Q&A: Who needs a COVID-19 booster shot?
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As guidance emerges and COVID-19 vaccine booster shots become available, patients may have additional questions for their clinicians about whether they are eligible for a third dose.
It’s important to understand that a COVID-19 booster shot is not the same as an additional dose of vaccine, according to Douglas H. Jones, MD, cofounder of Global Food Therapy, cofounder and president of Food Allergy Support Team and director of Rocky Mountain Allergy at Tanner Clinic.
He explained that the FDA amended its emergency use authorization for the Pfizer-BioNTech (age 12 years) and Moderna (age 18 years) vaccines to allow an additional dose for patients with moderate to severe immunosuppression or deficiency.
“This dose is called an ‘additional’ dose and not a ‘booster,’” Jones told Healio, adding that there are 200 known primary conditions that cause immunosuppression or immune deficiency, and they can also occur secondarily to chronic conditions such as autoimmune disease or AIDS, medications, age or smoking.
“Some of these patients may not be able to make appropriate antibodies or T-cell immunity in response to vaccines,” Jones said. “It is important that they get evaluated to see if they can respond to vaccine or not.
“The additional dose should be given at least 28 days after the second dose and should match the vaccine used in the primary series,” he added. “The term ‘booster’ is reserved for those who had an adequate initial response to vaccination that is now waning over time.”
CDC recently recommended boosters for individuals who are aged 65 years or older and those living in long-term care facilities; those aged 50 to 64 years with underlying medical conditions; and those aged 18 to 64 years who are at risk for infection because of occupational or institutional exposure. Those who are aged 18 to 49 years with underlying conditions should weigh their individual benefits with risks and may consider a discussion with their doctor.
Boosters for non-immunocompromised patients may be needed as data show that the immune response declines with time if the immune response is based solely upon specific antibodies measured in the systemic circulation, according to Dennis K. Ledford, MD, member of the American Academy of Allergy, Asthma & Immunology (AAAAI) board of directors, the Ellsworth and Mabel Simmons professor of allergy and immunology at Morsani College of Medicine at University of South Florida, and the section chief of allergy and immunology at James A. Haley Veterans’ Hospital in Tampa, Florida.
“The importance of cellular or T lymphocytes to viral infections is critically important in preventing or mitigating disease, and T-cell responses are not reflected in antibody levels,” Ledford told Healio. “Furthermore, the level of antibody does not inform us on the ability to augment antibody production promptly if exposed to the pathogen, in this case, SARS-CoV-2. Thus, the data do not tell us of the ‘need for a booster’ but suggest there may be value in booster injections at some point. I will add this observation is not unique but is typical of immune responses in general, which is the rationale for boosters for other vaccines.”
Healio spoke with Jones and Ledford about the ongoing debate surrounding need for COVID-19 booster shots and common questions they are fielding from their patients and colleagues.
Healio: Will the different vaccines from Pfizer-BioNTech, Moderna and Johnson & Johnson vary in their need for a booster?
Jones: The CDC’s recommendations apply only to those who received the two-shot series of the Pfizer-BioNTech COVID-19 vaccine. The Advisory Committee on Immunization Practices stressed that the recommendations are interim and will continue to evolve based on data.
Ledford: The answer is unknown due to the rapid development of the vaccines and inability to date to collect long-term data. Pfizer-BioNTech and Moderna share a vaccine platform but differ in dose of messenger RNA. Johnson & Johnson uses a totally different platform. All three are utilizing approaches to vaccination of humans that have not been studied in large populations with long-term follow-up. At this point, we do not know about the necessity for boosters to any of the vaccines except what was previously stated about the Pfizer-BioNTech vaccine.
Healio: Are there certain populations, such as health care workers or people with pre-existing conditions, who definitely should get a booster?
Ledford: Medicine is an art based upon science, and the use of “always,” “never” or “definitely” should be used at one’s own peril. We simply do not know if anyone should “definitely” receive a booster. Risk/benefit balance is critical when we approach questions without strong evidence to inform the decision.
Individuals with impaired immune systems do not respond to vaccines in general. These subjects are the most likely to need a different vaccine strategy, such as a higher dose, boosters or adjuvants (substances that nonspecifically boost the immune response). I would consider individuals with impaired immune responses to be a priority in considering a booster. The immune response is quite variable, but advanced age, poor nutrition, chemotherapy, immune-suppressant medications, diabetes and other chronic diseases will impair the immune response. These would be my first considerations for a booster.
We need to keep in mind that there is no assurance that a booster will achieve the desired outcome if the immune response is impaired. However, impaired does not mean nonfunctional. It makes sense to provide a stronger stimulus with a weaker immune response. Yet common sense is often found to be wrong following good scientific studies.
The other side of the equation is the risk of the individual. People who cannot control their exposure to the general public or who provide care for individuals who are infected with COVID-19 are at increased risk for infection. Health care professionals, first responders and teachers are groups with a greater probability of exposure that they cannot completely avoid, and those with impaired immune systems are likely to need a “stronger” immunization. I conclude that these two heterogenous populations, those with poor immune response or reduced longevity of the immune response and those with increased, unavoidable exposure, should first be considered for boosters. Because we do not have long-term safety data on booster administration, I would defer giving boosters to the general public.
Healio: Do you think boosters will be necessary for the rest of the population?
Jones: It is unclear at the moment if the rest of the population needs boosters. We really have to continue to monitor the data with effective studies. We have to keep asking ourselves if the benefits of receiving boosters are adding enough to what the previously vaccinated immunity is already achieving and if that clearly outweighs the potential risks. I do not think we currently have the answers to those questions for the rest of the population.
Ledford: I think boosters are likely to be recommended for the general population based upon our experience with other coronaviruses and the immune response noted against these viruses. However, we have never used the current vaccine platforms for the general public, and we cannot assume that what was true of coronavirus immune response in the past will be the same as post-vaccine. As the prevalence or risk for COVID-19 infection declines, the benefit of vaccination will decline due to less disease, whereas the risk of vaccine boosters, if any, will not likely decrease. Thus, it is possible that boosters will not be necessary.
Healio: Are there any factors that will make boosters more or less effective?
Jones: Optimizing your baseline health and immunity by mindful, healthy eating and sleeping habits, daily activities, managing stress, maintaining adequate vitamin D levels and controlling other chronic health conditions are practices that are going to help the body and its vaccine response.
Response may be hindered by not doing the above, or if someone has had immunodeficiency or is on immunosuppressive medications.
Ledford: Effectiveness is a complex concept that incorporates the ability of the booster to increase clinically relevant immune response, the likelihood of an individual being exposed to the infection, the severity of disease that results from the infection and the side effects and cost of the booster. In general, giving boosters with a greater time interval — for example, 6 months between the primary series and the booster — and giving boosters with adjuvants would likely make the boosted immune response more vigorous or longer lasting. However, there also could be more side effects with measures to make boosters “more effective.” Also, if the probability of infection declines, the effectiveness of a booster will decrease due to less disease, the ultimate goal of vaccination.
Immune impairment, less risk for disease and greater vaccine side effects or cost would make boosters less effective.
Healio: Beyond this first potential booster, what is the likelihood that further boosters or immunizations will be necessary?
Jones: We are still in the process of analyzing this. We are currently not sure, as more data are needed.
Ledford: Coronavirus immunity in general declines relatively rapidly compared with some other infections. However, “spike protein” coronavirus vaccines (the current COVID-19 vaccines) provoke a remarkably strong, specific, protective immune response, particularly if an immune response that prevents serious disease or hospitalization is the priority. Minor viral illness is a normal event in human life, and if this is the result of subsequent SARS-CoV-2 infections, there is less need for boosters. Because there are segments of our population at risk for severe disease and even healthy people can be very ill with COVID-19, I suspect there will be annual vaccination for 1 or 2 years. This is speculation on my part.
Healio: Are you concerned about allergic responses to boosters, particularly among patients who had an allergic response to a prior dose?
Jones: If someone had an allergic reaction to previous vaccines, then they should consult with an allergist to discuss their options. An allergic reaction to one vaccine may not preclude a person from getting another type of vaccine depending on their situation. Otherwise, risk for allergy is quite low. Again, if there are concerns or questions or a history of previous reactions to vaccines or injections, I would consult with your doctor.
Ledford: Vaccines in general are incredibly safe. But if a side effect occurs, it can be a major problem for the individual. Allergic reactions to COVID-19 vaccinations are exceedingly rare, although anaphylaxis, a life-threatening allergic reaction, occurs more commonly with COVID-19 vaccines than with other vaccines, such as influenza. But this risk is approximately 7 per million vaccinated individuals, and these reactions almost always respond to prompt treatment. This should be compared with healthy people dying of respiratory failure or up to 30% of infected subjects having “long-haul COVID.”
I do not think the risk for allergy is a major concern, but I would be cautious in an individual who has experienced a serious reaction to the prior vaccinations.
I will add there have been other side effects including thrombosis and stroke that are more common with some of the vaccines and more common in certain populations — for example, young women who have received the Johnson & Johnson vaccine and more so with the vaccine only available in the U.K. These reactions are serious but are not “allergic” reactions as generally defined. Other problems are local swelling, fever, joint aches and the “blahs,” which again are not allergic reactions but reflect stimulation of the immune response. These latter problems would not affect my decision to recommend a booster.
Healio: Looking ahead, will changing vaccination patterns such as a significant increase or decrease in the number of people getting vaccinated impact whether booster shots will be necessary?
Ledford: Vaccination is not like most health care choices, as vaccination not only improves the recipient’s health but also improves the community’s health. One person accepts the risk of vaccination and provides protection to friends, neighbors, coworkers, family, strangers with whom they come in contact and the general population. Vaccination is being a good neighbor.
Vaccines have minimal side effects, but they do have them. If a large part of the population prefers not to receive vaccination, for whatever reason, this will increase the risk for vulnerable people and make boosters more of a necessity. There is also a greater chance that the current vaccine could lose efficacy over time if the virus is allowed to propagate in the nonvaccinated population. What we do affects others, just as when we drive or cough or sneeze.
For more information:
Douglas H. Jones, MD, can be reached at immunofitness@gmail.com.
Dennis K. Ledford, MD, can be reached at dledford@usf.edu.