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COVID-19: Delta Variant, Third Vaccine Dose, and More

September 13, 2021

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Community Conversation: COVID-19 Update

An infectious disease expert shares why it’s more important than ever to be vaccinated

COVID-19 cases are on the rise again. In this Community Conversation on August 20, 2021, Jason Kessler, MD, infectious disease specialist and section chief of Infectious Disease at Morristown Medical Center, shares what you need to know about the Delta variant, third doses of the COVID-19 vaccine for the immunocompromised, and why it’s more important than ever to be vaccinated.

Who is eligible for an additional shot of the COVID-19 vaccine?

Dr. Kessler began by explaining the difference between mRNA-based vaccines that require two shots, (Pfizer-BioNTech and Moderna) and adenovector virus vaccines, that require one shot (Johnson & Johnson). These vaccines were initially approved on an emergency use basis by the U.S. Food and Drug Administration (FDA) for use to prevent COVID-19, which is the illness caused by the SARS-COV-2 virus. The Pfizer-BioNTech vaccine, now marketed as Comirnaty, recently received full FDA approval for ages 16 and up.

People who are moderately to severely immunocompromised would benefit from getting a third dose of either one of the two mRNA vaccines (Pfizer and Moderna), according to updated guidance from the FDA. There is no guidance yet for those who received the Johnson & Johnson vaccine, Dr. Kessler said.

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What does it mean for a person to be “immunocompromised” and why is it necessary for them to get an additional shot?

Dr. Kessler said the term “immunocompromised” covers a wide spectrum of conditions and illnesses. But there are specific groups who would benefit from a third dose of the COVID-19 vaccine.

Those groups include but are not limited to: people with compromised immune systems; individuals who have received a bone marrow transplant or an organ transplant; cancer patients; people with rheumatoid arthritis or lupus who are taking medication that weakens or suppresses the immune system; patients who have lost their spleen; those with severe diabetes; people with HIV; and older people.

“We know, from the science that has been conducted on these individuals, that a fair proportion of them do not respond well to the initial dose of two vaccines, which the majority of folks have received.”

Immunocompromised people can build a more potent immune response with a third dose of the vaccine, Dr. Kessler stated.

Learn more about the eligibility criteria and schedule your third dose appointment >

When will the rest of the population be eligible for an additional shot?

The FDA and the Centers for Disease Control and Prevention (CDC) are studying vaccine effectiveness and immunity for non-immunocompromised people to determine if a third dose is necessary. Dr. Kessler said that the vaccination has been “remarkably effective” in preventing severe cases of COVID-19.

He said it was important to understand that while people who are vaccinated can still be infected by COVID-19 and can be asymptomatic or mildly symptomatic, the vaccination prevents severe outcomes in the vast majority of cases.

“The two doses of vaccine that most people have received continue to perform very well in preventing those most severe outcomes.”

Are there breakthrough cases of COVID-19 for some vaccinated people?

Although no vaccine is 100% effective, Dr. Kessler noted that breakthrough cases are very rare. The vast majority of severe cases of COVID-19 occur in individuals who have not been vaccinated.

“While there still remains a risk to an individual if they've been vaccinated, the risk overall is much, much less for getting infected and the risk is certainly a whole lot less of getting such a severe infection that you wind up getting hospitalized or dying,” he said.

What are COVID-19 variants?

Dr. Kessler explained that viruses have genetic material, and like any other living creature that reproduces, the genetic material must be replicated. The process of that replication is error-prone and creates mutations. Those mutations, ultimately, create new variants. Some of the variants are more fit than others and can potentially make the virus better able to infect and hurt its host.

He added, “Fortunately, most of those mutations are either meaningless, have no impact, or they're detrimental to the virus and the virus can no longer reproduce effectively. But, every so often, you'll get one that actually changes the virus in a way that makes it potentially more infectious or more dangerous.”

Can we prevent variants from occurring?

The way to reduce the number of variants is to reduce the amount of viral infection and replication that occurs in the community at large. The most effective means of reducing infection is vaccination, along with social distancing, masking and hand-washing. Dr. Kessler said, “If we can't get exposed, we can't get infected, and if we can't get infected, the virus can't replicate.”

If a third dose of the COVID-19 is eventually recommended, can a person receive that shot along with the seasonal flu vaccine?

Dr. Kessler said that, if the FDA approves a booster shot for COVID-19 for the general population, there will likely be an overlap with the flu vaccine. “We have to wait and see if there's any evidence to suggest there would be any problem about administering those two vaccines together but, up to this point, the COVID-19 vaccines that are available do not have any additional side effects when administered with other vaccines in close proximity. It’s likely to be safe.”

Why does it take so long for the FDA to give full approval to the COVID-19 vaccine?

The FDA has a standard process for how they evaluate vaccines to ensure they are safe and effective. Dr. Kessler said the process is rigorous and the FDA wants to make sure there are not a lot of potential side effects. The COVID-19 vaccines were granted emergency approval during the pandemic because the benefits of authorizing them were greater than the risks of delaying them. Dr. Kessler stated he believed that full approval of all three vaccines would occur by the end of 2021.

How has treatment of COVID-19 evolved over the past year?

Dr. Kessler said that a tremendous amount has been learned about how to care for patients suffering from COVID-19 and that has played a significant role in driving down the rate of severe illness and mortality from the disease. There are medications available for both mild cases and more severe cases of COVID-19 that require hospitalization. These interventions include the antiviral medications, steroid medications, and monoclonal antibodies.

Should immunocompromised people get a third dose of the same vaccine they received initially?

If the same version of the vaccine is available, it is recommended that individuals receive a third dose of that same version.

“If you had received Pfizer, if it's possible to get the Pfizer vaccine as the third dose, that's what should be administered. Similarly, if you had received two doses of the Moderna vaccine and it’s past a month from your second dose, if you’re severely immunocompromised, you should be vaccinated with the Moderna vaccine,” said Dr. Kessler.

However, if there are supply issues with one or the other vaccine, it is possible to mix the versions.

Can the vaccines be modified to keep up with the variants?

Dr. Kessler said that, in the future, it should be possible to modify the vaccine to account for new variants, especially using the mRNA technology.

He added “a little bit farther off into the future, (we can) potentially develop vaccines that would engender an effective immune response to a broad array of very similar viruses.”

What is the difference between a booster shot and a third dose of the vaccine?

A booster shot is for those who had strong immunity to the virus. A third dose is for those who are immunocompromised and have not developed an appropriate protective immune response.

In either case, the process will be the same when you go to the vaccine center, pharmacy or doctor’s office, Dr. Kessler said.

“You’re going to roll up your sleeve and they’re going to give you the same shot you got, whatever it was, three months ago, six months ago, whenever. From a practical standpoint, it's going to look the same, it’s going to feel the same, and you may have the same reaction, if you had a reaction to begin with, but there is a subtle difference.”

The difference is the immune response for the immunocompromised may be lower than in those who are not immunocompromised.

Learn more about COVID-19 vaccines and how to get one >