Press "Enter" to skip to content

Dr. Petri dishes on COVID, answering reader questions

Dr. William A. Petri, an immunologist at the University of Virginia School of Medicine, answers this week’s questions from readers on COVID-19. Dr. Petri will keep dishing on COVID-19 and answering your questions each week in The Daily Progress for as long as you have questions. Send them to Editor Lynne Anderson at:, and she will forward them to Dr. Petri.

1. Our family is having a small (20-25 person) family reunion in Arkansas after Thanksgiving. The rule is that those who attend should be fully vaccinated, and all the adults have been. However, there are two children, ages 8 and 12, who are not vaccinated. They had COVID-19 in June of 2021. The family (located in Arkansas) took the appropriate precautions in the home, and the parents, both vaccinated, did not come down with it. For the reunion indoors, adults are not asked to wear masks; however, the two children are being asked to. My question is: Are the two children who have had the disease significantly more likely to spread the disease or to be infected than those who completed their vaccinations in March of 2021 and are not yet eligible for boosters?

I hope that the Pfizer vaccine will be approved for children 5-11 in the next few weeks so that the 8-year-old will be vaccinated (and of course the 12 year old already is eligible to be vaccinated. Then you will not have this dilemma that I imagine could lead to Thanksgiving family strife! I also agree that you are thinking about this correctly; there is immunity conferred by prior infection which diminishes the risk that the children will be a source of spread of COVID-19.

This, of course, leads to other questions: Should everyone be wearing masks? Social distancing? Does it make a difference that the children and their aunt and uncle will be attending a football game the day that the two-day family reunion begins? Does it make a difference that this reunion is taking place in Arkansas, not Virginia? All of the things that you mention may cause a small increase in risk, but to me it makes sense in a family gathering to only have the unvaccinated family members masked.

2. My parents were going to visit last weekend, but my mother had a breakthrough COVID-19 infection (fortunately not serious), and I was concerned about the risk of her transmitting it to me and my fiancée. We are both vaccinated. My mother was two weeks out from being diagnosed when she was going to visit. Am I being overly cautious?

It would have been fine for your parents to have visited, but good for you for being so cautious. Each of us can contribute to ending the pandemic by doing cautious things, most importantly vaccination but also wearing masks indoors in public places and practicing proper quarantine and isolation procedures. “Quarantine” is what you do if you have been exposed to someone with COVID-19 and “isolation” is what you do when you have COVID-19. In most cases isolation and quarantine can end 10 days after diagnosis. The exception is if someone is still having symptoms (wait another day after the symptoms have resolved), or if someone was so severely ill as to be hospitalized, when one should wait 20 days. I hope your parents can visit next weekend!

3. I am 75, and I had 2 doses of the Moderna vaccine. Since Moderna doesn’t have a booster yet, is it safe to get the Pfizer booster?

First I think you should be reassured that the Moderna vaccine protection is not so far showing evidence of wearing off or diminishing with time, so you are likely pretty well protected right now. Second, the FDA likely will approve the Moderna booster later this month, so you don’t have long to wait. Finally, the NIH started mix-and-match vaccine trials on June 1, where participants were boosted with a different vaccine than the one they originally received 3-4 months prior, so there should soon be some data soon on the advisability of mix-and-match. So I think being patient and waiting a few weeks will pay off. Hope this helps!

4. Do you think the term “breakthrough infection” is a misnomer? It implies that there is some magical-force field that keeps a virus from entering our body. This bothers me because “breakthrough infection” implies that the vaccine has failed. In reality, the virus can freely get into the body, usually through the nose, but is prohibited from replicating due to antibodies that attach to the spike protein which the virus needs to enter cells. Because the virus most often enters through the nose and most tests for the virus are carried out by swabbing the nose, there may be a positive test (the so-called “breakthrough infection”), but the vaccine is indeed working as it was designed to do.

Thanks for this interesting question. Actually most of the breakthrough infections had symptoms of COVID-19 in one study of over 4,000 vaccinated healthcare providers. Fortunately very few were so severe as to require hospitalization, so the vaccine did fail, but the failure was not so bad as to put lives at risk. This is the reason for booster shots being recommended for the Pfizer vaccine recipients (and soon I imagine for Moderna and J&J). Current guidelines for boosters are everyone age 65 and older, and anyone 18 and older who has an underlying medical condition or is in a higher risk occupation (healthcare, retail, agriculture).

5. I am 71 years old and have chronic lymphocytic leukemia (CLL). I had no antibody response to any of the 3 Moderna vaccinations I received. For CLL patients and other immunocompromised people who do not have a vaccine response as measured by detectable antibodies, is there hope of other treatments that might provide some level of protection for us now or coming in the future? In one article I read, someone said, “It is NOW time to give monoclonal antibodies to ALL blood cancer patients who don’t respond to vaccines. . . especially if the long acting forms are used.” What do you think?

I am sorry first about the diagnosis of CLL and also that the vaccine did not generate an antibody response. You are correct that an injection of the monoclonal antibodies against the coronavirus spike glycoprotein do act to both prevent and treat COVID-19. In fact, here at UVa, we led one of the clinical trial sites that demonstrated this (and thanks to the members of our community who helped everyone out by participating in this trial). The only reason not to give you the monoclonal antibodies right now, even though they are extraordinarily safe, is that you would need to be re-dosed with them every few weeks. Because supplies are limited the current approach is to wait to administer them to you until you have a COVID-19 infection or know that you have been exposed to the virus.

6. If having a case of COVID-19 gives us antibodies, and if immunity due to the presence of antibodies protects us from COVID-19, why don’t we offer antibody testing to those who don’t want the vaccine?

I agree this makes perfect sense, except that we don’t know yet how high the antibodies need to be to provide protection. So measuring antibodies right now could provide false reassurance. What we do know is that even if you have had COVID-19, you can benefit with added protection by being vaccinated.

7. Two children in Virginia died recently from COVID-19. I’ve heard that unvaccinated adults put children at risk by allowing the virus to continue to spread. Is this true?

Yes. Unvaccinated adults place children at risk because they can transmit COVID-19 even if they are not having symptoms. A good way to protect your child is by vaccinating yourself.


Be First to Comment

    Leave a Reply

    Your email address will not be published. Required fields are marked *