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“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.