麻豆传媒

Updated COVID shots are becoming available in the U.S. amid what appears to be a surge in cases -- leaving some to wonder whether they need an updated shot if they recently recovered from an infection.

states that people who are currently infected should wait "at least until recovery from acute illness" before getting a shot.

But they also "may consider delaying" their updated shot by 3 months from symptom onset, or from a positive test if the infection was asymptomatic.

Camille Kotton, MD, clinical director of transplant and immunocompromised host infectious diseases at Massachusetts General Hospital in Boston, who was a panelist on CDC's Advisory Committee on Immunization Practices (ACIP), emphasized that during the ACIP meeting on updated shots, it was noted that patients "can wait 3 months after an infection to get an updated vaccine."

"Wait about 3 months after recovery from infection to get the immunization," William Schaffner, MD, of Vanderbilt University Medical Center in Nashville, Tennessee, told 麻豆传媒. "That way the immune system will respond best to this shot. We know that the longer duration from the last stimulus, the somewhat better the response."

Some experts think the interval can go even a bit longer.

John Moore, PhD, a virologist at Weill Cornell Medicine in New York City, said there should be at least 4 months between infection and another shot.

Paul Sax, MD, clinical director of the division of infectious diseases at Brigham and Women's Hospital in Boston, said "even 6 [months] is reasonable" to wait before getting a new shot.

Moore said there's evidence "suggesting that a short interval can compromise the ability of the booster to trigger a strong antibody response" -- something the CDC acknowledges in its official recommendations.

"Studies have shown that increased time between infection and vaccination might result in an improved immune response to vaccination," the CDC guidance states. "Also, a low risk of reinfection has been observed in the weeks to months following infection."

While there are several studies supporting the notion of better results with a longer interval, Moore said a Cell stands out, showing that people who got a booster dose within 2 months of infection didn't have a robust neutralizing antibody or memory B-cell response compared with those who were boosted and didn't have a recent infection.

"B-cell responses to booster vaccines are impeded by recent infection," the paper concluded.

"There is no 'danger' involved, just reduced potency," Moore said.

Sax also noted that studies have shown that "people with hybrid immunity have sustained protection from hospital admission or severe disease."

Again, several studies have demonstrated this, Sax said, most notably a showing 97% effectiveness against hospital admission or severe disease at 12 months for hybrid immunity with primary series vaccination and infection.

Others remain unconvinced of the need for getting an updated shot after a recent infection at all. Paul Offit, MD, of Children's Hospital of Philadelphia, has long questioned the need for additional doses of the COVID vaccine beyond the primary series.

He had three doses of Pfizer and a natural infection in May 2022, and doesn't plan on getting the updated shot.

"This virus hasn't evolved away from T-cell recognition," Offit told 麻豆传媒. "T-cell recognition sites are well conserved. That's why we've gotten on top of this pandemic."

Someone who's young, healthy, and has recently been infected should have good protection against infection for 3 to 6 months, he said -- long enough to get through the winter.

Offit did say that someone recently infected who is over 75, or who has comorbid conditions or is immunocompromised, would be a different story, and additional protection against infection with an updated vaccine might be beneficial.

Moore similarly cautioned that especially for immunocompromised patients, "a physician who knows the patient's history well" would offer the best guidance for them.

Indeed, CDC guidance notes that "individual factors such as risk of severe disease or characteristics of the predominant strain should be taken into account when determining whether to delay getting a shot after infection."

While he's recommending the shot, especially to high-risk patients, Sax lamented the lack of data available for making the best recommendations around patient questions about updated COVID vaccines.

For people "who have had their primary vaccine series plus either a booster or COVID or both," Sax noted, "we lack prospective data from randomized trials that a strategy of further boosters (compared to none) will protect against severe disease."

"I do wish we had such data to make the recommendation more data-driven," he added.

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