Breakthrough infections, cardiovascular effects of COVID-19, pandemic mental health

Two new studies provided details on breakthrough infections. A July 30 report from Morbidity and Mortality Weekly Report described 469 cases of COVID-19 that were identified in July in a town in Barnstable County, Mass. Most cases (74%) occurred in fully vaccinated people, and 79% of the vaccinated patients were symptomatic. Genomic sequencing of specimens from 133 patients found Delta variants in 120. Of the five patients who were hospitalized, four were fully vaccinated. No deaths were reported. The authors cautioned that “Data from this report are insufficient to draw conclusions about the effectiveness of COVID-19 vaccines against SARS-CoV-2, including the Delta variant, during this outbreak” but recommended that event organizers and health authorities “continually assess the need for additional measures, including limiting capacity at gatherings or event postponement, based on current rates of COVID-19 transmission, population vaccination coverage, and other factors.” An accompanying statement by the CDC director said the findings were concerning and “a pivotal discovery leading to CDC's updated mask recommendation.”

The second study, published by the New England Journal of Medicine on July 28, was conducted in January to April and included 1,497 Israeli health care workers who had been fully vaccinated with the Pfizer-BioNTech vaccine. A total of 39 breakthrough infections were identified by testing based on symptoms or exposure to COVID-19. Lower neutralizing antibody titers were found in infected study participants compared to controls and were associated with higher infectivity, “consistent with the hypothesis that the neutralizing antibody titer after vaccination is a marker of overall immune response,” the authors noted. Most of the breakthrough cases were mild or asymptomatic, although 19% had persistent symptoms; 85% of samples tested contained the Alpha variant of COVID-19. The authors concluded that the results show the vaccine is “extremely effective” but also that “Rare breakthrough infections carry an infectious potential and create a special challenge, since such infections are often asymptomatic and may pose a risk to vulnerable populations.”

COVID-19 patients have increased risk of myocardial infarction and stroke in the first weeks after infection, according to a study published by The Lancet on July 29. It compared 86,742 patients with COVID-19 to 348,481 matched controls, all in Sweden, and found that the incidence rate ratios for myocardial infarction and stroke were more than doubled in the first two weeks after COVID-19 infection. The risk remained elevated in weeks 3 and 4 after infection, although to a lesser extent. “Our study encompasses the whole first wave of the COVID-19 outbreak in Sweden,” the authors noted. “Our results indicate that acute cardiovascular complications might represent an essential clinical manifestation of COVID-19 and the long-term effects might be a challenge for the future.”

The effects of the pandemic on Americans' mental health were described in another new study, published by the Journal of General Internal Medicine on July 27. Surveyed online in January, 18.3% of 2,023 Michigan residents ages 50 to 80 years reported their mental health to be worse than it was before the pandemic, with higher rates among respondents who were women, had a bachelor's degree, or rated their health as fair to poor. In addition, 18.7% of those surveyed reported worse sleep, 18.9% worse depression, and 28.3% worse anxiety. The survey also asked what strategies, if any, they had used since March 2020 to help address their mental health: 29.0% made a lifestyle change, 12.7% discussed a mental health concern with their primary care clinician, 5.4% started seeing a mental health clinician, and 5.6% adjusted or started a new medication. “Given the increase in mental health symptoms during the pandemic, screening for symptoms and ensuring accessible treatment, including through telehealth, are essential even as the pandemic improves,” the study authors concluded.

Finally, two experts made the case for mandatory COVID-19 vaccination of health care workers in an Ideas and Opinions piece published by Annals of Internal Medicine on July 30. “There are ethical, legal, and practical reasons for health care workers to be vaccinated against COVID-19,” they wrote, noting that as of July 29, 88 professional societies and organizations had signed on to a joint statement supporting mandatory vaccination of health care workers. ACP announced its support for the statement on July 26.