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KEYWORDS Pandemic Influenza Disaster preparedness KEY POINTSIn a globalized world where epidemics and pandemics are increasingly common, hospital preparation requires early planning. Infection prevention controls are critical during pandemics to reduce the risk to staff and other patients. In an emergency, ICU capacity may be increased by utilizing alternate hospital sites and non-ICU staff under the supervision of trained critical care personnel. Community engagement during a pandemic is important, to reduce alarm and also to ensure equitable distribution of limited resources.Crit Care Clin 35 (2019) 609-618

Background Comparing humoral responses in SARS-CoV-2 vaccinees, those with SARS-CoV-2 infection, or combinations of vaccine/infection (‘hybrid immunity’), may clarify predictors of vaccine immunogenicity. Methods We studied 2660 U.S. Military Health System beneficiaries with a history of SARS-CoV-2 infection-alone (n = 705), vaccination-alone (n = 932), vaccine-after-infection (n = 869), and vaccine-breakthrough-infection (n = 154). Peak anti-spike-IgG responses through 183 days were compared, with adjustment for vaccine product, demography, and comorbidities. We excluded those with evidence of clinical or sub-clinical SARS-CoV-2 reinfection from all groups. Results Multivariable regression results indicated vaccine-after-infection anti-spike-IgG responses were higher than infection-alone (p < 0.01), regardless of prior infection severity. An increased time between infection and vaccination was associated with a greater post-vaccination IgG response (p < 0.01). Vaccination-alone elicited a greater IgG response, but more rapid waning of IgG (p < 0.01), compared to infection-alone (p < 0.01). BNT162b2 and mRNA-1273 vaccine-receipt was associated with greater IgG responses compared to JNJ-78436735 (p < 0.01), regardless of infection history. Those with vaccine-after-infection or vaccine-breakthrough-infection had a more durable anti-spike-IgG response compared to infection-alone (p < 0.01). Conclusions Vaccine-receipt elicited higher anti-spike-IgG responses than infection-alone, although IgG levels waned faster in those vaccinated (compared to infection-alone). Vaccine-after-infection elicits a greater humoral response compared to vaccine or infection alone; and the timing, but not disease severity, of prior infection predicted these post-vaccination IgG responses. While differences between groups were small in magnitude, these results offer insights into vaccine immunogenicity variations that may help inform vaccination timing strategies.

ImportanceUnderstanding the factors associated with post-COVID conditions is important for prevention.ObjectiveTo identify characteristics associated with persistent post–COVID-19 symptoms and to describe post–COVID-19 medical encounters.Design, Setting, and ParticipantsThis cohort study used data from the Epidemiology, Immunology, and Clinical Characteristics of Emerging Infectious Diseases With Pandemic Potential (EPICC) study implemented in the US military health system (MHS); MHS beneficiaries aged 18 years or older who tested positive for SARS-CoV-2 from February 28, 2020, through December 31, 2021, were analyzed, with 1-year follow-up.ExposuresSARS-CoV-2 infection.Main Outcomes and MeasuresThe outcomes analyzed included survey-reported symptoms through 6 months after SARS-CoV-2 infection and International Statistical Classification of Diseases and Related Health Problems, Tenth Revision diagnosis categories reported in medical records 6 months following SARS-CoV-2 infection vs 3 months before infection.ResultsMore than half of the 1832 participants in these analyses were aged 18 to 44 years (1226 [66.9%]; mean [SD] age, 40.5 [13.7] years), were male (1118 [61.0%]), were unvaccinated at the time of their infection (1413 [77.1%]), and had no comorbidities (1290 [70.4%]). A total of 728 participants (39.7%) had illness that lasted 28 days or longer (28-89 days: 364 [19.9%]; ≥90 days: 364 [19.9%]). Participants who were unvaccinated prior to infection (risk ratio [RR], 1.39; 95% CI, 1.04-1.85), reported moderate (RR, 1.80; 95% CI, 1.47-2.22) or severe (RR, 2.25; 95% CI, 1.80-2.81) initial illnesses, had more hospitalized days (RR per each day of hospitalization, 1.02; 95% CI, 1.00-1.03), and had a Charlson Comorbidity Index score of 5 or greater (RR, 1.55; 95% CI, 1.01-2.37) were more likely to report 28 or more days of symptoms. Among unvaccinated participants, postinfection vaccination was associated with a 41% lower risk of reporting symptoms at 6 months (RR, 0.59; 95% CI, 0.40-0.89). Participants had higher risk of pulmonary (RR, 2.00; 95% CI, 1.40-2.84), diabetes (RR, 1.46; 95% CI, 1.00-2.13), neurological (RR, 1.29; 95% CI, 1.02-1.64), and mental health–related medical encounters (RR, 1.28; 95% CI, 1.01-1.62) at 6 months after symptom onset than at baseline (before SARS-CoV-2 infection).Conclusions and RelevanceIn this cohort study, more severe acute illness, a higher Charlson Comorbidity Index score, and being unvaccinated were associated with a higher risk of reporting COVID-19 symptoms lasting 28 days or more. Participants with COVID-19 were more likely to seek medical care for diabetes, pulmonary, neurological, and mental health–related illness for at least 6 months after onset compared with their pre-COVID baseline health care use patterns. These findings may inform the risk-benefit ratio of COVID-19 vaccination policy.