Latest CDC study: Both 2-dose COVID vaccines provide more protection than 1-dose J&J shot


A woman holds up a sticker after getting her third “booster” dose of Covid-19 vaccine at a clinic hosted by The Tournament of Roses in partnership with the Pasadena Public Health Department, August 19, 2021 at Tournament House in Pasadena, California. – The clinic is one of the first in the city to offer “supplemental” third Covid-19 shots to people with immunological conditions, according to organizers.
President Joe Biden said August 18 he will make Covid-19 booster shots available to all American adults beginning next month, as his administration warned that vaccines are showing a declining effectiveness against infection. (Photo by Robyn Beck / AFP) (Photo by ROBYN BECK/AFP via Getty Images)

TAMPA, Fla. (WFLA) — The latest study on vaccine effectiveness by the U.S. Centers for Disease Control and Prevention shows that the two-dose vaccines from Pfizer and Moderna provide more protection that the Johnson & Johnson shot, and may last longer over time.

Of the two-dose vaccines, the most recent Morbidity and Mortality Weekly Report, published Sept. 17, found that Moderna’s shot retains a higher efficacy rate over time than the one from Pfizer-BioNTech, though both are more protective than the J&J single-dose vaccine.

Comparing the three vaccines, focus has to first look at how they differ. Both Moderna’s and Pfizer’s two-dose vaccines are mRNA vaccines, while the Johnson & Johnson vaccine is a single-dose viral vector vaccine.

According to the CDC, a viral vector vaccine works by using “a modified version of a different virus (the vector) to deliver important instructions to our cells.” The benefit here, according to the CDC, is that the vaccine teaches our bodies how to protect themselves against future infections of viruses it’s made to block.

By comparison, “mRNA vaccines teach our cells how to make a protein—or even just a piece of a protein—that triggers an immune response inside our bodies.” The mRNA vaccine teaches our bodies to understand that the protein it builds in our cells doesn’t belong, then defends against it with the immune response.

The CDC says none of the COVID-19 vaccines available affect or interacts with our DNA in any way. All three currently approved vaccines have been declared safe and effective.

The latest MMWR study on COVID vaccines took a look at the long-term effectiveness of the three vaccines available, and studied how well they protected patients over time.

According to the study, vaccine effectiveness, or VE, was higher for Moderna than for the Pfizer vaccine, and both were more effective than the Johnson & Johnson vaccine.

The patients studied were hospitalized from March 11 to Aug. 15, 2021.

The study results showed that Moderna’s efficacy for hospitalized patients was 93% compared to Pfizer’s 88%. The J&J vaccine was 71% effective. After administering second doses, the Pfizer vaccine efficacy dropped to 77% after the 120-day mark, while Moderna remained higher at 92%.

From the study:

“VE against COVID-19 hospitalization during March 11–August 15, 2021, was higher for the Moderna vaccine (VE = 93%) than for the Pfizer-BioNTech vaccine (VE = 88%) (p = 0.011); VE for both mRNA vaccines was higher than that for the Janssen vaccine (VE = 71%) (all p<0.001) (Table 2). VE for the Moderna vaccine was 93% at 14–120 days (median = 66 days) after receipt of the second vaccine dose and 92% at >120 days (median = 141 days) (p = 1.000). VE for the Pfizer-BioNTech vaccine was 91% at 14–120 days (median = 69 days) after receipt of the second vaccine dose but declined significantly to 77% at >120 days (median = 143 days) (p<0.001).”

MMWR Vol. 70, published on Sept. 17, 2021 by the CDC

The study’s Discussion section dives deeper into the results of the data.

“Two-dose regimens of the Moderna and Pfizer-BioNTech mRNA vaccines provided a high level of protection against COVID-19 hospitalizations in a real-world evaluation at 21 U.S. hospitals during March–August 2021,” according to the CDC study.

Additionally, the study found that patients who received the Johnson & Johnson vaccine had lower levels of post-vaccination anti-SARS-CoV-2 antibodies than patients who received either of the mRNA two-dose vaccines.

The “real-world” data from the CDC suggested that the two-dose vaccine regimens give patients more protection and higher vaccine effectiveness, but all three still reduce COVID-19-associated hospitalization.

“Two-dose series of the Moderna and Pfizer-BioNTech mRNA COVID-19 vaccines provided high VE for the prevention of COVID-19 hospitalizations during March-August 2021,” the MMWR says.

Still, all three vaccines are FDA approved, though only the Pfizer vaccine has received full authorization for patients 12-years-of-age or older. The Moderna mRNA vaccine and the J&J viral vector vaccine are both approved with an emergency use authorization for patients 12 and older, and trials are underway to test for the effectiveness of booster shots.

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