The Centers for Disease Control and Prevention announced this new recommendations for COVID-19 vaccination doses. It was no surprise to many in healthcare that a second dose was recommended for people aged 65 and over or for young people with moderate or severe immunocompromise.
What was somewhat unexpected, although positive, is that it now recommends “flexibility for additional doses (i.e. three or more) for those who are moderately or severely immunocompromised, in consultation with their healthcare provider (a strategy known as shared clinical decision making).”
The Advisory Committee on Immunization Practices had discussed such an approach last summer. Some argue that a standard, universal approach is easier for patients and healthcare providers to understand. Others advocated moving toward one risk-based strategy. The CDC still recommends one dose of the 2024-2025 COVID-19 vaccine for people ages 5 to 64 who are not immunodeficient.
There had been quite a bit of public pressure for the changes and for the recommendation that everyone be vaccinated every six months instead of annually. Many pushed for immunocompromised people to get a second COVID-19 vaccine two months after the first.
Over the past four and a half years, we have seen that COVID-19 is not as seasonal as the flu; waves of infection have occurred throughout the year. Therefore, for many it made no sense to only propose an annual autumn vaccination in combination with the flu vaccine.
One of the problems is that the vaccines are poorly absorbed, even when they are available. Only 22.5% of adults and 14.1% of children received the vaccine between 2023 and 2024. Less than 9% of adults 65 and older received two or more doses of the 2023-2024 COVID-19 vaccine.
Uptake has undoubtedly declined since then as the CDC’s Bridge Access Program, which provides free COVID-19 vaccines to under- or insured patients, ended in August. Since then, the cost of the vaccine for uninsured people has not been paid by the government, but passed on to individuals, and many can hardly afford it.
There is also ample data showing the vaccine’s effectiveness against hospitalization decreases significantly by four to six months in people aged 65 and over. In the period 2023-2024: the effectiveness of vaccines against hospitalization in immunocompromised people decreased even furtherto 0 by approximately four to six months (p. 17).
One question is what criteria Medicare/Medicaid or private insurers must meet to cover additional doses for immunocompromised patients. Can patients pay out of pocket if they want an extra dose but don’t meet the criteria? If someone is protecting an at-risk family member, can they get covered for three or four doses per year?
Another interesting recommendation from ACIP is to use vaccines from the same manufacturer (homologous vaccines). This was surprising because in some previous studies a mix-and-match (heterologous) approach seemed advantageous. The FDA, for example, took notice heterologous boosters resulted in similar or higher serological responses than homologous boosters.
Why does the CDC recommend sticking with the same manufacturer now?
Dr. Eric Topol, founder of the Scripps Research Translational Institute, said this may be because there is wide variability in the responses (neutralizing Abs and T cells) to the mix-and-match strategy, but there are no studies demonstrating clear differences in clinical outcomes. . Another expert hypothesized that this is because the vaccines from different manufacturers target different virus strains. Novavax is strongest against the JN.1 line, but the mRNA vaccines target the FLiRT variants.
The CDC did not respond to specific, detailed questions about these issues. It is welcome news that immunocompromised patients can be better protected by flexibility in allowing more frequent immunizations. But the devil is in the details of how this can – or will – work in practice. It looks like we’ll have to wait for further clarification.*
*CDC responded on 10/25 at 6:00 PM that “If ACIP approves schedule changes, insurers will cover the cost of vaccines.”