CDC reports that almost a million people have already received booster doses, the European Union successfully vaccinated 70% of its adult population, and more in this week's roundup of Covid-19 news.

• According to a new study published in JAMA, Moderna's Covid-19 vaccine produces more than twice as many antibodies as Pfizer-BioNTech's. In the study, researchers examined 1,647 fully vaccinated health care workers in Belgium, including 688 who received two doses of Moderna's vaccine, and 959 who received two doses of Pfizer-BioNTech's vaccine. The researchers found that those who received Moderna's vaccine had higher antibody levels than workers who received Pfizer-BioNTech's vaccine. In addition, they found that previous infection increased antibody levels among those who had been vaccinated, regardless of which vaccine they received. Specifically, Moderna recipients averaged antibody levels of 2,881 units per milliliter for those without previous infection, and 3,836 units per milliliter for those who previously had Covid-19. In contrast, Pfizer-BioNTech recipients averaged antibody levels of 1,108 units per milliliter for those without previous infection, and 1,444 units per milliliter for those who previously had Covid-19. According to the researchers, the difference in antibody levels could be attributed to the Moderna vaccine's higher concentration of mRNA and the longer interval between Moderna doses, which is four weeks compared to three weeks for the Pfizer-BioNTech vaccine, The Hill reports. (Coleman, The Hill, 8/31)

• According to CDC, about 955,000 people have received a booster dose of either the Pfizer-BioNTech or Moderna Covid-19 vaccine after FDA authorized additional doses for the immunocompromised last month. The agency said this number includes people who were previously fully vaccinated with two doses of Pfizer-BioNTech's or Moderna's vaccines, or one dose of Johnson & Johnson's vaccine. However, according to CNBC, it is not clear whether all individuals who received a booster dose were considered immunocompromised. Judy Persichilli, New Jersey's state health commissioner, said the state is currently working to identify more people who qualify for an additional dose. "Nationally we think about 3% of the population is immunocompromised," she said, "so we're really asking particularly medical directors in long-term care to do a deep analysis of those medical records and identify individuals who should be queued up to get that third dose right now." (Lovelace Jr., CNBC, 8/31)

• The European Union (EU) on Tuesday hit its target of fully vaccinating 70% of adults against the coronavirus, The Hill reports. Stella Kyriakides, the European commissioner for health and food safety, said, "This is a collective achievement of the EU and its Member States that shows what is possible when we work together with solidarity and in coordination. Our efforts to further increase vaccinations across the EU will continue unabated." According to The Hill, meeting the 70% threshold means that 256 million people across the EU's member countries have been fully vaccinated. In contrast, only 52% of the total U.S. population and 63% of adults have been fully vaccinated against the coronavirus, according to CDC data. (Lonas, The Hill, 8/31)

• According to Becker's Hospital Review, a new study published in CDC's Morbidity and Mortality Weekly Report found that Covid-19 patients are 15.7 times more likely to develop myocarditis than patients without Covid-19, with risk varying by age and sex. For the study, researchers examined data from March to January from the Premier Healthcare Database Special Covid-19 Release, an administrative database of health care encounters from more than 900 hospitals. Overall, the researchers found that while myocarditis was uncommon among Covid-19 patients, there was a significant association between the two diagnoses. Specifically, Covid-19 patients had a 0.146% risk of myocarditis while patients without Covid-19 had a 0.009% risk. In addition, the researchers found that the risk of myocarditis was higher among men than women and highest among adults ages 75 or older. And according to STAT News' "Morning Rounds," the study's results indicate that there is a higher risk of heart muscle inflammation with having had Covid-19 compared to having been vaccinated against it. (Masson, Becker's Hospital Review, 8/31; Cooney, "Morning Rounds," STAT News, 9/1)

• An observational study from Mayo Clinic found that monoclonal antibody treatments using casirivimab and imdevimab are effective at keeping high-risk Covid-19 patients from being hospitalized, Becker's Hospital Review reports. The study involved almost 1,400 patients, 696 of whom received the antibody treatment between December 2020 and April 2021. Each patient was evaluated 14, 21, and 28 days after treatment was administered. The researchers found that at the 14-day mark, 1.3% of patients who received the treatment were hospitalized compared to 3.3% of patients who had not received the treatment. At the 21-day mark, the hospitalization rate remained the same in the treated group while the hospitalization rate in the untreated group increased to 4.2%. Finally, at the 28-day mark, 1.6% of the treated patients had been hospitalized compared to 4.8% of the untreated patients. Overall, patients who received the antibody treatment experienced a 60% to 70% relative reduction in hospitalization. Raymond Razonable, an infectious diseases specialist at Mayo Clinic and the study's senior author, said, "Once again, this real-world study suggests that when patients who are at high risk due to a range of comorbidities contract a mild or moderate case of Covid-19, this combination of monoclonal injections gives them a chance of a non-hospitalized recovery. In other words, they recover safely at home." (Robertson, Becker's Hospital Review, 8/31; Nellis, Mayo Clinic News Network, 8/30)