Colin Powell has died; that is sad. He apparently died from complications of COVID-19 after having been fully vaccinated; that’s sad, but not unexpected. News reporters who are antivaxxers have been quick to jump on this death as one more example of “vaccine breakthrough,” a facile term for cases of COVID-19 in fully vaccinated people, as proof that the available vaccines don’t work and are unnecessary.
By announcing breakthrough infections as if they are unexpected and represent vaccine failure, we are doing our COVID-19 vaccines and the public a huge disservice. In fact, the current U.S. vaccines are doing exactly what they were intended to do, and doing it remarkably well.
As an infectious-diseases specialist and virologist, I would like to put the so-called breakthroughs in scientific context.
First, they simply reflect the known capabilities of the vaccine. We all were delighted last year that the efficacy shown in phase 3 studies was in the range of 90%. While that level of protection is cause for celebration, it means that 10% of vaccinated individuals were not fully protected against infection. Given that at least 200 million Americans have now been vaccinated, we could expect 20 million postvaccination SARS-CoV-2 infections—a number far in excess of the reported “breakthroughs.” So counting vaccine failures as “breakthroughs” actually means that we are double-counting the clearly recognized percentage of original study patients who were not protected.
Second, we need to understand the nature of the postvaccination COVID-19 cases we are seeing. The reasons people can and do get infected after vaccination are manifold and include patient-centered issues such as advanced age, underlying diseases such as cancer (which General Powell had), rheumatological/inflammatory diseases, and the many treatments for these illnesses that frequently suppress immunity. Therefore, many if not most postvaccine infections may occur in people who never had any immunity in the first place. Then there are virus-based issues such as mutation leading to the emergence of variants, for which the vaccines were not developed and tested. This latter issue has become common with the SARS-CoV-2 virus, but exists for many other viruses, including the influenza virus. The emergence of influenza virus variants through mutation—known as antigenic drift—is one of the main reasons we have to get flu shots every year. Fortunately, in immunocompromised individuals, most postvaccination infections are mild or asymptomatic, but they can be as severe as they are in the unvaccinated.
Finally, and perhaps most important: are asymptomatic postvaccination cases contagious?
We do not know the answer yet for certain. We know that these patients have “positive PCR tests” for COVID-19, which signify viral nucleic acid in their nasopharynges. But significantly, PCR testing does not tell us if infectious virus is present. We also know that positive PCR tests for COVID-19 have been recorded long after people are no longer sick. This holds true for other respiratory viruses as well. Children vaccinated with vaccines that use live, weakened viruses to induce immunity—the measles vaccine is one of these—can harbor weakened measles virus in their throats for long periods of time. This phenomenon does not negate vaccine efficacy; in fact, it might enhance it. None of the highly efficacious vaccines we use today is 100% effective. This means that some postvaccination positivity is probably a known second chapter for all of them. The term postvaccination positivity is far less catchy than breakthrough, but it describes the science behind the headlines in a considerably more accurate way.
While the primary goal of a vaccine is to prevent infections, equally important goals are to prevent symptomatic infections, prevent hospitalization, prevent the need for intensive care, and prevent infection-related deaths. In all these latter categories the COVID-19 vaccines have been exceptionally effective. Unfortunately, they were not in General Powell’s case.
The bottom line: this is a “glass 90% full” situation and it would behoove us to not accentuate the glass that is 10% empty. This mistaken emphasis is clearly one of the reasons that so many Americans are avoiding vaccination—“It doesn’t work, so why bother?” Comparisons of the rates of newly spiking cases, hospitalizations, and deaths in undervaccinated states with those in highly vaccinated ones in the United States are proof positive of vaccine efficacy. Further, the recently described benefits of receiving a booster shot should not diminish confidence in these vaccines. In fact, a second flu shot has long been recommended in prolonged flu seasons. The Food and Drug Administration has just approved complete authorization of the Pfizer vaccine. Full approval of the other COVID-19 vaccines is sure to follow soon, and every means available should be brought to bear to achieve the goal of getting all adults and children vaccinated.
