Understanding Why Breakthrough Covid Occurs

This article (MedPage Today) popped up in my In-Box and I believe it is a good average – person on the street (high school education?) read if you want to understand “why,” why getting vaccinated is not a failsafe solution. You still have to socially distance, stay out of bars even if the owner is an ass, wear facemasks amongst other people, etc. so as not to catch Covid.

The article explains why you should be vaccinated even if the vaccine is not the 100% impenetrable Covid – proof – jacket many people believe it should be. Checkout the multiple comments made by doctors, nurses, etc. too in the comments section. This article was well-received by medical personnel.


We Can All Benefit From Helping Patients Understand Breakthrough COVID | MedPage Today, Gary C. Steven, MD, PhD August 27, 2021


Why am I posting this commentary???

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. Understandably people are 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 (the doctors (not me) can help patients (us) understand this by using three talking points:

(This follows what I [the blog author] know to date and is difficult for me to explain. I am hoping to clear up some misunderstanding by quoting the doctors version of this which I am sure Joel and also Daniel Becker would agree on it.)

Three Points of why we should still mask up, socially distance ourselves, etc.

  • The antibody levels in the bloodstream gained from vaccination are completely helpless at  preventing infection.

Simply, vaccination is not a guarantee to prevention. Vaccination neutralizes virus particles from the environment which is the result of the vaccine-induced antibodies in our respiratory, GI, and ocular secretions. Or our “frontline” defensive antibodies in our saliva, tears, nasal secretions, and pulmonary mucus.

When exposed to airborne virus particles, 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. This is all we have.

If we are exposed to so many virus particles that all the antibodies in these secretions have attached themselves to virus particles and we continue to be exposed to new particles in greater numbers than we can transport more antibodies into these secretions; our antibody defense becomes overwhelmed when we inhale or come in contact with more virus particles than we are able to neutralize. The end result is becoming infected.

  • Circulating antibodies help to contain the infection

The vaccine introduces antibodies to help contain Covid. Once infected, the virus takes over the machinery of our cells to make more virus particles and release them. The circulating vaccine-induced antibodies latch on to these newly minted particles preventing them from infecting adjacent cells and from being exhaled.

One of the Delta variant’s strong suits from the beginning is Covid -19’s ability to reproduce itself so rapidly our antibodies are overwhelmed and do not slow it down much. Ultimately, infected vaccinated people shed virus similarly to unvaccinated folks.

  • Our vaccine-induced T-cell immunity limits disease severity

The third element of the response to the vaccine is the induced T-cell immunity. Our immune system kills off infected cells which are a lost to Covid and will need to be replaced. This limits the extent of disease. (To my limited knowledge, pre-vaccine T-cells would over react and flood the lungs).

Vaccines are effective at limiting the severity of disease, and is the reason why we do not see many vaccinated people among the hospitalized even as the number of vaccinated people infected with the Delta variant increases. This is also why it is critical to get vaccinated. The vaccines are extremely effective at preventing severe illness and death from COVID-19.

It is not in the T-cell job description to prevent viruses. Vaccine-induced T-cells do not provide protection against getting infected. They only mitigate severity once infected.


More and more vaccinated people are getting infected because they are interpreting vaccination as a carte blanche to return to pre-pandemic life without restriction. They (we) are exposing ourselves to massive viral loads overwhelming the immunity gained from vaccination.

We still need to practice social distancing and masking after vaccination to minimize and/or prevent infection even after vaccination.