September 25, 2023

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Moderna COVID-19 Vaccine Shows Higher Safety for Seniors than Pfizer-BioNTech’s

Moderna COVID-19 Vaccine Shows Higher Safety for Seniors than Pfizer-BioNTech’s


Moderna COVID-19 Vaccine Shows Higher Safety for Seniors than Pfizer-BioNTech’s.


Researchers at Brown University have found that the Moderna vaccine carries a slightly lower risk of certain adverse events among elderly individuals compared to the Pfizer-BioNTech vaccine.

This study, involving over six million elderly individuals, underscores the significance of understanding real-world vaccine performance and suggests the need for continued research in the context of subsequent vaccinations and new vaccine developments.


Moderna COVID-19 Vaccine Shows Higher Safety for Seniors than Pfizer-BioNTech's


A study led by researchers from Brown University focusing on the elderly population in the United States has revealed that both mRNA vaccines exhibit very low risks of adverse effects, with Moderna’s vaccine showing the lowest risk.


While mRNA vaccines for COVID-19 have been demonstrated as safe and effective for the general population, robust evidence regarding their safety and efficacy in the elderly and those with chronic conditions has remained limited.


To address this gap, researchers led by Brown University conducted a comparative study of the two mRNA vaccines authorized by the U.S. Food and Drug Administration – Moderna and Pfizer-BioNTech. Published on August 2nd in JAMA Network Open, the study indicates that for elderly individuals, the risk of adverse events with the Moderna vaccine is slightly lower than that associated with the Pfizer-BioNTech vaccine.


Lead author of the study, Daniel Harris, an epidemiologist and research scientist at Brown University’s School of Public Health’s Center for Gerontology and Healthcare Research, stated, “The results of this study can help public health experts weigh which mRNA vaccine may be more appropriate for older adults and subgroups of older adults, such as those who are frail.”


Vaccines and the Elderly

The research encompassed over six million elderly individuals with an average age of 76 who received either the Moderna or Pfizer-BioNTech COVID-19 mRNA vaccines.

These two vaccines exhibit subtle differences in production, formulation, and immune response. The study affirms that the risk of severe adverse events is very low in both vaccine groups.


Comparative Analysis

Furthermore, the researchers observed a 4% reduction in the risk of pulmonary embolism (sudden blockage of lung blood vessels) following Moderna vaccination for these elderly individuals, and a 2% reduction in the risk of thrombotic events (defined as several conditions related to blood clotting).

In comparison to the Pfizer-BioNTech vaccine, the Moderna vaccine also demonstrated a 15% lower risk of diagnosing COVID-19.


Primary Considerations

Harris emphasized that the risk of adverse reactions following natural infection with the SARS-CoV-2 virus that causes COVID-19 is significantly higher than that associated with either mRNA vaccine.

However, with over 70% of the global population having received at least one COVID-19 vaccine, concerns over vaccine supply have diminished, making it essential to provide detailed information about vaccine effectiveness and safety to guide decisions.


Harris stated, “Getting either mRNA vaccine is far better and much safer than not getting vaccinated at all.

But in an ideal world, we can make choices about which vaccine product to use, and we want to see if there’s better performance in older adults and in people who are frailer.”


Harris believes that understanding vaccine performance in real-world populations remains necessary.

He pointed out that elderly individuals with chronic illnesses are often excluded from clinical trials or represent a minority.

Given that the elderly, especially those residing in nursing homes, face higher risks of severe COVID-19, this becomes particularly crucial. Immune responses to vaccines may also differ among frail elderly individuals, underscoring the importance of understanding vaccine efficacy in this vulnerable demographic.


Collaboration and Real-World Data

This research is part of a project called the IMPACT Collaboratory, led by Brown University researchers and Hebrew SeniorLife in Boston, in collaboration with CVS and Walgreens pharmacies.

The project involves large-scale monitoring of the long-term safety and efficacy of COVID-19 vaccination in Medicare beneficiaries.


Harris noted, “Because we have these real-world data and a cohort that includes millions of older adults, we’re able to tease out very small differences in vaccine safety and efficacy and analyze important clinical subgroups.”



Conclusions and Recommendations

According to the research team, the increased safety of the Moderna vaccine in events like pulmonary embolism could be linked to its stronger protection against COVID-19, particularly in non-frail elderly individuals.


“We think safety and efficacy are related,” Harris said. “We found that those who got Moderna were at slightly lower risk for pulmonary embolism and other adverse events, which may be because the Moderna vaccine is also more effective at reducing the risk of COVID-19.”


However, the study couldn’t definitively conclude whether the differences in adverse events are due to safety or efficacy, and researchers suggest further exploration in this realm.

The study also only analyzed the first dose of the mRNA vaccine, implying that similar comparisons could be made for subsequent doses in the future.


“As new vaccines come out, you can imagine that these types of analyses will be updated regularly,” Harris remarked. “Even within a small range, having one vaccine outperform another could have a significant impact on populations and drive a preference for that particular vaccine.”





Moderna COVID-19 Vaccine Shows Higher Safety for Seniors than Pfizer-BioNTech’s

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