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CDC: Two-dose mRNA vaccines best at avoiding hospitalisations

In terms of preventing COVID-related hospitalisations, the two-dose mRNA vaccines from Pfizer (Comirnaty) and Moderna offered the best protection upfront and over time, a case-control analysis involving data from 21 US hospitals showed.

Medpage Today writes that from March to August 2021, the vaccine effectiveness (VE) against COVID-19 hospitalisations landed at 93% for the Moderna vaccine, 88% for Pfizer's, and 71% for Johnson & Johnson's (J&J), reported Dr Wesley Self, of Vanderbilt University Medical Center in Nashville, Tennessee, and colleagues, in the Morbidity and Mortality Weekly Report.

After 120 days from the time of vaccination, however, Moderna's VE against hospitalisation only dipped to 92%, a non-significant decline, while Pfizer's dropped to 77%.

"Differences in VE between the Moderna and Pfizer-BioNTech vaccine might be due to higher mRNA content in the Moderna vaccine, differences in timing between doses (three weeks for Pfizer-BioNTech versus four weeks for Moderna), or possible differences between groups that received each vaccine that were not accounted for in the analysis," Self and co-authors suggested.

No data were shown for the J&J shot after 120 days due to the limited number of patients who received the vaccine, but the VE rate dipped to 68% for the single-dose vaccine after 28 days.

A second analysis in the study, involving 100 patients, showed that individuals vaccinated with the one-dose J&J viral vector vaccine had lower anti-SARS-CoV-2 antibody levels at two to six weeks after being fully vaccinated compared with the mRNA vaccine recipients. Antibody levels were slightly higher with Moderna's versus Pfizer's.

“Although an immunologic correlate of protection has not been established for COVID-19 vaccines, antibody titers after infection and vaccination have been associated with protection,” the group wrote.

The findings came from a sample of 3,689 adults without immunocompromising conditions (1,682 case patients and 2,007 controls) admitted with COVID-19 to one of 21 US hospitals across 18 states from 11 March to 15 August. Median patient age was 58 years and slightly fewer than half were women, while 53% were white, 23% were black, and 18% were Hispanic.

Overall, 20% were fully vaccinated with Pfizer's vaccine, 12.7% with Moderna's, and 3.1% with the J&J vaccine; 64.0% were unvaccinated.

Limitations of the study included that it was limited to non-immunocompromised adults, the limited number of J&J recipients, and that follow-up time after being fully vaccinated was only about 29 weeks. Notably, data on VE were not evaluated by SARS-CoV-2 variant, including the Delta variant.


MedPage Today article – One COVID Vaccine Held Up Best Over Time, CDC Study Suggests (Open access)


CDC MMWR – Comparative Effectiveness of Moderna, Pfizer-BioNTech, and Janssen (Johnson & Johnson) Vaccines in Preventing COVID-19 Hospitalizations Among Adults Without Immunocompromising Conditions — United States, March–August 2021 (Open access)


See more from MedicalBrief archives:


Pfizer and Moderna cut COVID-19 infection risk by 91% in the fully vaccinated


Moderna modifying COVID-19 vaccine to protect against emerging strains


CDC panel backs third Pfizer and Moderna shot for the immunocompromised


Vaccine potency dips 11 percentage points over 8 months — HEROES-RECOVER



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