Distinguishing Egg-Based Vs Cell-Based Vaccines


Distinctions between vaccine types are explored, as well as considerations such as egg-based allergies.

Mitchel Rothholz, RPh, MBA: There are different versions of the flu vaccine available this season, whether it’s adjuvant, quadrivalent primarily this year, or trivalent in the past. There was a period where we had both trivalent and quadrivalent available at the same time. Then we’ve got recombinant and egg based. Randy, could you give our audience some perspective of some of the differences between the different vaccines and how to best manage them within their practice?

Randy McDonough, PharmD, MS, BCGP, BCPS, FAPhA: I appreciate that question, Mitch, because we get questions from patients. As patients ask me about the different vaccines, I say the egg-based vaccines are the ones that have been around. There’s a long history. We have extensive experience in large-scale production and being able to streamline that production and automation of a highly standardized process. Plus, we’ve got extensive safety data.

The challenge with using egg-based, obviously, is patients who have true egg allergies. It’s a very labor-intensive technology. There’s a length of time to produce. When we look at what happened with the COVID-19 pandemic, with egg-based technology, we wouldn’t be able to get vaccine out as fast as we did. There’s a potential interruption of supply, plus there’s a possibility that viruses can mutate, so the vaccine may not be as effective as it needs to be.

As we look at recombinant DNA, what’s nice about that from a benefit is we aren’t dependent on egg supply anymore. The manufacturing process could be much faster. During a pandemic, as we saw with COVID-19, we were able to produce large volumes of the vaccine in a relatively short time. It also avoids the mutations that occur. Plus, we’ve seen that people may have a greater antibody response, especially older patients.

The challenge with recombinant DNA, as far as the limitation, is that it’s approved for patients 18 years of age and older. It’s a newer technology, so there’s a lot of misunderstanding and misperceptions about how it’s made, what it’s going to do, and how it works in your body. Cell based is the same thing with the same type of benefits. It’s manufactured in a different way so you don’t worry about the egg allergies anymore. Make sure people understand that it’s a newer technology. If there are any misunderstandings, misperceptions, or myths about what this can do in your body, then we have to address that with patients.

I’ll also address that it isn’t just the difference in the flu vaccines. We have to make sure we’re careful about how we store them and which ones we’re picking out. If we’re dealing with children, make sure we aren’t giving them a vaccine that hasn’t been approved for the age group. It’s very complicated compared with a COVID-19 vaccination program for children. To minimize any errors, not only in the storage but also in the administration, we’ve scheduled certain times of the day when we do certain age groups. That way, only that particular age group, vial, or color code is out, and we minimize any type of error that could occur. We’ve done a lot of work to minimize and avoid errors within the pediatric population.

Mitchel Rothholz, RPh, MBA: Randy, you talked about the pediatric population, and we talked earlier about the timing of when somebody should get their vaccine. We recommend it later in the season. But with the pediatric vaccine, especially a naïve child, what’s the recommendation? Is it OK to start earlier in the season? Do those individuals have to get more than 1 vaccine? Give a little insight into that.

Randy McDonough, PharmD, MS, BCGP, BCPS, FAPhA: Yes, with those pediatric patients, with anyone who’s 9 years of age or younger, we have to be cognizant that if they’re vaccine naïve, especially as we talk about influenza vaccine, they will need 2 shots at least 4 weeks apart. It doesn’t even have to be within the same season. If they’ve had 2 shots over 2 subsequent seasons, then for their next shot, they’ll be eligible for just the 1 shot. It’s more important that we get that started for the child and then get them that second shot to get them the full protection for that season.

Mitchel Rothholz, RPh, MBA: Thanks, Randy. Any additional insights from our panel?

John Beckner, RPh: When you get into the different types of vaccines, there are operational considerations with regard to inventory. Depending on the pharmacy and their ability to handle the carrying costs for that inventory, there may be some reluctance to carry every single vaccine. There are some operational considerations that come into play.

Jeff Goad, PharmD, MPH: Absolutely. I was going to add a little to what Randy was saying. Some of the other reported advantages of our non-egg-cell or egg-based vaccines was that you could make them faster if we had a drifted strain and we got word to the manufacturers. We haven’t done that, but the potential is still there for them to reconfigure the vaccine and produce it faster than the egg-based technology, which takes quite a bit longer to do.

The other challenge we’ve seen lately is egg adaptation, where the egg-based vaccines have to grow in a hen egg. They have to learn to live in that environment. Sometimes it changes their immunogenicity, and their ability to create the immune response in humans doesn’t do the same as what we thought it did when we tested the egg. The challenge is that egg-based technology is susceptible to egg adaptation, which can change its ability to work well, whereas the recombinant or cell-based vaccines don’t have that. There are trade-offs. I definitely agree with Randy. We should also consider the long history of egg-based vaccines. But there are some advantages as we learn more about the non-egg-based vaccine.

Randy McDonough, PharmD, MS, BCGP, BCPS, FAPhA: Getting back to what John talked about, we’ll be ordering every type of vaccine. We hadn’t really ordered the cell-based [vaccine] this year. But we started talking about whether there could be a patient who would benefit from it, especially if there’s an egg allergy or if they’re younger. The recombinant vaccine isn’t going to be for that younger patient. Can we give them a cell-based [vaccine]? It’s a safer alternative. We have to think about this from a patient’s perspective: who will benefit from that vaccine? How much do I carry? Then you could start making better decisions about the inventory.

Mitchel Rothholz, RPh, MBA: Great perspectives, gentlemen.

Transcript edited for clarity.

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