How a vaccinated person can get a breakthrough COVID-19 infection
I thought the vaccines offered strong protection against the coronavirus. But now I’m hearing about vaccinated people getting sick. As a fully vaccinated person, how worried do I need to be about “breakthrough” infections of COVID-19?
Dr. McEver Prescribes
While the vaccines have proven highly effective against the virus, even for new variants like delta, they do not offer perfect protection. That is one of the reasons why the Centers for Disease Control and Prevention last week revised its guidance and recommended that in places with high rates of transmission such as Oklahoma, even vaccinated people should wear masks in public indoor settings.
The good news is that vaccines have been found to be extremely good at preventing serious illness and death. Of those hospitalized with the virus, more than 97% are unvaccinated. The CDC estimates that for every 102,000 vaccinated, only 100 end up hospitalized, and only one will die. While those numbers are not perfect — vaccines never are — they are very, very good.
If vaccinated people come down with infections, the vast majority will be asymptomatic or mild. Nonetheless, they may still be able to spread the virus to others before their immune system, which has been primed by the vaccine, stamps it out. Preliminary data suggest that when people do get breakthrough infections, they carry high amounts of the virus for at least a week.
As with the original strain of the coronavirus, dose seems to matter with the delta variant. The higher the load of viral exposure (think a brief masked encounter versus spending hours unmasked in a room with an infected person), the more likely immune defenses will become overwhelmed and result in a symptomatic or serious infection.
In science, we’re usually looking for breakthroughs. This represents one of the rare times we’re trying to avoid them. To do so, we all need to put our masks back on in certain indoor settings, at least until case numbers improve.
McEver, a physician-scientist, is vice president of research at the Oklahoma Medical Research Foundation. Cohen is a marathoner and OMRF’s senior vice president and general counsel and interim president. Submit your health questions for them to email@example.com.