Dr. Bryan Alsip talks about the new bivalent mRNA boosters that protect us against the latest COVID-19 Omicron subvariants BA.4 and BA.5.
He also discusses the complex human immune system and explains why he recommends stretching out the interval between the old monovalent boosters, or COVID-19 infection recovery, and getting the new shot.
What is the difference between the old mRNA COVID-19 boosters and the new ones?
The new shots are the first real updates that we've had to the COVID-19 vaccines since they were originally introduced in the later part of 2020. All of the vaccines that we've gotten up to this point, whether they were the primary series or booster doses, were the same type of vaccine. And that was built off the original strain of the SARS-CoV-2 virus.
The key difference between that vaccine and the most recent vaccines is that the new ones are what they call a bivalent vaccine, which means they have components of both the original strain of SARS-CoV-2 virus, as well as the Omicron subvariants that are known as BA.4 and BA.5.
Since those are the predominant strains that are circulating worldwide, particularly BA.5, it's felt that this newer vaccine will offer better protection and longer lasting immunity. And it's called a bivalent vaccine because it has those two components. One is the original strain and one is the new subvariants of Omicron.
I recently got the monovalent COVID-19 booster. Am I eligible for the new bivalent booster?
Yes, you're eligible for the bivalent booster. In fact, it is the only vaccine you should get as a booster dose, the monovalent vaccine is still available, but it really is only for individuals who have never had the COVID vaccine. So it will be the primary series that they should get as their first two doses.
How long should I wait after getting the old COVID-19 booster to get the new bivalent booster?
The FDA has authorized and the CDC has recommended that you wait at least two months after your most recent booster dose before you receive the bivalent vaccine.
I just got over COVID-19. If it was an Omicron subvariant, don't I already have protection against future Omicron infection?
Yes, you actually do have some protection. In fact we know from previous studies and with other variants of COVID that you have some natural immunity from a previous infection. That's one of the reasons why they recommend waiting for an interval of time before you receive a booster dose.
In this case, the CDC is recommending you wait at least three months at minimum between your recent COVID infection and receiving the bivalent vaccine.
How long should I wait after recovering from COVID-19 to get the new booster?
If you've recently had an infection, the CDC recommends you wait at least three months before you receive the bivalent vaccine booster. However, you could wait longer.
As with most vaccines, you'd never want to take a vaccine shorter than that interval or sooner than is recommended. But you can always take it later than is recommended. And in some cases, there may be some benefits to getting that booster at a later time.
Why is it better to stretch out the waiting period between vaccination or recovery and getting the new bivalent booster?
With many vaccines to include COVID, immunologic studies have shown if you extend that interval between doses, you can actually improve the immune response as well as the duration of protection. In some cases, extending that interval, in this case from two to three months to four to six months, may give you a longer lasting protection because it increases the number of neutralizing antibodies, which are the antibodies that actually target the pathogen in this case, the SARS-CoV-2 virus. It also increases the activity of B cells and T cells which are part of our immune system.
What are B cells and T cells, and how are they different from antibodies?
B cells and T cells are parts of our immune system. They are actually white blood cells.
B cells produce the antibodies that people know about. Antibodies are the ones that target those pathogens, whether it's bacteria, viruses or toxins.
T cells attack other cells that are infected with those pathogens. They're both part of our comprehensive immune system that helps protect us from disease.
What is hyperactive immunity?
Hyperactive immunity is a general term for an overactive immune state. And that can happen with certain diseases, but it also can happen with a normal response to either an infection or a normal response to a vaccination. It implies that there's a plateau, or a high level, of effectiveness of our immune system.
If you are in a hyperimmune state, there's probably limited benefit to getting another vaccine dose, it really doesn't add to the ability to respond more quickly, it doesn't provide a longer response.
However, if you come out of that hyperimmune state, which often happens with a longer interval between doses, that next booster dose really has a greater effect to enhance your immune system response, therefore give greater protection and could last longer as well in your system to protect you against disease.
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