticipated COVID-19 vaccines are being distributed across Wisconsin starting in mid-December. Though widespread availability of the vaccine is still months away, we know you may have questions.

The Milwaukee Journal Sentinel has assembled a panel of experts from the University of Wisconsin to help answer questions from readers.

Please keep in mind scientists and doctors continue to learn much about the virus and the vaccines, and guidance is changing. They will provide the best information that is available. You can submit more vaccine-related questions here. 

RELATED:What we know so far about Wisconsin's plan to distribute COVID-19 vaccines

What is considered a strong effectiveness percentage for a vaccine? For reference, what are some of the effective percentages of vaccines that have been in use for awhile?

It depends on the disease. COVID-19 is an unprecedented crisis for which lower effectiveness would be acceptable. Of course, the higher the better. Most childhood vaccines are 90% to 99% effective in preventing disease.

— Ajay K. Sethi, PhD, MHS, associate professor of population health sciences, faculty director of masters of public health program, Department of Population Health Sciences at the University of Wisconsin-Madison

What is in the vaccine?

The main ingredient of the Pfizer and Moderna vaccines is a small strand of messenger RNA (mRNA). It is synthetic and does not come from the actual SARS-CoV-2 virus. The vaccine does not contain mRNA that would allow cells to make an entire virus particle. A person who is vaccinated produces an immune response that affords protection against getting COVID-19 without being infected with the SARS-CoV-2 virus. Two doses of either the Moderna or Pfizer vaccines are needed. 

— Ajay K. Sethi

What kinds of reactions to the vaccine can I expect?

This vaccine does show “reactogenic” tendencies in the Pfizer and Moderna trials. Reactions — or in medical speak, side effects — are headache, fatigue and muscle pain. This is actually a good sign that your body is mounting an immune response to the proteins created from the mRNA in the vaccine. This is NOT the same as getting COVID-19.

The CDC's Advisory Committee on Immunization Practices presented some small data that suggested the reaction may be stronger after the second dose, but the difference in numbers was still very small.

Severe reactions are different than side effects, and both Pfizer and Moderna are having their safety profiles evaluated by the FDA for Emergency Use Authorization. Safety is important and is not being skipped, even with the accelerated timeline. However, one-in-a-million severe reactions are still possible to find, as more people get the vaccine. These types of reactions are being closely tracked by VAERS (Vaccine Adverse Events Reporting System) through Health and Human Services.

— Devlin Cole, MD, MPH, preventive medicine resident, Department of Population Health Sciences at the University of Wisconsin-Madison

How do I know which manufacturer's vaccine I've received, and do I have to get the booster from the same manufacturer?

The easiest way to find out what brand you are getting is to ask! And yes, the booster must be from the same brand as the first shot.

In Wisconsin, we are using a hub and spoke distribution model, where large amounts of vaccine go to centralized freezer locations throughout the state and from there, smaller orders are distributed to regional vaccinating entities. The CDC is holding on to the second doses and shipping those vaccines a few weeks later so that the hub does not need to hold on to extra doses in the meantime. So please return to the same place where you got your first dose, and your second dose will be there, waiting for you.

— Devlin Cole

How long is immunity conferred after one dose? Two doses? Is there a time limit on the efficacy of the first dosage?

The FDA briefing document indicates that there is strong protection after one dose. Protection is greater after two doses. It is unclear how long protection might last after one dose of the vaccine.

— Ajay K. Sethi

If I've already had COVID-19, do I need to get vaccinated?

Yes. The CDC is recommending that all people, regardless of prior COVID-19 infection, get vaccinated when possible. If you have had a confirmed (via test) case of COVID-19 in the past 90 days, you could delay your vaccination while supplies are limited to let others get vaccinated first.

— Devlin Cole

Once I get the vaccine, do I still need to wear a mask and social distance?

The vaccine is extra protection, like a super mask, but it is not perfect. Even in very controlled trials, only 90-95% of people getting the vaccine were protected from developing COVID-19, so 5-10% still got sick. And out in the world under less perfect conditions, the number of people still getting sick with COVID-19 even with a vaccine could be higher. So yes, after you get vaccinated, you still need to wear a mask, socially distance and get tested if you think you have symptoms.

This is especially true if you have only gotten one dose of the 2-dose series. At the current moment, there is not enough data to say that one dose will protect you as effectively as 2 doses. You must get the second dose to complete the series for maximum protection.

— Devlin Cole

I've heard from a few sources that the new vaccine will alter your DNA. Is that true? If it is true, what does it mean?

No, this is not true. The vaccine does not alter your DNA. The Pfizer and Moderna vaccines are made from messenger RNA, which will be pulled into your own cells. Your proteins will “read” the RNA and produce the protein encoded on the RNA. This protein chunk is part of the “spike” protein, and it is how the coronavirus family got its name. The spike proteins surround the outside of the virus, making it look like a crown (corona). Your immune cells will see these proteins that your cells have produced and flag them with antibodies to destroy them. These antibodies will be stored in your immune memory.

— Devlin Cole

Is it safe for pregnant women to get the vaccine? Were they included in the trials? What about children?

Pregnant and breastfeeding women were not included in Pfizer and Moderna trials, so safety and efficacy numbers from the vaccine studies can’t be directly applied to this population. However, the CDC has identified that pregnancy puts women in a high-risk category for COVID-19. Pfizer included children as young as 12 years old in their trials since October. Moderna is starting to include children as young as 12 years old very soon.

— Devlin Cole

Contact Amy Schwabe at (262) 875-9488 or amy.schwabe@jrn.com. Follow her on Twitter at @WisFamilyJS, Instagram at @wisfamilyjs or Facebook at WisconsinFamily.