Second wave mortality among patients hospitalised for COVID-19 in Sweden: a nationwide observational cohort study

Abstract

Background During the first pandemic wave, a substantial decline in mortality was seen among hospitalized COVID-19 patients. We aimed to study if the decreased mortality continued during the second wave, using data compiled by the Swedish National Board of Health and Welfare. Method Retrospective nationwide observational study of all patients hospitalized in Sweden between March 1st and December 31st, 2020, with SARS-CoV-2 RNA positivity 14 days before to 5 days after admission and a discharge code for COVID-19. Outcome was 60-day all-cause mortality. Poisson regression was used to estimate the relative risk (RR) for death by month of admission, adjusting for age, sex, socioeconomic data, comorbidity, care dependency, and country of birth. Findings A total of 32 452 patients were included. December had the highest number of admissions/month (n=8253) followed by April (n=6430). The 60-day crude mortality decreased from 24.7% (95% CI, 23.0%-26.5%) for March to 10.4% (95% CI, 8.9%-12.1%) for July-September (as reported previously), later increased to 19.9% (95% CI, 19.1-20.8) for December. RR for 60-day death for December (reference) was higher than those for June to November (RR ranging from 0.74 to 0.89; 95% CI <1 for all months). SARS-CoV-2 variants of concern were only sporadically found in Sweden before January 2021. Interpretation The decreased mortality of hospitalized COVID-19 patients after the first wave turned and increased during the second wave.

Temporal trends in hospitalizations and 30-day mortality in older patients during the COVID pandemic from March 2020 to July 2021

“…Several studies, including our previous study, have noted a decrease in mortality throughout the first wave of the pandemic 22 1 . A subsequent increase was observed again during the second wave in Sweden 9, 23 . One study included more than 30,000 COVID-19 patients (including those admitted to the ICU) hospitalized between March and December 2020 in Sweden and showed that the 60-day case fatality rate for hospitalized cases decreased in the first wave but increased again in the second wave 9 .…”

“…[4][5][6][7] In previous reports, COVID-19 mortality in hospitalized patients in Sweden increased with each pandemic wave and decreased between pandemic peaks. 8,9 According to the Swedish Board of Health and Welfare, 60-day mortality after admission with COVID-19 decreased from a first-wave peak in March 2020 (25%) to a first nadir in August-September 2020 (10%), then rose again but to lower levels as the second wave progressed to a peak in December 2020 (20%), decreasing steadily afterwards. 10 Decreasing mortality during the first pandemic wave was also observed in studies from the US, 11 with subsequent increases in mortality during pandemic surges.…”

Decreased Mortality Over Time During the First Wave in Patients With COVID-19 in Geriatric Care: Data From the Stockholm GeroCovid Study

“…In addition, the decrease in mortality may have at least partially followed the decrease of infection in the community, taking pressure off the health care system and permitting the admission of patients with milder disease: in a preepeer review retrospective study of hospital admissions in Sweden, 60-day mortality decreased in the first wave following by an increase in the second wave. 25,26 This suggests that the mortality decrease in the first wave was not only due to improvements in care.…”

Long-lasting humoral immunity in Covid-19 infected patients at a University Hospital Clinic in Östergötland County Council during 2020-2021

“…For respiratory tract infections such as influenza and RSV this is well documented (4)(5)(6). It is thus very likely so also with the Covid-19 infectious virus, the betacoronavirus SARS CoV-2 (7)(8)(9)(10)(11)12). And this is the reason for conducting this study.…”