Studys Show Moderna is More Effective Than Pfizer Against Delta Variant

But, both vaccines help reduce COVID-19 hospitalizations and deaths.

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Scientific studies show that Moderna may be more effective against the COVID 19 delta variant than the Pfizer/BioNTech mRNA vaccine. MedRxiv posted two reports on Sunday highlighting the studies’ findings.

The studies showed that the odds of a breakthrough COVID-19 diagnosis rise with time. Anyone who received a second dose of the Pfizer/BioNTech vaccination shots more than five months ago is more likely to have a positive test result for COVID-19’s delta variant. Conversely, people who were fully vaccinated less than five months ago are likely to have a more substantial degree of protection.

According to the two reports, which were posted ahead of a peer review, a study of 50,000-plus Mayo Clinic patients showed that Moderna’s vaccine effectiveness against infection of the novel coronavirus fell to 76 percent by July. That was the month that the delta variant became the dominant COVID strain in the U.S. Earlier in 2021, the Moderna vaccine showed an 86 percent effectiveness against the virus.

During the same period, Pfizer’s vaccine had a 76 percent effectiveness at its peak but fell to 42 percent in July. However, both vaccines are noted to remain highly productive at preventing hospitalization when infected with the COVID virus. 

The leader of the study, Dr. Venky Soundararajan, said that a Moderna booster vaccine would likely be recommended for people who received either the Moderna or the Pfizer vaccine early this year.

In a separate Ontario study, elderly residents living in a nursing home had a more robust immune response against more dangerous COVID-19 variants when given the Moderna vaccine over other types of vaccines.

Anne-Claude Gingras of Toronto’s Lunenfeld-Tanenbaum Research Institute said older people would likely need to undergo boosters, higher vaccine doses, and other measures to prevent infection. Gingras led the study in Toronto.

“We continue to believe…a third dose booster may be needed within 6 to 12 months after full vaccination to maintain the highest levels of protection,” a Pfizer spokesperson acknowledged.

New data suggests that those who had their second dose of the Pfizer vaccine more than five months ago are more likely to become infected with COVID-19 than those vaccinated less than five months ago.

In Israel, research shows that among 34,000 fully-vaccinated adults, 1.8 percent had a breakthrough COVID diagnosis. Across all age groups, subjects were more likely to test positive when they received their last vaccine 146 or more days ago. In patients over 60, their chances of receiving a positive test result for COVID were nearly three times higher once the 146 days had passed.

According to Dr. Eugene Merzon of Leumit Health Services in Israel, the majority of the new infections occurred recently.

But, Dr. Merzon noted: “Very few patients had required hospitalization, and it is too early to assess the severity of these new infections in terms of hospital admission, need for mechanical ventilation, or mortality. We are planning to continue our research.”



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