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Boosters and sports: Dr. Petri answers your COVID-19 questions

University of Virginia immunologist and COVID-19 researcher Dr. William Petri continues to answer reader questions about COVID-19. Send your questions to Lynne Anderson at, and she will forward them to Dr. Petri.

I’m vaccinated, boosted, wear my mask whenever necessary, and also love sports. But, I hope the doctor can explain to me the usefulness of basketball players (among other sports) wearing masks while sitting on the bench, then going into a game sweating, possibly bleeding, spitting, etc. all over each other while maskless. It seems to make a mockery of prevention’s raison d’etre. What am I missing? Is it just that half a loaf is better than no loaf at all?

I think you have asked what is on all of our minds, especially as we near the end of the omicron wave of the pandemic. What is crystal clear to me is that COVID-19 is caught through inhalation of the virus, and that we are not out of the pandemic yet. So long as people are so ill as to be hospitalized or die (100,000 in the hospital and 2500 deaths in one day last week in the US), preventing transmission through masks and more importantly through boosted vaccines is in our individual and community’s best interest. The question is essentially "What are reasonable compromises to make with mask wearing?" For me this translates to wearing my mask 100% of the time while working at UVa Hospital, and in contrast not wearing it while seated at an indoor restaurant. Not perfect but maybe a reasonable compromise.

Early in the pandemic, Dr. Fauci made a comment related to the virus and its not being as transmittable in water. My question focuses on those who do water aerobics vs swimming. I have been boostered, have had a COVID breakthrough in November, and am the only one to wear a mask in class. We are all vaccinated and work out 3-6 feet apart, but there is a lot of huffing and puffing. Should masks be worn?

Congratulations to you and everyone in your water aerobics class for maintaining good health through exercise; that is “hay in the barn,” as they say, and portends for a healthy future. As far as mask wearing, a significant exposure (one that would require you to quarantine for five days) is one where you are less than six feet away from an infected person for more than 15 minutes in a 24-hour period. So it does sound like wearing masks for this indoor exercise would make sense until we are through the omicron wave of the pandemic. And great too that that you are vaccinated and boosted – I am sure this was a major reason that you have recovered from the breakthrough infection, and are able to enjoy the camaraderie of water aerobics!

Like millions of older Americans, I welcomed the arrival of the vaccines and eagerly got the first available shot, which turned out to be the J&J vaccine. The efficacy of the J&J vaccine led me to get a Moderna booster when I was eligible.

The medical profession frequently says that with two shots and a booster, an individual is adequately protected from the virus. With one J&J shot and a Moderna booster that was a half dose of the standard Moderna shot, I worry that I am not as adequately protected as those who received two initial shots and then the half-dose booster. Should I attempt to get another half-dose Moderna booster or should I re-start the vaccine process with two full-dose shots and then the half-dose booster? Thanks for the help.

There is actually a clinical trial from the University of Maryland that fortunately addresses your question. I hope you will be reassured to know that boosting the J&J with the Moderna vaccine led to equivalent protective anti-spike antibodies as a Moderna boost of a Moderna primary vaccine series. So no need at present for another vaccination or booster. However, more boosters are in all of our futures, since immunity to the coronaviruses is not life-long, as it is to some other viruses such as measles. So perhaps as early as this fall I expect that if COVID-19 infections remain frequent, that there will be a recommendation from CDC for another booster for all of us.

Thank you so much for all of the advice and research you have provided before and during the pandemic. I am an immunocompromised individual, I have Rheumatoid Arthritis and Type 1 Diabetes, and I take infliximab and methotrexate to control my arthritis. I am up-to-date on my COVID vaccines, but continue to hear that moderately to severely immunocompromised patients may not respond as well to the COVID vaccine, and may be more susceptible to severe complications or death if infected with COVID. I also have read that you are working on a preventative antibody similar to Evusheld that may be available to those that did not respond well to the vaccine.

I am confused however on how I am supposed to know if I responded to the vaccine, and if I would be a candidate for the preventative antibody treatment. My doctors continue to advise me that if I check my antibodies, it will not determine if I am protected against COVID and so I should not bother to check them. But how else am I supposed to know if I should consider the preventative antibody treatment in the future? I would love to begin to spend more time with my family and perhaps travel, but I still feel unclear about my risks and how I know if the vaccine worked for me or not. Thank you in advance for any advice you can offer.

Since you are immunocompromised because of the medicines you are taking for rheumatoid arthritis, the CDC has recommended that you get a 4th shot of the COVID-19 mRNA vaccine at least 3 months after your last booster. You could also get tested after that booster to see what level of anti-Spike antibodies are circulating in your bloodstream. Your doctors are correct that we do not yet know yet what level of anti-Spike antibodies is needed for protection. However since you are immunocompromised there is some risk that these antibodies could be very low or zero. So I do recommend that you have them measured in order to help determine Evusheld would be appropriate. Evusheld is the cocktail of two monoclonal antibodies against the spike glycoprotein that has been shown to prevent COVID-19 infection. It is used for those who do not respond to the vaccine.

My husband and I are in our mid-70’s, and received our 2 Pfizer vaccinations in March 2021. We received our booster in October 2021. We’re rapidly approaching (if not there already) the time when our protection will wane significantly. I’m concerned that we’re not hearing any “official” conversation about beginning to administer a second booster to those at higher risk. This morning I read in the NYT an article about research around the effectiveness of a fourth shot.

From The New York Times: Israeli experts recommend offering a fourth vaccine dose to people age 18 and over. The Health Ministry cited early signs that a fourth shot might help protect against serious illness, but has yet to approve the panel’s recommendation.

Please let us know what US public health experts and officials are considering at this time. The clock’s running, and we, along with many of our friends, are very concerned.

The first thing that we are taught in medical school is to “first do no harm.” The debate around giving a second booster for non-immunocompromised people revolves around the benefits vs risks. The early unpublished (not peer-reviewed) data that you mention from Israel is from 400,000 people who received the 4th shot vs 600,000 who did not. The 4th shot was associated with a threefold reduction in serious infection in those aged 60 and older. If this data is accurate, then the discourse will change, because the prevailing wisdom had been that the benefit of a 4th shot would be mostly in prevention of mild or asymptomatic infection. So active discussion of benefits at present. The mRNA vaccines from Pfizer and Moderna are very safe, with the most common problem sore arms, fever, fatigue and/or muscle aches which are almost always gone within 48 hours. More of concern is that in about 1/10,000 young men inflammation of the heart, or myocarditis develops, which sometimes results in hospitalization but in most cases resolve spontaneously. Thus the importance of balancing benefits from risks.

If an adult has not received their booster because it has not been 6 months since their second dose of the vaccine, are they considered a ‘safe’ contact until they reach the 6 month mark? If a family wants to meet indoors and some family members are boosted, but some are not because they are not yet due for their booster, do any extra precautions need to be taken? If children are to be included in a family gathering where the adults are fully vaccinated, but the children are not vaccinated or only partially vaccinated, should masks be worn? If so, by whom – adults, children, or both?

For a family gathering as you describe, it makes most sense to ask anyone who is having cold or flu symptoms not to attend, and even do home tests for COVID-19 for everyone attending the event. As far as boosters, the current recommendations are to receive the booster shot 5 months after receiving the primary vaccination with the Pfizer or Moderna and 2 months after J&J vaccine. This is based on the decay in anti-spike antibodies after vaccination, so up to five months after vaccination protective levels are still present and one is “fully vaccinated”. Fortunately we are exiting the omicron wave of the pandemic, and hopefully these precautions will become less important.


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