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A team of researchers from the CDC COVID-19 Response Team conducted an observational study on 647 adults hospitalized due to COVID-19, 434 of whom were hospitalized during March 31 - June 4 2020, and 213 hospitalized during October 31 - December 31 2020. 91% of all hospitalized patients had at least one risk factor for severe COVID-19 (living in long-term care facilities (LTCFs), aged 65 years or more, or having at least 1 high-risk condition). A significant decrease in hospitalizations among people living in LTCFs was seen in the October-December cohort compared to the March-June group, suggesting that those in high-risk groups be prioritized for COVID-19 vaccination to reduce hospitalizations and prevent mortality.

A multi-center retrospective cohort study conducted by researchers from the CDC COVID-19 Response Team and United States Public Health Service Corps investigated 489,471 pregnant patients who delivered at 703 hospitals between March and September 2020. 6,550 of those patients had confirmed COVID-19, which was associated with increased risk for severe adverse outcomes including ARDS, death, and sepsis, as well as preterm labor with preterm delivery (Table 2), and longer hospitalization time (Figure 1). These findings signify the importance of implementation of mitigation strategies, counseling, and clinical attention to lessen the risk of SARS-CoV-2 infection for pregnant women given the increased risk for adverse events.

A cross-sectional study conducted at the Beijing Institute of Microbiology and Epidemiology assessed blood samples taken from 59 patients who recovered from COVID-19 between 257 and 343 days post-SARS-CoV-2 infection. They found at the designated time point 90% of patients possessed detectable IgG antibodies against the virus spike and nucleocapsid proteins, 60% possessed antibodies against the receptor binding domain (Figure 1), and 70% possessed specific memory B and T cell responses (Figure 2). The findings suggest that immunity against the virus largely persists at about one year after infection, though the small sample size warrants future large-scale studies.

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