— Here’s how to approach the conversation
by Gary C. Steven, MD, PhD
The recent change in masking guidance from the CDC and reinstated public health measures from local and state governments have been met with frustration and defiance, with people understandably questioning why they got vaccinated if they have to go back to masking and distancing anyway. The answer is in the degree of exposure to SARS-CoV-2, and the explanation lies in the way vaccines work. We can help our patients understand this with three talking points:
- The antibody levels in the bloodstream are completely helpless at preventing infection (saying it that way seems to get everybody’s attention!)
Neutralizing virus particles from the environment is the sole responsibility of the vaccine-induced antibodies in our respiratory, GI, and ocular secretions — our “frontline” defensive antibodies in our saliva, tears, nasal secretions, and pulmonary mucus. When exposed to airborne virus particles, these antibodies attach to the spike protein of SARS-CoV-2, physically preventing it from latching on to the ACE2 receptor on the surface of our respiratory epithelium and gaining entry to those cells to cause an infection. But that’s all we’ve got — if we are exposed to so many virus particles that all the antibodies in these secretions have attached themselves to virus particles, yet we continue to expose ourselves to new particles faster than we transport more antibodies into these secretions, our antibody defense gets overwhelmed, we inhale or come in contact with more virus particles than we are able to neutralize, and we get infected.
- Circulating antibodies help to contain the infection
Once infected, the virus takes over the machinery of our cells to make more virus particles and release them, and that’s where our circulating vaccine-induced antibodies come in. They latch on to these newly minted particles to prevent them from infecting adjacent cells and from being exhaled. Therein, unfortunately, lies one of the Delta variant’s strong suits — it can reproduce itself so rapidly that our antibodies don’t slow it down much, and we see that when infected, vaccinated people are shedding virus similarly to unvaccinated folks.
- Our vaccine-induced T-cell immunity limits disease severity
The third element of the response to the vaccine that you don’t hear as much about is the T-cell immunity that is induced. This arm of the immune system kills off our own infected cells — they’re a lost cause anyway, and will need to be replaced — and thereby limits the extent of disease. That’s why the vaccines remain effective at limiting the severity of disease, and the reason why we don’t see many vaccinated people among the hospitalized even as the number of vaccinated people infected with the Delta variant increases. That’s also why it’s so critical to get vaccinated — the vaccines are extremely effective at preventing severe illness and death from COVID-19. But it is not in the T-cell job description to go after viruses themselves. Vaccine-induced T-cells do not provide protection against getting infected; they only mitigate severity once infected.
So, the CDC revised its masking guidance because, as we’re seeing in places like Provincetown and Milwaukee’s Deer District, vaccinated people can both get and spread SARS-CoV-2. More and more vaccinated people are getting infected because they’re interpreting vaccination as carte blanche to return to pre-pandemic life without restriction and are exposing themselves to massive viral loads that overwhelm their immunity. Every single vaccinated person I spoke with during a telemedicine visit in July who got themselves infected at a Bucks championship game told me they would have taken more precautions had the meaning of vaccination been explained to them as I have above.
These principles add to the arguments surrounding whether to administer a third dose, as recently discussed. Many studies have shown that neutralizing antibody titers decline only slowly over months, while we continue to see blunted disease severity in those vaccinated individuals who get infected. Moreover, breakthrough infections are not only occurring in older people who are far out from their second dose. This suggests breakthrough infections may occur not so much because of waning immunity, but because of people’s behavior that exposes them to overwhelming viral loads, especially in the face of the new variants. If that’s the case, a third dose without behavior modification may not be enough to promote sufficient disease containment. We need data from our contact tracers on the circumstances under which breakthrough infections occurred to better inform the decision on a third dose.
I believe history will judge our response to the pandemic harshly for its reliance on mandates more than education. We physicians were not consulted appropriately early on in the pandemic for our expertise and community respect to help shape local and regional procedures tailored to maximize disease containment while mitigating economic impact. There remains no coordinated effort to promote local physician involvement in mitigation strategies, and we are seeing the fallout from that in the current surge. So we must take it upon ourselves to do everything we can to educate our patients by promoting evidence-based containment measures and offering common-sense explanations for COVID-19 and the vaccines.
This is the most important public health crisis of our careers and lifetimes, and the urgency of this situation will reach a whole new level if post-acute COVID syndrome (PACS) turns out to be a virus-triggered autoimmune response that intensifies with subsequent infections. I sure hope that will not be the case and there is no evidence for that yet, but we physicians don’t have the luxury of waiting to find out. We need to leverage the respect we’ve earned among our communities to do what we can to transcend the rhetoric and misinformation, and minimize the worsening catastrophe that we know COVID-19 can become. Now.