Opinion | Are Americans Aware of the Extended COVID Vax Dosing Interval?

We applaud the CDC’s decision last week to update its guidelines to incorporate an extended dosing interval (with 8 weeks between initial mRNA vaccine doses) for younger individuals (12-39 years old) who are not moderately or severely immunocompromised. This decision follows the favorable discussion by the agency’s Advisory Committee on Immunization Practices. As we outlined in our recent MedPage Today opinion piece, the evidence strongly supports extended intervals between vaccine doses on the basis of 1) immunological research 2) vaccine effectiveness and 3) safety.

The extended interval dosing signals the CDC is leading with evidence-based guidelines. However, the change still requires more clear messaging and more robust efforts by the CDC to publicize this recommendation to reach as many people as possible.

Make 8 Weeks the Default Interval

The interim update was made on February 22 as a footnote to one of the tables on the CDC’s webpage that is geared toward healthcare professionals: “Interim Clinical Considerations for Use of COVID-19 Vaccines Currently Approved or Authorized in the United States.” However, we have a few suggestions. In Table 2 on the professionals-focused webpage, CDC should remove the “3-8 weeks” for the Pfizer vaccine interval and the “4-8 weeks” for the Moderna vaccine interval and make “8 weeks” as the default. The footnote under the table indicates who should receive the vaccines using a shorter dosing interval (e.g. people who are moderately to severely immunocompromised; adults ages 65 years and older; and others who need rapid protection due to increased concern about community transmission or risk of severe disease).

We also recommend the CDC consider extending the dosing interval for the 5-11 age group (currently 3 weeks between Pfizer doses) after performing research to evaluate the safety and effectiveness of this approach. The National Advisory Committee on Immunization in Canada currently recommends a longer (8-week) dosing interval for this group based on principles of immunology.

By making these changes, the CDC would be accentuating that an 8-week interval of the primary series should be the default and will clarify that the shorter dosing interval is more appropriate only for select groups.

Publicize the Longer Dosing Interval

The CDC should also more publicly promote the modified recommendation by updating the guidelines on its webpage for the general public (“Vaccines for COVID-19“) and in press releases to the media, both of which have been noticeably absent.

Greater transparency of these updated evidence-based guidelines can encourage vaccination among those who remain vaccine hesitant or parents who have not yet vaccinated their children due to concerns of myocarditis. With the extended 8-week dosing interval showing evidence of a lower risk of myocarditis, emphasizing this message may be the push parents need to vaccinate their kids.

The extended dosing interval recommendation has become even more urgent with newly emerging evidence around the vaccine for kids. A large analysis from New York showed that vaccine effectiveness against infection among children 5 to 11 years old declined considerably in the Omicron era. While protection against hospitalization declined too, it still remained fairly high (48% in kids 5-11 and 73% in kids 12-17). Of note, this analysis of administrative data could not determine prior infection status among the unvaccinated so the calculated vaccine effectiveness may appear lower since those with previous infection will have some immunity. CDC data released on Tuesday from 10 states, including New York, had somewhat different findings for the 5-11 group, with two doses of Pfizer vaccine showing 51% protection against emergency department and urgent care visits during Omicron, and 74% effectiveness against hospitalization across the Delta and Omicron waves. While more research is needed, both studies point to decreasing protection against Omicron for younger age groups. Increasing the duration between doses for younger children can increase immunogenicity, as evidenced by this Cell paper showing increased antibody and T cell responses with longer intervals of the Pfizer vaccine and this JAMA paper showing similar findings. While these studies look at the response in adults, studies have verified that longer intervals between vaccine doses for other infections in children increase immunogenicity, forming the basis for the childhood vaccination schedule.

In light of this emerging data, what’s the best next step? Vaccine safety remains high with the 8-week dosing interval, and while vaccine protection against infection appears to have declined among kids, the COVID-19 vaccine still offers important protection against severe illness and hospitalization. With a more strongly worded and publicized recommendation from the CDC, doctors can discuss this with their patients and help convince them to get vaccinated.

Michael Daignault, MD, is an emergency physician at Providence Saint Joseph Medical Center in Burbank, California. Monica Gandhi, MD, MPH, is a professor of medicine in the school of medicine at University of California San Francisco.