New research on mixed vaccine boosters, long-term outcomes, omicron severity

Mixing and matching the authorized COVID-19 vaccines appears safe and effective, according to a study published by the New England Journal of Medicine on Jan. 26. It included 154 patients who got a Moderna booster, 150 who got a Johnson & Johnson (Janssen) booster, and 153 who got the Pfizer-BioNTech vaccine as a booster. More than half of the recipients reported having injection-site pain, malaise, headache, or myalgia. With the boosters, their antibody neutralizing titers against SARS-CoV-2 increased by a factor of 4 to 73, and binding titers increased by a factor of 5 to 55. “Homologous boosting provided a wide range of immunogenicity responses, and heterologous boosting provided similar or higher levels,” the authors said. “These data suggest that an immune response will be generated for each of these vaccines used as a booster regardless of the primary Covid-19 vaccination regimen.”

Two studies reported one-year outcomes of patients with COVID-19. A Dutch study, published by JAMA on Jan. 24, included 246 patients who required ICU treatment and completed a questionnaire at one-year follow-up. Physical symptoms were reported by 74.3%, mental symptoms by 26.2%, and cognitive symptoms by 16.2%. The most frequent physical problems were weakened condition, joint stiffness or pain, muscle weakness, and myalgia. The authors noted that recent research on ICU survivors who didn't have COVID-19 has reported similar prevalence of physical and cognitive symptoms and a higher rate of mental symptoms. The other study, published by the Journal of General Internal Medicine on Jan. 24, included 530 U.S. patients who were either treated in an ED or hospitalized for COVID-19. Overall, 41.5% reported worse health compared to a year prior and 44.2% reported persistent symptoms. Women, patients who had required mechanical ventilation, and people with HIV were significantly more likely to report persistent symptoms. The authors concluded that such symptoms “are broadly distributed, are not limited to one specific patient group, and appear to be unrelated to age.”

The omicron variant period has seen unprecedented numbers of COVID-19 cases and hospitalizations but lower severity of illness than in winter 2020 to 2021 or during the delta variant period, according to a study published by MMWR on Jan. 25. It found that with omicron, a maximum of 20.6% of staffed inpatient beds were in use for COVID-19 patients, more than in either comparison period. However, the percentage of hospitalized COVID-19 patients admitted to an ICU during omicron was 13.0%, compared to 18.8% during the winter of 2020-2021 and 17.5% during delta. The percentages of patients who received invasive mechanical ventilation or died while in the hospital were also lowest during omicron (3.5% vs. 7.5% vs. 6.6% and 7.1% vs. 12.9% vs. 12.3%, respectively), as was length of hospital stay (5.5 days vs. 8.0 days vs. 7.6 days). “COVID-19 disease severity appears to be lower during the Omicron period than during previous periods of high transmission, likely related to higher vaccination coverage, which reduces disease severity, lower virulence of the Omicron variant, and infection-acquired immunity,” the authors wrote. They also noted that by the week ending Jan. 15, ED visits appeared to be decreasing, and the rapid increase in cases and hospital admissions was slowing.

The FDA announced two recent policy changes for outpatient COVID-19 treatment. On Jan. 24, the agency revised the authorizations for two monoclonal antibody treatments—bamlanivimab and etesevimab and casirivimab and imdevimab—to limit their use to patients with a variant that is susceptible to these treatments. Given the predominance of the omicron variant, which is not susceptible, that meant that the antibodies are not authorized for use in any U.S. states, territories, and jurisdictions, a press release noted. On Jan. 21, the FDA expanded the indications for remdesivir to include patients with a positive SARS-CoV-2 viral test who are not hospitalized and have mild to moderate COVID-19 and are at high risk for progression to severe disease.

Finally, the American Heart Association and collaborating organizations updated interim guidance on providing cardiac life support to patients with COVID-19. Changes include that the guidance now calls on clinicians to don personal protective equipment before beginning resuscitation, whereas before it recommended initiation of resuscitation be the first priority. An editorial published along with the guidance in Circulation: Cardiovascular and Outcomes on Jan. 24 observed that some frontline clinicians will still make their own decisions in this situation and that the interim guidance will likely change again based on emerging evidence.