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Delta variant Q&A with UK HealthCare experts

John A. Bauer, Ph.D., and Sean McTigue, MD.
Blog

/ by UK HealthCare

With the delta variant of SARS-CoV-2 — the virus that causes COVID-19 — spreading rapidly, communities throughout the United States are facing tough decisions about how to deal with the evolving pandemic.

We recently spoke with two UK HealthCare experts about the efficacy of COVID vaccines and community mitigation efforts, new visitor restrictions in UK clinical settings, and more. 

Dr. Sean McTigue, medical director for Pediatric Infection Prevention and Control at Kentucky Children’s Hospital, and John A. Bauer, Ph.D., Vice Chair of Research, Department of Pediatrics, here address several questions surrounding the current state of the pandemic. 

What’s a breakthrough case? 

McTigue: A “breakthrough case” is defined as a new case of confirmed COVID infection in someone who was previously immunized. Currently, breakthrough cases are less common than second cases of COVID in unimmunized individuals.

Bauer: In general, people that have been immunized have had only low level 'breakthrough' and severe problems have been very rare. The risk of breakthrough illness is greater with the delta variant than other previous virus strains that were more common in the U.S. last year. 

The best way to avoid hospitalization or death from COVID is to be fully immunized. The FDA has recently approved an additional 'booster' dose of vaccine to persons who might not have a very capable immune system due to other conditions. 

Why the new visitor restrictions at UK HealthCare hospitals and clinics even if the hospital isn’t full? 

McTigue: We are seeing increasing numbers of COVID cases in the community; this means that visitors are increasingly likely to be infected when compared to times when less virus was circulating. We are also seeing increasing numbers of admissions for COVID and need to protect patients, visitors and staff to the best of our ability.

Bauer: Because it is possible for some persons to carry the virus but have minimal symptoms, we are concerned about spreading the virus to others. The best way to minimize the risk of spreading is to avoid having many people in crowded spaces. 

Other steps that are helpful include having all people wear masks so they do not spread the virus, and for everyone to get vaccinated so that they can reduce the virus's chance to spread from one person to another. 

Will I need a vaccine booster? 

McTigue: The FDA has recently authorized a booster for certain high-risk immunocompromised patients who are less likely to have responded to the initial series of two doses. It is too early to know if and when a booster will be needed for other patients. At this time, vaccines appear to be functioning well and offering protection.

Bauer: The currently available vaccines provide immunity against the delta variant and a person getting very sick from the virus after they are fully immunized is very rare. Booster vaccinations have been approved by the FDA for high-risk immunocompromised patients, and other groups may be included in the future. Other strains of the virus are also likely over time, so it is possible that booster treatments may be needed (similar to flu vaccinations, which are tailored each year to the strains that are circulating in that season).

Should I get the vaccine if I’m pregnant? 

McTigue: The ACOG (American College of Obstetricians and Gynecologists) is recommending that pregnant women be vaccinated, as they are proving to be at a greatly increased risk of severe illness from COVID.

Bauer: Last year and early in the pandemic it seemed that COVID was not a large concern for pregnant women or their babies, but more recently the CDC and ACOG have raised their recommendations to encourage vaccination for this group. Pregnant women are now recognized as having increased risk of severe illness, to both the mother and to the fetus/infant. This change to increased concern is apparently related to the delta variant of the SARS-Cov-2 virus being more rapid in its growth and it being more difficult for a pregnant woman to defend against due to reduced immune function that typically occurs during pregnancy. 

When will vaccines for kids under 12 be approved? 

McTigue: Only the FDA can answer this question, but approval of the Pfizer vaccine for younger patients seems likely to be granted sometime this fall. 

Bauer: Many families are asking this question and hopefully the FDA will have more answers soon. The process for vaccine approval includes several steps, including finding an optimal dose, determining side effects and toxicities, and identifying a strategy that provides a consistent immune response that can provide protection from an exposure to the real virus later on. The process is rigorous and takes time and many thousand study participants. It appears that the product developed by Pfizer, and perhaps others, could be approved before the end of the year. Other products are also not far behind in the timeline.

Why do masks work? What’s the point? 

McTigue: Masks seem to work better at preventing transmission when worn by an infected person because they limit the distribution of infectious material by blocking droplets and keeping expired material from being expelled farther out towards others. They can also prevent droplets from entering the mouth and nose.

Bauer: Containing exhaled breath droplets from an infected person, and decreasing the inhalation of those droplets are the most important elements of mask-wearing. 

The virus can also be transmitted by touching surfaces and contact by mouth or eyes, but these seem to be less prevalent methods of transmission. Inhalation seems to be the main way this virus is spread. This is especially true for the delta variant, which is 2-3 times more contagious than the strains that were circulating last year when the pandemic started. 

I’m fully vaccinated and most likely won’t get sick or hospitalized. Why should I care about the delta variant? 

McTigue: While being immunized greatly reduces the likelihood of severe illness including hospitalization, the risk is not zero. The delta variant appears to be far more infectious than prior strains. 

Bauer: An important element of vaccination against a virus is that it stops the spread of the virus amongst people, but it also slows down the replication of the virus (since it’s not growing as fast in many people) and decreases the risk of having the virus mutate to other strains that might be more harmful. 

The delta variant is part of a typical viral process of changing over time as it reproduces. In this specific case, the delta variant apparently is more efficient at reproducing and grows faster. This helps the spread of the virus since a person has a 'higher viral load' faster and can be more contagious.

I’m fully vaccinated but over 65. Should I be worried? 

McTigue: Being fully immunized offers the best available protection from severe illness, hospitalization and death. While there is still risk, the risk is much higher for those who are not immunized.

Bauer: At this time, booster shots have not been recommended or approved by the FDA for groups other than immunocompromised persons. This may change in future months.

I’m fully vaccinated but immunocompromised. Should I be worried? 

McTigue: Immunocompromised individuals should check with their physician to see if they fall into a group for whom a booster is now recommended and authorized by the FDA.

Bauer: The recent recommendation by the FDA would be to see your physician and discuss if you are an appropriate candidate for a booster.

I’m fully vaccinated but pregnant. Should I be worried? 

McTigue: Pregnant women are at far greater risk of severe illness, hospitalization and ICU admission, and therefore should be immunized, as this will greatly decrease the risk of these serious outcomes.

Bauer: Being immunized will reduce your risks of serious illness if you come in contact with COVID-positive persons. It still would be entirely appropriate for you to wear a mask when you are around others, to do your utmost to protect yourself. 

How does an mRNA vaccine work? 

McTigue: mRNA is a molecule that is used by the body as a template to produce a protein and then is rapidly broken down. The mRNA vaccine works by having a number of cells take up mRNA that causes them to make the spike protein of SARS CoV2 (the virus that causes COVID-19). The immune system then responds to these spike proteins as if those cells were infected with the virus and learns how to respond to the virus in a way that produces antibodies and teaches t-cells how to recognize the virus in the future.  

Just like the mRNA produced by your own body when making its own proteins, the mRNA from the vaccine is very rapidly broken down and eliminated. This allows for the very robust response that is typically seen in a “live virus vaccine” without ever exposing the patient to any virus at all.

Bauer: Cells use mRNA to make proteins. In the vaccine product is a specific mRNA that briefly stimulates cells to make a protein that is typically found on the surface of the SARS-Cov-2 virus particle (the ‘spike protein’). Then the person's immune system recognizes this protein as ‘not-appropriate’ and develops antibodies against it. That way the person then has immunity against that protein, and therefore can attack and kill the virus particle when exposed to it later on. 

This mRNA strategy developed for vaccines is a major breakthrough for human health and it has been shown to be very safe, and in some cases safer than other older technologies for vaccination. One advantage is that other specific mRNA codes can be used, and can be developed for other treatments against other viruses, or even specific cancers. 

How do adults getting vaccinated help protect kids? 

McTigue: By immunizing as many eligible people as possible, this will greatly decrease the likelihood of a child who is not old enough to qualify for immunization of coming into contact with someone who is infected and contagious. This is known as herd immunity.

Bauer: The best way to protect children from getting very sick from the virus is to not have them exposed to it. Since there are no vaccines yet approved for children, the current best way to reduce virus exposure for children is to get all eligible people vaccinated, especially adults who may come in contact with children, and to wear masks to decrease the spread of the virus in areas that children and other unvaccinated people could be exposed. In general, these are the same approaches that public health professionals have for other contagious and life-threatening viruses. The SARS-Cov-2 virus is very contagious, more than twice as spreadable than flu virus. It also can cause major illness in some children for reasons we do not yet understand, and our children's hospital has been increasingly caring for very sick COVID-positive children in our ICU. We therefore encourage parents and families to follow the guidelines from the American Association of Pediatrics and get vaccinated and mask up. 

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