- The CDC has found reduced vaccine effectiveness in people who are immunocompromised compared with people who are not. It now advises that certain people who are immunocompromised can get a fourth vaccine dose.
- One reason for these new guidelines is that vaccine efficacy has been shown to drop over time, placing certain groups at increased risk.
- About 3 percent of U.S. adults, or about 7 million people, are immunocompromised.
In updated guidelines released this week, the Centers for Disease Control and Prevention (CDC) said certain people who received the Moderna or Pfizer COVID-19 vaccine will be eligible for a fourth dose.
"Moderately and severely immunocompromised people aged ≥18 years who completed an mRNA COVID-19 vaccine primary series and received an additional mRNA vaccine dose may receive a single COVID-19 booster dose (Pfizer-BioNTech, Moderna, or Janssen) at least 6 months after completing their third mRNA vaccine dose," the CDC wrote.
The CDC has found reduced vaccine effectiveness in people who are immunocompromised compared with people who are not immunocompromised.
According to the American Medical Association (AMA), slightly less than 3 percent of U.S. adults, or about 7 million people, are immunocompromised.
This past August, the CDC estimated only a fraction of those 7 million adults would need an additional dose. Although, CDC data currently shows almost 14 million people have received a booster or additional COVID-19 shot.
"We use the term 'additional' dose to refer to a subsequent vaccine dose in people who likely did not mount a protective immune response after their primary vaccination," the CDC's Dr. Sujan Reddy said in a recent webinar with healthcare professionals.
Also in August, the Food and Drug Administration (FDA) authorized the third additional vaccine dose for people who are immunocompromised.
According to the CDC, people with conditions that suppress the immune system, or those taking immunosuppressive medications or therapies are at increased risk of severe COVID-19.
"This includes patients being treated for active cancer, solid organ transplant recipients, advanced HIV infection, those on chronic immunosuppression, and a few other categories that are outlined by CDC," Dr. David Hirschwerk, an attending infectious diseases specialist at Northwell Health in Manhasset, New York, told Healthline.
While the FDA has specified that the third dose can only be the Moderna or Pfizer COVID-19 vaccine, according to the new guidelines, millions of U.S. adults with compromised immune systems can now get a fourth booster dose that includes the Johnson & Johnson vaccine as early as 6 months after receiving a third additional dose.
"Another important aspect of the recommendations [is that] any of the authorized COVID-19 vaccine booster doses, so that's Pfizer BioNTech, Moderna, or Janssen, can be used following any of the primary series vaccinations," Reddy said in a statement.
One reason for these new guidelines is that vaccine efficacy has been shown to drop over time, placing certain groups at increased risk.
A recent study found the Pfizer vaccine's efficacy waned significantly over time, going from 88 percent protection in the first month to only 47 percent after 5 to 6 months.
The vaccine's effectiveness against the Delta variant also declined from 93 percent in the first month to only 67 percent after 4 to 5 months.
"Over time, generally 6 to 9 months, the vaccine effectiveness appears to diminish," said Hirschwerk. "They do remain protective against developing severe infection, but less effective at preventing any infection at all."
Asked if waning immunity means at some point we're not protected by the vaccine at all, Hirschwerk confirmed that this isn't a concern.
"It means that the effectiveness diminishes," he explained. "[It] does not mean that it necessarily disappears entirely."
Hirschwerk pointed out that the continual changes to CDC recommendations are a sign that the agency is doing its job as intended.
"The CDC is appropriately trying to adjust to the science learned and will continue to update their recommendations based on the COVID situation," He said. "That's what we want to see. We all need to keep a lookout for updated recommendations as they are issued and respond to them."
Asked if eventually we'll all need a booster shot to be considered fully vaccinated, Hirschwerk said no, not at this point, "But stay tuned."
New CDC guidelines mean some people will be eligible for a fourth vaccine dose. These include those who are taking certain medications, or who have a condition that suppresses the immune system.
Although previously authorized booster shots excluded the Johnson & Johnson vaccine, the new recommendation now includes it.
Experts say the changing advice from the CDC means that the agency is adjusting to the science and adapting recommendations to new information as it becomes available.
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