With a recent rise of COVID-19 cases, the Delta variant and the return of certain restrictions, there is a lack of clarity in many people’s minds about breakthrough infections, vaccine efficacy, the pandemic’s trajectory and other issues. The Center for Disease Control and Prevention's (CDC) masking guidance update, driven by concern over breakthrough infections, is emblematic of this.
One of the biggest misunderstandings that persists is regarding rare breakthrough infections that occur and their importance. These rare events were always expected but perhaps poorly communicated, as no vaccine is 100 percent efficacious. Vaccines are not bug-zappers or “forcefields.”
What a vaccine does accomplish is remarkable: A vaccine primes the immune system to spring into action upon exposure to the virus and derail an infection before it has the chance to be as productive, to cause as many symptoms or to cause as much damage as it would have in the absence of this immunity. (Natural immunity also operates this way and is important.)
The early steps of the thwarted infection are what alert the immune system to the intruder, and the aftereffects of the incident are a boost to immunity. Vaccinated people are likely going through this process frequently, especially in places where COVID-19 prevalence is high. Sometimes, if testing occurs during the right window after exposure, with sensitive PCR tests, viral genetic material will be present in a high enough quantity for a test to be positive.
As most breakthrough infections do not result in symptoms, they cannot be classified as disease and are, to the individual involved, medically insignificant. However, a positive test, even if without clinical value, will be disruptive because it is a positive test.
While there are important scientific questions regarding symptom-less breakthroughs (including how frequently it occurs, which variants are present, how much virus was present, and time post-vaccination) from a clinical perspective there is no treatment.
In the extremely rare cases in which symptoms occur — true breakthrough disease — it is crucial to realize that were it not for the immunity that existed, things would have been worse. This is very apparent with influenza vaccines, which are very good at blunting the risk for hospitalization but do not stop all infections.
The fact is that mild breakthrough infections are a vaccine success — not a short-coming.
COVID-19 has become an endemic infection much like the other four coronaviruses that cause about 25 percent of common colds. Because it is an efficiently spreading respiratory virus with a wide spectrum of symptoms and animal hosts, we will not eliminate it. It is with us. This means that we will always have some baseline level of cases, hospitalizations and deaths with season-to-season variation. The goal is not to achieve some fantastical “COVID zero” status but to deny the virus the ability to cause serious disease, with hospitalization and death on a scale that could threaten hospital capacity.
In states where vaccination rates are high, the vaccines we have in the U.S. are performing tremendously. Vaccines are taming the virus by relegating to the status of other respiratory viruses we deal with year in and year out. This was largely achieved by vaccinating those at highest risk for hospitalization.
In the U.S., tens of thousands of cases of COVID-19 occur daily. These cases are being driven by unvaccinated people spreading the more fit Delta variant of the SARS-CoV-2 virus. It is no coincidence that the states with the highest cases are the states with the lowest vaccination rates. As CDC Director Dr. Rochelle WalenskyRochelle WalenskyFDA panel endorses COVID-19 booster shots for older Americans, rejects widespread use Watch live: White House COVID-19 response team holds briefing The Hill's Morning Report - Presented by National Industries for the Blind - Tight security for Capitol rally; Biden agenda slows MORE and President BidenJoe BidenHouse clears bill to provide veterans with cost-of-living adjustment On The Money — Dems dare GOP to vote for shutdown, default To reduce poverty, stop burdening the poor: What Joe Manchin gets wrong about the child tax credit MORE have both stated, we are now in a “pandemic of the unvaccinated.”
Attesting to the power of the available vaccines, virtually everyone hospitalized with COVID-19 currently is unvaccinated. This is true even in states with low vaccination numbers.
The uptake of the vaccine is not uniform, however, and in those regions with substantial and high spread, breakthrough infections will be more common because it will be more likely that one run into the virus in their daily life. It makes sense for immunocompromised individuals, for whom standard vaccination doses may not be sufficient, to be vigilant and wear masks in public indoor spaces.
However, it is unclear why the pandemic of the unvaccinated impacts the behavior of the healthy, fully vaccinated. The CDC cited unpublished case studies in which Delta variant breakthrough cases on “rare occasions” in “some vaccinated people may be contagious” but that vaccinated individuals account for a “very small amount of transmission.” These findings, which would be important to publish and have peer-reviewed, prompted the CDC to shift guidance for the fully vaccinated in areas in which substantial or high levels of COVID transmission are occurring.
If vaccinated individuals account for a “very small amount of transmission” when these “rare occasions” occur, is there going to be much impact from this guidance? I believe it will have little impact on case rates.
The virus treats a vaccinated person very differently than an unvaccinated or non-immune person and, therefore, others should treat them differently because they are not the same COVID-19 threat.
An endemic respiratory virus is something that most of us will eventually contract. Some of us have or will get it unvaccinated in its full form, others in a mostly innocuous vaccine breakthrough version.
If we are to concern ourselves perpetually with preventing rare or very small events from happening, seeking to achieve a state of zero risk — where we become overly concerned with preventing a small proportion of the fully vaccinated from experiencing minor cold-like illnesses — then this pandemic can have no off-ramp.
The aim should always have been to guard against hospital capacity concerns and deploy COVID-19 vaccines widely, in combination with natural immunity. Now, the focus must be in addressing the clusters of the high-risk unvaccinated individuals. Hopefully, with full Food and Drug Administration approval, with more businesses and organizations requiring a COVID-19 vaccine, and with persuasion from trusted community leaders and primary care physicians, vaccinations will rise, and the less effective substitute of masks will no longer be part of the discussion.