• According to two reports published in medRxiv, the mRNA vaccine developed by Pfizer and BioNTech SE may be less effective than Moderna, Inc.'s against the Delta variant of the coronavirus, Reuters reports.
• The study, yet to be peer reviewed, included more than 50,000 patients in the Mayo Clinic Health System.
• Researchers found that efficacy of Moderna's Covid-19 vaccine dropped to 76% in July - when the Delta variant was predominant - from 86% in early 2021.
• However, during the same time, Pfizer/BioNTech vaccine's effectiveness decreased to 42% from 76%.
• While both vaccines remain effective at preventing Covid hospitalization, a Moderna booster shot may be necessary soon for people who got Pfizer or Moderna vaccines earlier this year, said Dr. Venky Soundararajan of Massachusetts data analytics company, who led the Mayo study.
• In a separate study, elderly nursing home residents in Ontario produced stronger immune responses - especially against variants - after the Moderna shot than after Pfizer/BioNTech vaccine.
• "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," said a Pfizer spokesperson.
• In a study posted on medRxiv, it was observed that breakthrough COVID-19 odds rise months after vaccination.
• The data suggested that people who received their second dose of the Pfizer/BioNTech vaccine five or more months ago are more likely to test positive for COVID-19 than people who were fully vaccinated less than five months ago.
• Overall, 1.8% of individulas tested positive in a research including nearly 34,000 fully vaccinated adults in Israel which were tested to see if they had a breakthrough case of COVID-19.
• At all ages, the odds of testing positive were higher when the last vaccine dose was received at least 146 days earlier.
• Among patients older than 60, the odds of a positive test were almost three times higher when 146 days had passed since the second dose.
• "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," he added. "We are planning to continue our research," said coauthor Dr. Eugene Merzon of Leumit Health Services in Israel.
• Israel has already started administering booster shots to people over the age of 60.