A doctor explains what people need to know about their immune system
A Pfizer-BioNTech COVID-19 vaccine shot is administered to a medical worker in December 2020 at Marian Regional Medical Center.
Dr. Bradley Allen
The author lives in Summerland
A doctor explains what people need to know about their immune system
Editor’s note: Dr. Bradley Allen is a pediatric heart surgeon and a Republican candidate for Congress in the 24th District, which includes Santa Barbara County.
Why are we still having problems with COVID-19? That’s the question on the minds of many Americans who wonder why infections remain high despite more than two-thirds of Americans having already been fully vaccinated.
COVID-19 vaccines have had a tremendous impact on preventing serious illness allowing a semblance of normality to return. But it is obvious that they are not the panacea we were led to believe. So understandably, questions arise as surely as viruses themselves mutate.
The answers can be found in a better lay education of our immune systems, which, thanks to the one-size-fits-all vaccine approach that’s generally been imposed by the CDC and federal government, has been ignored. A working understanding of immunity would allow Americans to make better healthcare choices and empower them to deal rationally with a disease that is likely to be with us, in one form or the other, the rest of our lives.
The good news is that all current COVID-19 vaccines give you internal immunity, which protects your major organs. By injecting the vaccine into your muscle, your body generates blood-circulating antibodies (Immunoglobulin-G, IgG), as well as memory and cellular immunity that protects your internal organs from severe infection.
The bad news, however, is that vaccines do not offer mucosal immunity, which is how the COVID-19 virus enters your body. Mucosal cells line the surface of many tissues including your mouth, nose, throat and breathing tubes.
These cells are protected by a particular form of a different antibody (Immunoglobulin-A, IgA), and a vaccine delivered into your muscle does not stimulate their production.
These IgA antibodies only develop if you are infected with the actual virus, or if a vaccine is delivered directly to the mucosa, as is done with the polio vaccine.
So even with multiple boosters, your mucosa is still vulnerable to infection, which is why most people will still get sick with COVID-19. The good news is that these infections typically result in only a cold or cough, since your internal immunity protects your major organs. Essentially, vaccines do what they were supposed to do all along: Protect you from serious illness.
The bad news is that your circulating blood antibody levels slowly decline after every vaccine or infection. Otherwise, we would have so many antibodies, our blood would be as thick as mud.
The good news is that COVID-19 vaccines also induce the formation of memory cells, called B-cells, that retain the ability to manufacture these antibodies whenever we are ever exposed to the virus.
Antibodies work by sticking to precise proteins on the surfaces of viruses and bacteria in a way specific to each type of virus. So, if a virus mutates (e.g., delta and omicron), the antibodies may be less effective because those antibodies won’t be modified toward the newer variants. This is one problem with the current boosters, they only produce the antibodies to the original virus.
Yet there’s more good news: Our memory B-cells can actually produce antibodies adapted against the covid variants they might see in the future, making these new antibodies more effective as the virus mutates. This is because memory B-cells serve as a blueprint for antibodies. This means they can, like architects, make simple adjustments to the original plan, modifying the antibodies. This means that memory antibodies may have greater potency against variants than antibodies elicited by vaccination or booster.
And even if the virus begins to evade our antibodies, vaccines (or natural infection) also generate cellular immunity through our T-cells that attack the pathogen directly. Think of the virus’ spike protein as being composed of many individual units (antigens). While antibodies attack the entire spike protein, T-cells attack each unit separately.
And even if the variants have mutations on the spike proteins where those T cells may not work, there are still many sites remaining for T-cells to protect your body against severe disease.
Now the exact number of T-cell antigens (epitopes) on the spike protein is currently unknown.
One study showed 1,400 across the whole virus, and another showed that there were 87 epitopes on the spike protein to which T cells respond. Importantly, the virus cannot mutate its spike proteins indefinitely and still retain its ability to function, as it’s the spike proteins that allow the virus to enter our cells. This is why it is doubtful a variant will be created that can evade our T cells.
Indeed, despite omicron’s extensive mutations and reduced susceptibility to antibodies, the majority of T cells still recognize the variant. So T cells are likely responsible for the vaccine’s amazing ability to protect us against severe disease.
So the good news is that with circulating antibodies, memory B-cells, and T-cells already present after a vaccination or natural infection, our immune system has the ability to stop an infection from taking hold the next time a person is exposed to the same virus.
The bad news is that if circulating antibodies are low, it can take several days for the memory B-cells to make new antibodies and for T-cells to be mobilized, leaving the person susceptible to a “so-called” breakthrough infection that, according to reports, is typically mild in people who aren’t otherwise high-risk.
Now, a booster may help by increasing circulating IgG antibodies.
Data from the United Kingdom’s Health Agency suggests that vaccine effectiveness in preventing symptomatic disease with omicron more than 25 weeks after vaccination with Pfizer was only 35% but rose to 75% with a booster. The bad news is that this booster protection may wane in 10 weeks, and as the virus mutates, a vaccine that produces the original antibodies will be less effective.
Even so, high-risk individuals (the immunocompromised, the elderly or those experiencing obesity, lung or heart disease, etc.) susceptible to severe reactions from even a mild infection should consider being boosted if they know they will be putting themselves in a high-risk environment, like being on a cruise ship.
But what about everyone else?
Here there is much good news. The greatest protection from hospitalization or severe disease remains heavily concentrated in the first two vaccine doses. A study from The BMJ found that despite waning ability to prevent mild infection from the delta variant, vaccine effectiveness against hospitalization in those who haven’t been boosted remains robust at 97.5%. In fact, in vaccinated people, the mortality can be higher for the flu than for COVID-19.
And according to the Centers for Disease Control and Prevention, as of Oct. 2, more than 146 million Americans have already had a COVID infection, a number which is certainly much higher now. When combined with the 78% who have been vaccinated, our collective immunity is now quite high, especially against severe disease.
Indeed, evidence suggests, that developing a COVID infection after being vaccinated may give superimmunity against future variants. Furthermore, we now have several therapeutic options to help minimize the weaknesses of vaccines, including an oral medication (Paxlovid) that reduces the risk of hospitalization by almost 90% in high-risk individuals.
By understanding how vaccines and our immune system work, Americans will be able to make educated healthcare decisions, and better determine how they want to move forward as a nation. And that is good news!
