COVID-19 risks for the vaccinated

Each day, there seems to be a lot of news — both bad and good — related to the COVID-19 pandemic. Lately, the bad news is that the more contagious delta and omicron variants are causing a surge of new cases and hospitalizations, especially among people who have not yet received a COVID-19 vaccine. The good news is that more people are getting vaccinated on a daily basis — though not nearly enough to help slow community spread and end the pandemic.

While those who are fully vaccinated — at least 2 weeks have passed since receiving their second dose of either the Pfizer or Moderna vaccine, or single dose of the Johnson & Johnson vaccine — and have received a booster dose are largely avoiding infection, there is a small risk of "breakthrough infections." And not all vaccinated people will have the same experience if they are exposed to the coronavirus.

"Everyone reacts differently when exposed to a virus," says Dr. Jyotu Sandhu, a family medicine doctor with Sharp Rees-Stealy Medical Group. "Some people will experience infection, some won't. Some will experience symptoms that others don't, or will experience them at a lesser or greater severity than others. The important thing to remember is that vaccination is highly effective at protecting you against serious illness, hospitalization and death, and any breakthrough cases will likely result in no symptoms or very mild symptoms."

What do the numbers tell us?
While case numbers are increasing — predominantly among the unvaccinated, but also among a small number of people who have been fully vaccinated — recent reports show that the rate of cases in vaccinated individuals remains low.

Additionally, in the U.S., 97% of people hospitalized with COVID-19 are unvaccinated. Of the small percentage of hospitalized people who have been vaccinated, many of them have other risk factors, such as advanced age, chronic illness or a compromised immune system.

Are the vaccines still working?
With this increase in breakthrough infections, many have wondered if the protection initially provided by the vaccines has decreased over time. While vaccines remain extremely effective at preventing severe illness and death, Dr. Sandhu suggests they may not be as effective at preventing infection or transmission as they were before the emergence of the delta and omicron variants.

However, experts agree the effectiveness of the vaccines is still considered impressive against the delta and — when a booster dose is received — the omicron variants. 

It is more likely that the unique characteristics of the delta and omicron variants are causing the increase in cases, both in the unvaccinated and vaccinated. Unlike the original coronavirus that causes COVID-19, studies show the delta and omicron variants may:

• Be more contagious for both adults and children

• Be associated with a higher viral load of infection and a longer phase of transmissibility (can be spread more widely and rapidly)

• Lead to infections in vaccinated people that spread as easily as infections among unvaccinated people

These differences have led the Centers for Disease Control and Prevention (CDC) to acknowledge that "the war has changed." The focus, they say, must now be on vaccinating as many people as possible, but also on encouraging people to identify their own personal risk — and the risk of loved ones — for severe illness, and taking steps to decrease that risk.

The agency determined that everyone — vaccinated or not — should consider the following and act accordingly:

• The transmission rate of COVID-19 in their community

• The vaccination rate of the people surrounding them, recognizing that children under age 5 are not yet eligible to receive a COVID-19 vaccine

• Their own immunocompromising conditions, such as age and chronic illness

• The immunocompromising conditions of their loved ones

What safety guidelines have changed due to the delta variant?
With these considerations in mind, the CDC now recommends that fully vaccinated people wear a mask in public indoor spaces. A return to universal masking indoors is particularly crucial if people are at increased risk for severe illness from COVID-19 or if they have someone in their household who is at increased risk of severe illness or is not fully vaccinated. This includes children under age 5, who are not yet eligible to receive a COVID-19 vaccine.

Additionally, vaccinated people should:

• Get tested if experiencing symptoms of COVID-19 — including headache, sore throat, runny nose and fever

• Be tested 5 to 7 days after a known exposure to someone with suspected or confirmed COVID-19 and wear a mask in public indoor settings and around others for 14 days or until they receive a negative test result

Dr. Sandhu also recommends that people wear a face mask when in crowded outdoor spaces, or avoid large crowds altogether, until more people are vaccinated and the spread of COVID-19 slows. "When you take a gathering that's outdoors, but cram people together in close proximity, the outdoor ventilation really loses its value," he says.

Do fully vaccinated people need a booster?
The Food and Drug Administration (FDA) recently amended the emergency use authorization (EUA) for the Pfizer COVID-19 vaccine to allow fully vaccinated people age 16 and older to receive a third booster dose. The Moderna EUA was also amended to allow those age 18 and older to receive a booster dose once eligible. Both Pfizer and Moderna say a third shot will provide an increased immune response to the coronavirus.

"There is no denying that community spread, along with increased hospitalizations and deaths, is occurring primarily among people who are unvaccinated, so our first priority is to get these individuals their first and second doses while we wait for guidance on the need for a booster for those already vaccinated," Dr. Sandhu says.

"Vaccinating as many people as possible within communities will not only save lives, but also slow the spread of COVID-19, prevent the development of further variants, and allow us to more quickly return to normalcy. If you haven't already, please get vaccinated."

Sharp HealthCare joins the Centers for Disease Control and Prevention (CDC) in encouraging everyone who is eligible to receive a COVID-19 vaccine. Get COVID-19 vaccine information and access to COVID-19 resources from Sharp.

This article was updated in December 2021.