Last October, the Centers for Disease Control and Prevention (CDC) advised a second updated COVID-19 vaccine dose for high-risk adults to bolster their protection against the ever-evolving virus.
Now, the agency is recommending that individuals aged 65 and older, as well as those with weakened immune systems, receive a second dose of the 2024-25 vaccine six months after their initial dose.
This isn’t the first time the CDC has recommended an additional dose for vulnerable populations several months after their first. In the spring of 2022, a second booster shot was authorized. A similar pattern repeated in the springs of 2023 and 2024.
While other vaccines aren’t administered with such frequency, experts affirm that there’s no reason to doubt the effectiveness of these vaccines, particularly the mRNA vaccines developed by Pfizer and Moderna.
Pfizer and Moderna’s vaccines were pioneers, using mRNA technology to induce immunity against a virus. This approach proved crucial in the pandemic’s early days because mRNA vaccines can be developed much faster than traditional vaccines.
Despite the CDC’s recommendation, there’s no evidence suggesting that mRNA vaccines aren’t functioning as intended, according to Dr. Akiko Iwasaki, a noted immunologist at Yale School of Medicine.
Dr. Iwasaki suggests that the reason behind the need for additional doses might lie in the unique characteristics of the virus, which seem to prevent the body from maintaining high immunity levels.
Recent research from Emory University revealed that “hybrid immunity” – the result of being both vaccinated and infected with the coronavirus – wasn’t significantly building certain long-lasting cells that produce antibodies. This wasn’t the case for vaccines against influenza and tetanus, hinting that something distinct is happening with COVID-19, according to Dr. Iwasaki.
“You would assume that kind of hybrid immunity would be the most robust, and yet they didn’t observe increases in these long-lived plasma cell numbers,” she stated.
Dr. Ashish Jha, Dean of the Brown University School of Public Health and former White House COVID-19 Response Coordinator, acknowledges some uncertainty surrounding the longevity of mRNA vaccine protection compared to older vaccine technologies.
“It might be slightly less durable,” Dr. Jha noted, adding “Although, I wouldn’t say we know for sure.”
The bigger concern, Dr. Jha emphasizes, lies in how rapidly the virus mutates and its year-round presence.
“The problem here isn’t so much with the vaccine, but much more with the virus itself,” he explained, adding that he supports the updated guidance.”It’s what I’ve actually been recommending to my own parents, and what I’ve stated publicly.”
These guidelines come amidst growing concerns about waning vaccine immunity, particularly in older adults, who may be more susceptible to severe illness and hospitalization.
“It’s a good idea to top up your vaccine-induced immunity every six to 12 months,” suggested Dr. E. John Wherry, an immunologist at the University of Pennsylvania.
The vaccine boosts antibody levels, which act as the first line of defense against the virus, he explained. “This makes it easier for your remaining immune system to eliminate the virus and prevent serious illness.”
The Ever-Changing Virus
“We carefully analyze flu vaccine strains each year, striving for the best possible match,” explained Dr. Anna Durbin, an infectious disease physician and associate professor at the Johns Hopkins University School of Medicine. “COVID-19 is even more dynamic – continuously mutating to gain an advantage.”
One reason we don’t frequently need boosters for diseases like measles is because it doesn’t mutate as quickly as the coronavirus.
“A measles virus encountered today is very similar to one encountered five or ten years ago,” Dr. Jha stated.
Ideally, COVID-19 vaccines would be updated much faster to align with circulating strains.
“By the time we determine which COVID strain to target for the new vaccine, and by the time it’s ready for distribution, the virus has already mutated,” Durbin explained.
“The question is whether we can boost immunity, even if it’s not a perfect match to the current strain,” she said. Hopefully, this boosted immunity will provide better protection for those most at risk.
Dr. Jha doesn’t foresee twice-yearly vaccinations becoming a universal recommendation for all age groups, as a 30-year-old’s immune system is significantly stronger than an 80-year-old’s.
“Unless the virus becomes more severe,” he stated, “which I don’t anticipate happening.”
Interview Between Time.news Editor and Dr. Akiko Iwasaki on COVID-19 Vaccine Trends
Time.news Editor (TNE): Good morning, Dr. Iwasaki. Thank you for joining us today to discuss the recent recommendations from the CDC regarding COVID-19 vaccinations for high-risk populations.
Dr. Akiko Iwasaki (AI): Good morning! It’s my pleasure to be here.
TNE: The CDC has advised that individuals aged 65 and older, along with those with weakened immune systems, receive a second dose of the 2024-25 COVID-19 vaccine six months after their initial dose. This pattern of recommending additional boosters isn’t new, correct?
AI: That’s correct. We’ve seen a similar trend in the spring of 2022, 2023, and now into 2024. The ongoing need for additional doses stems from a combination of factors, including waning immunity and the virus’s ability to mutate rapidly.
TNE: It can be concerning to many that we need to boost our immunity so frequently compared to traditional vaccines. Do you think this reflects on the effectiveness of the mRNA vaccines created by Pfizer and Moderna?
AI: Not at all. In fact, the mRNA vaccines have proven to be effective and resilient, especially given how quickly they were developed and deployed during the pandemic. However, the unique characteristics of the COVID-19 virus appear to prevent the body from maintaining high levels of immunity over time.
TNE: That’s intriguing. You mentioned hybrid immunity from simultaneous vaccination and infection doesn’t significantly increase long-lived antibody-producing cells. Can you elaborate on that?
AI: Certainly. Research from Emory University indicated that hybrid immunity is not producing the expected increase in long-lived plasma cells. This is notable compared to other diseases, such as influenza or tetanus, where hybrid immunity does typically enhance those protective cells. This tells us there’s something distinct happening with the immune response to COVID-19.
TNE: Dr. Ashish Jha emphasized that the concern lies more with the virus than the vaccine itself. What are your thoughts on this dual perspective regarding vaccination and the virus’s evolution?
AI: I completely agree. The virus’s variable mutations and its year-round presence complicate our immune response. While the vaccines have proven effective, the constant evolution of the virus creates challenges for maintaining long-term, robust immunity. It often means we need to adapt our response, including getting boosters, to keep up with those changes.
TNE: The CDC’s advice aligns with a proactive approach to immunity, especially for older adults. Dr. E. John Wherry has suggested getting vaccine boosts every six to 12 months. How do you see this impacting public health?
AI: Regular booster shots can significantly enhance protection, especially for vulnerable populations. It’s a strategic approach to manage ongoing risks, particularly for older adults who are more susceptible to severe illness. Ensuring an adequate level of immunity is crucial, and improved antibody levels can act as the first line of defense against the virus.
TNE: With all this information, what message would you give to our readers, especially those who may still be hesitant about vaccinations?
AI: I would urge them to stay informed. The science supporting mRNA vaccines is robust, and even as we face challenges with COVID-19, these vaccines remain a key tool for enhancing our immunity. Engaging with healthcare providers and understanding that updates and guidelines are based on the latest research can help everyone make informed decisions for their health and the health of their communities.
TNE: Thank you, Dr. Iwasaki, for shedding light on these important developments surrounding COVID-19 vaccinations. We appreciate your insights.
AI: Thank you! It’s been a pleasure discussing these crucial topics.