Moderna vaccine recipients have lower risk of breakthrough infections, hospitalization: study

A new study has found that people who received the Moderna COVID-19 mRNA vaccine are less likely to experience breakthrough infections compared to those who received the Pfizer-BioNTech mRNA shot.

The study, led by researchers out of Cleveland's Case Western Reserve University, also found that people who received the Moderna jab were less likely to be hospitalized following a breakthrough infection than Pfizer vaccine recipients.

The findings were published Thursday, in the peer-reviewed Journal of the American Medical Association.

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A breakthrough infection is when an individual tests positive for COVID-19 more than 14 days after completing the recommended series of a two-dose COVID-19 vaccine.

According to the study, researchers examined the electronic health records of more than 637,000 fully vaccinated patients from 63 healthcare organizations across the U.S., analyzing breakthrough COVID-19 infections, hospitalizations, and death rates between July and November 2021, when the Delta variant was the dominant virus strain circulating in communities.

According to the study, incidents of breakthrough infections were included if the person had not been previously infected with COVID-19 or had received a booster shot.

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Researchers say the records included fully vaccinated patients from diverse geographic backgrounds, ages, races and ethnicities, income levels, and insurance groups.

"Breakthrough COVID infections, hospitalization and mortality associated with the Delta variant were compared between recipients of Moderna mRNA vaccine and recipient of Pfizer mRNA vaccine while considering patient characteristics and the varying time since vaccination," said Rong Xu, study author and Case Western bioinformatics professor, in a press release.

The study found that the "monthly incidence rate" of breakthrough cases was higher among those who received the Pfizer vaccine, compared to Moderna.

For example, researchers reported that the data showed 2.8 breakthrough cases per 1,000 Americans in those vaccinated with Pfizer, compared to 1.6 cases in Moderna recipients for November 2021.

When it came to hospitalizations, the study found that the 60-day rate for Moderna recipients was 12.7 per cent, compared to 13.3 per cent for those who received the Pfizer vaccine.

However, the study says there was "no significant difference" in mortality rates among recipients of the two vaccines.

The findings come after some pharmacies in Ontario reported earlier in January that people are walking out after being informed that they would be receiving the Moderna vaccine rather than Pfizer's for their booster shot.

The study's authors maintain that both vaccines are effective despite the difference in breakthrough rates. They say more research is needed in the future to assess these rates following booster doses.

"Although there is a difference in breakthrough infections, both vaccines are highly protective against SARS-COV2 infection and especially against the most severe consequences of infection," said study co-author Pamela Davis in the release.