Q: What is the risk of COVID-19 infection after being fully vaccinated?
A: Getting COVID-19 after being fully vaccinated, which is considered once two weeks have passed since completing the vaccine series, is referred to as a breakthrough infection.
Last week, the U.S. Centers for Disease Control and Prevention reported about 5,800 breakthrough cases among more than 75 million Americans who have been fully vaccinated. Although that seems like a big number, the reported risk is only 0.008%. The important point to make is that these breakthroughs are actually expected, since the vaccine’s protection is not 100%. When millions of vaccines are administered, even things that occur relatively infrequently will occur.
There could be other reasons for breakthrough infections. If you get infected before being fully vaccinated, for example, your body may not have had enough time to mount an appropriate response. Older people and those with compromised immune systems may not mount an appropriate response because of underlying medical conditions. Some variants might cause illness in some people after being fully vaccinated, and others could have had exposure to higher viral loads. The CDC reported that vaccination will likely make breakthrough infections less severe.
The reported breakthrough cases were seen in all ages, but mostly in adults older than 60 years of age (45%) and mostly in females (65%). A small percentage were hospitalized, but many of the positive cases did not have symptoms. Of the hospitalized cases, 1% died, but not all were a result of having the infection. The CDC is continuing to monitor breakthrough cases to identify specific characteristics of those affected, which vaccine was administered, length between full vaccine status and infection, and to identify variants.
Breakthrough cases highlight why it is still important to practice physical distancing and wearing a mask – even after you have been fully vaccinated. The number of breakthroughs will depend on how much virus is circulating in the community – and the best way to decrease transmission is to assure that everyone gets vaccinated.
Fernando Urrego, M.D., is the interim health officer at the Hamilton County Health Department and a member of the Chattanooga-Hamilton County Medical Society.
Contributed Photo / Dr. Fernando Urrego