Background Protection afforded from prior disease among patients with coronavirus disease 2019 (COVID-19) infection is unknown. If infection provides substantial long-lasting immunity, it may be appropriate to reconsider vaccination distribution plans. Methods This retrospective cohort study of one multi-hospital health system included 150,325 patients tested for COVID-19 infection via PCR from March 12, 2020 to August 30, 2020. Testing performed up to February 24, 2021 in these patients was included for analysis. The main outcome was reinfection, defined as infection ≥ 90 days after initial testing. Secondary outcomes were symptomatic infection and protection of prior infection against reinfection. Results Of 150,325 patients, 8,845 (5.9%) tested positive and 141,480 (94.1%) tested negative prior to August 30. 1,278 (14.4%) of the positive patients were retested after 90 days, and 62 had possible reinfection. Of those, 31 (50%) were symptomatic. Of those with initial negative testing, 5,449 (3.9%) were subsequently positive and 3,191 of those (58.5%) were symptomatic. Protection offered from prior infection was 81.8% (95% confidence interval 76.6 to 85.8), and against symptomatic infection was 84.5% (95% confidence interval 77.9 to 89.1). This protection increased over time. Conclusions Prior infection in patients with COVID-19 was highly protective against reinfection and symptomatic disease. This protection increased over time, suggesting that viral shedding or ongoing immune response may persist beyond 90 days and may not represent true reinfection. As vaccine supply is limited, patients with known history of COVID-19 could delay early vaccination to allow for the most vulnerable to access the vaccine and slow transmission.

Background Infection with SARS-CoV-2 has been shown to be highly protective against reinfection and symptomatic disease. However, effectiveness against the highly transmissible Delta variant and duration of natural immunity remain unknown. Methods This retrospective cohort study included 325,157 patients tested for coronavirus disease 2019 (COVID-19) via polymerase chain reaction (PCR) from 09 March 2020 to 31 December 2020 (Delta variant analysis) and 152,656 patients tested from 09 March 2020 to 30 August 2020 (long-term effectiveness analysis) with subsequent testing through 09 September 2021. The primary outcome was reinfection, defined as a positive PCR test >90 days after initial positive test. Results Among 325,157 patients tested before 31 December 2020, 50,327 (15.5%) tested positive. After 01 July 2021 (Delta dominant period), 40 (0.08%) of the initially positive and 1,494 (0.5%) of the initially negative patients tested positive. Protection of prior infection against reinfection with Delta was 85.4% (95% CI, 80.0-89.3). For the long-term effectiveness analysis, among 152,656 patients tested before 30 August 2020, 11,186 (7.3%) tested positive. After at least 90 days, 81 (0.7%) of the initially positive patients and 7,167 (5.1%) of the initially negative patients tested positive. Overall protection of previous infection was 85.7% (95% CI, 82.2-88.5) and lasted up to 13 months. Patients over age 65 had slightly lower protection. Conclusions SARS-CoV-2 infection is highly protective against reinfection with the Delta variant. Immunity from prior infection lasts for at least 13 months. Countries facing vaccine shortages should consider delaying vaccinations for previously infected patients to increase access.

IMPORTANCE Despite high prevalence of elevated blood pressure (BP) among medical inpatients, BP management guidelines are lacking for this population. The outcomes associated with intensifying BP treatment in the hospital are poorly studied.OBJECTIVES To characterize clinician response to BP in the hospital and at discharge and to compare short-and long-term outcomes associated with antihypertensive treatment intensification.DESIGN, SETTING, AND PARTICIPANTS This cohort study took place from January 1 to December 31, 2017, with 1 year of follow-up at 10 hospitals within the Cleveland Clinic Hospitals health care system. All adults admitted to a medicine service in 2017 were evaluated for inclusion. Patients with cardiovascular diagnoses were excluded. Demographic and BP characteristics were used for propensity matching.EXPOSURES Acute hypertension treatment, defined as administration of an intravenous antihypertensive medication or a new class of an oral antihypertensive treatment. MAIN OUTCOMES AND MEASURESThe association between acute hypertension treatment and subsequent inpatient acute kidney injury, myocardial injury, and stroke was measured. Postdischarge outcomes included stroke and myocardial infarction within 30 days and BP control up to 1 year. RESULTS Among 22 834 adults hospitalized for noncardiovascular diagnoses (mean [SD] age, 65.6 [17.9] years; 12 993 women [56.9%]; 15 963 White patients [69.9%]), 17 821 (78%) had at least 1 hypertensive BP recorded during their admission. Of these patients, 5904 (33.1%) were treated. A total of 8692 of 106 097 cases (8.2%) of hypertensive systolic BPs were treated; of these, 5747 (66%) were treated with oral medications. In a propensity-matched sample controlling for patient and BP characteristics, treated patients had higher rates of subsequent acute kidney injury (466 of 4520 [10.3%] vs 357 of 4520 [7.9%]; P < .001) and myocardial injury (53 of 4520 [1.2%] vs 26 of 4520 [0.6%]; P = .003). There was no BP interval in which treated patients had better outcomes than untreated patients. A total of 1645 of 17 821 patients (9%) with hypertension were discharged with an intensified antihypertensive regimen. Medication intensification at discharge was not associated with better BP control in the following year. CONCLUSIONS AND RELEVANCEIn this cohort study, hypertension was common among medical inpatients, but antihypertensive treatment intensification was not. Intensification of therapy without signs of end-organ damage was associated with worse outcomes.