By Rachel Sawicki

The omicron variant was first identified in the United States on Dec. 1 and has now been detected in most states and territories, according to the Centers for Disease Control and Protection.

Two vaccine doses may not be enough to adequately protect people from the most transmissible variant yet, especially several months after the date of one’s second dose. That is why the CDC is recommending everyone ages 18 years and older get a booster shot at least two months after their initial Johnson & Johnson/Janssen vaccine or six months after completing their primary COVID-19 vaccination series of Pfizer-BioNTech or Moderna.

It is important to note that there is a difference between a booster and an additional dose, originally called a “third dose,” which is given to people with moderately to severely compromised immune systems. The CDC recommends an additional dose at least 28 days after the second dose of Pfizer or Moderna, or two months after the first dose of J&J/Janssen.

In Delaware, approximately 63.5% of the population is fully vaccinated and 31.2% of the fully vaccinated population has received a booster, according to a press briefing on Tuesday.

“We’re making some progress there but we’d like to be further along, particularly in the older group which has been eligible for a longer period of time,” Gov. John Carney said at the press conference.

The Delaware State News talked to Dr. Stephen Eppes, associate infection prevention officer and vice chair of the Department of Pediatrics at ChristianaCare, to answer some questions about booster shots, which he said will be extremely important in controlling the predicted surge in COVID-19 cases as the omicron variant spreads.

Q: How much does a booster shot “boost” one’s immunity?

A: I think we can answer this in several different ways. It is called a “boost” for a reason and almost all vaccines that were given to both children and adults are given as a primary series followed by a booster, meaning to boost the immune response to the antigen in the shot. So first, we can measure that in antibodies, which are proteins that are made by your immune system. We know that the antibody level is boosted at least tenfold after the (booster), compared with just the first two in the primary series. Then there is a part of the immune system that involves T lymphocytes (also called T cells), which are white blood cells in the immune system that are extremely important in our immune response and can actually provide long-lasting memory so that people may still be immune, even if the antibody level starts to decline. And then a third way we can show that a booster boosts your immunity is by the actual protection against the disease.

Q: What are some studies that show the actual protection against the disease?

A: One example is an Israeli study published in the New England Journal of Medicine (“Protection of BNT162b2 Vaccine Booster against Covid-19 in Israel”), where they took adults aged 60 years or older and formed two groups. One group had just had their two mRNA vaccines, the other had two mRNA vaccines and a booster. The booster group had 11-fold less infection and 20-fold less severe disease. So boosters clearly work and those are the lines of evidence.

Q: Are people who have only had the first two doses still protected?

A: So the first two doses did a really good job at protecting against the original SARS-CoV-2 and did a pretty good job at protecting against delta, which we’ve had in the United States for the better part of six months. Unfortunately, two doses don’t provide very good protection against omicron, and that’s the variant that is spreading across the nation and across the world as we speak. And to get that protection against the omicron variant, you really have to have that booster dose. There is the phenomenon of waning immunity, that is for sure. But getting that really high level of antibodies and that all-important T cell response is what seems to be the key to protection against the omicron variant.

Q: Is there any indication that people will start needing a booster every six months to a year, especially should more variants surface?

A: I think the answer is “probably.” We are going to be coexisting with COVID for a very long time to come and I’m not the one to predict whether that is going to be six months, a year or many years. But there are several reasons for getting additional shots. One is the boosting phenomenon. Another is if we see strains or variants developed that aren’t well protected by the original shots. So a familiar example is the flu. The flu vaccine changes at least a little bit almost every year to keep up with the mutations or the changes in the influenza virus. And there are a lot of experts that believe that COVID will behave in a somewhat similar fashion.

Q: Are the booster shots a different formula than the original first two doses?

A: No. Using the same vaccine we’ve used for exactly a year seems to provide good protection against the omicron variant. However, Moderna is actually gearing up to develop an mRNA vaccine specific to the omicron variant. It is too early to predict exactly where this is going to go, but I think it is likely that (changes in the vaccine) will be necessary depending on the behavior of this virus.

Q: How are herd immunity levels going to be affected? Will it now have to be measured by how many people have a booster shot?

A: There are so many moving parts to herd immunity. There is some protection conferred by natural immunity from having an infection, which nearly a quarter to a third of the population has probably had a natural infection. But the herd protection against delta is going to be different from what it is against omicron because it is so much more transmissible. People who have two doses probably don’t have greater protection against omicron, maybe a little, than those who have a booster. The other thing that determines how well we do as a population is how well people practice other mitigation strategies.

Q: How is the situation becoming more dangerous for people who are unvaccinated altogether? What are the additional risks they face that are posed by new variants?

A: Among the unvaccinated, omicron is likely to spread very rapidly, which is why we are anticipating a wintertime surge. We have to worry about these people because they can be hospitalized and they can die and they are much more likely to suffer a bad outcome than people who have some protection as far as vaccines go. Another thing that deserves mention is that the people who are unvaccinated, even if they don’t get that sick, can turn around and spread it to others who have gotten vaccinated, especially the people who have only had two shots. Some of those people are going to get sick. They probably aren’t going to get as sick and they’re probably not going to die, but that is another population we really have to worry about that will contribute to the overall surge that we are anticipating.