Type 1 diabetes mellitus and SARS‐CoV‐2 in pediatric and adult patients – Data from the DPV network

BackgroundData on patients with type 1 diabetes mellitus (T1DM) and severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infections are sparse. This study aimed to investigate the association between SARS‐CoV‐2 infection and T1DM.MethodsData from the Prospective Diabetes Follow‐up (DPV) Registry were analyzed for diabetes patients tested for SARS‐CoV‐2 by polymerase chain reaction (PCR) in Germany, Austria, Switzerland, and Luxembourg during January 2020–June 2021, using Wilcoxon rank‐sum and chi‐square tests for continuous and dichotomous variables, adjusted for multiple testing.ResultsData analysis of 1855 pediatric T1DM patients revealed no differences between asymptomatic/symptomatic infected and SARS‐CoV‐2 negative/positive patients regarding age, new‐onset diabetes, diabetes duration, and body mass index. Glycated hemoglobin A1c (HbA1c) and diabetic ketoacidosis (DKA) rate were not elevated in SARS‐CoV‐2‐positive vs. ‐negative patients. The COVID‐19 manifestation index was 37.5% in individuals with known T1DM, but 57.1% in individuals with new‐onset diabetes. 68.8% of positively tested patients were managed as outpatients/telemedically. Data analysis of 240 adult T1MD patients revealed no differences between positively and negatively tested patients except lower HbA1c. Of these patients, 83.3% had symptomatic infections; 35.7% of positively tested patients were hospitalized.ConclusionsOur results indicate low morbidity in SARS‐CoV‐2‐infected pediatric T1DM patients. Most patients with known T1DM and SARS‐CoV‐2 infections could be managed as outpatients. However, SARS‐CoV‐2 infection was usually symptomatic if it coincided with new‐onset diabetes. In adult patients, symptomatic SARS‐CoV‐2 infection and hospitalization were associated with age.     

Pronounced antibody elevation after SARS‐CoV‐2 BNT162b2 mRNA booster vaccination in nursing home residents

BackgroundInfection control during COVID‐19 outbreaks in nursing facilities is a critical public health issue. Antibody responses before and after the third (booster) dose of SARS‐CoV‐2 vaccination in nursing home residents have not been fully characterized.MethodsThis study included 117 individuals: 54 nursing home residents (mean age, 83.8 years; 39 SARS‐CoV‐2‐naive and 15 previously infected) and 63 healthcare workers (mean age, 45.8 years; 32 SARS‐CoV‐2‐naive and 31 previously infected). Anti‐spike (receptor‐binding domain [RBD]) and anti‐nucleocapsid antibody responses to BNT162b2 mRNA vaccination and their related factors were evaluated using pre‐ (shortly and 6 months after the second dose) and post‐booster vaccination samples.ResultsThe median anti‐spike (RBD) IgG level in SARS‐CoV‐2‐naive residents 6 months after the second dose was the lowest among the four groups, with a decreasing rate of over 90%. The median rate of increase before and after the third dose in SARS‐CoV‐2‐naive residents was significantly higher than that in SARS‐CoV‐2‐naive healthcare workers (64.1‐ vs. 37.0‐fold, P = 0.003), with the highest level among the groups. The IgG ratio of SARS‐CoV‐2‐naive residents to healthcare workers after the second and third doses changed from one‐fifth (20%) to one‐half (50%). The rate of increase after the third dose in previously infected individuals was three‐ to fourfold, regardless of residents or healthcare workers.ConclusionsAdvanced aged nursing home residents, poor responders in the initial SARS‐CoV‐2 vaccine series, could obtain sufficient antibody responses with the additional booster dose, despite more than 6 months after the second.     

SARS‐CoV‐2 infection rate in Antananarivo frontline health care workers,Madagascar

BackgroundHealth care workers (HCWs) represent a vulnerable population during epidemic periods. Our cohort study aimed to estimate the risk of infection and associated factors among HCWs during the first wave of severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) in Madagascar.MethodsA prospective cohort study was carried out in three hospitals that oversaw the first cases of COVID‐19. Monthly ELISA‐based serological tests were conducted, and nasopharyngeal swabs were collected in the case of symptoms linked to COVID‐19 for RT–PCR analysis. Survival analyses were used to determine factors associated with SARS‐CoV‐2 infection.ResultsThe study lasted 7 months from May 2020. We included 122 HCWs, 61.5% of whom were women. The median age was 31.9 years (IQR: 26.4–42.3). In total, 42 (34.4%) had SARS‐CoV‐2 infections, of which 20 were asymptomatic (47.6%). The incidence of SARS‐CoV‐2 infection was 9.3% (95% CI [6.5–13.2]) person‐months. Sixty‐five HCWs presented symptoms, of which 19 were positive by RT–PCR. When adjusted for exposure to deceased cases, infection was more frequent in HCWs younger than 30 years of age (RR = 4.9, 95% CI [1.4–17.2]).ConclusionOur results indicate a high incidence of infection with SARS‐CoV‐2 among HCWs, with a high proportion of asymptomatic cases. Young HCWs are more likely to be at risk than others. Greater awareness among young people is necessary to reduce the threat of infection among HCWs.     

The evaluation of an automated mariPOC SARS‐CoV‐2 antigen test compared to RT‐qPCR SARS‐CoV‐2 assay and comparison of its sensitivity in Delta‐ and Omicron‐variant samples

BackgroundThe rapid diagnostics tests for SARS‐CoV‐2 antigen vary in their sensitivities, and moreover, genomic mutations may further affect the performance of the assays. We aimed to evaluate the analytical performance of an automated antigen assay and compare its sensitivity in Delta‐ and Omicron‐variant positive clinical samples.Material and methodsThe analytical performance of an automated mariPOC SARS‐CoV‐2 antigen test was evaluated on a population of community‐dwelling subjects with mild respiratory symptoms or being asymptomatic investigated by the RT‐qPCR Allplex™ SARS‐CoV‐2 assay. The sensitivity and specificity of the antigen test were evaluated on prospective 621 nasopharyngeal swabs along with oropharyngeal swabs. The sensitivity regarding variants determined by the Allplex™ SARS‐CoV‐2 Variant assays was analysed in additional, retrospective 158 Delta and 59 Omicron samples.ResultsThe overall sensitivity of the antigen test in prospective samples was 77.9% (113/145; 95% confidence interval [CI] 70.3–84.4) with the specificity of 99.8% (95% CI 98.8–100). Regarding the variant, the sensitivity was higher in Omicron‐variant samples, 93.2% (55/59; 95% CI 83.5–98.1), compared to Delta‐variant samples, 71.5% (113/158; 95% CI 63.8–78.4; p = .001).ConclusionIn community‐dwelling subjects with mild respiratory symptoms or being asymptomatic, the automated mariPOC SARS‐CoV‐2 antigen test showed high sensitivity over 98.0% in subgroup samples with cycle threshold (Ct) values < 25. Regarding the variant, the antigen test sensitivity was higher in the Omicron‐variant samples compared to the Delta‐variant samples. The analytical performance of the antigen test can differ between the SARS‐CoV‐2 variants, and a re‐evaluation should be performed for new circulating lineages.     

SARS‐CoV‐2 infections in households in a peri‐urban community of Lima,Peru: A prospective cohort study

BackgroundWe assessed the prevalence and incidence of SARS‐CoV‐2 infections in a prospective study of households in Lima, Peru.MethodsHouseholds with a child, a young adult 18–50 years, and an adult age >50 years in peri‐urban Lima were followed with twice‐a‐week household visits during a 2‐month period. Nasal swabs and saliva specimens were collected twice weekly, and nasopharyngeal swabs were collected weekly from each participant, regardless of symptoms. Laboratory‐confirmed SARS‐CoV‐2 infection was defined by two RT‐PCR tests from any of the collected specimens within a week. Blood samples collected at enrollment and end of follow‐up were tested with rapid serological tests. We calculated the prevalence and incidence of laboratory‐confirmed SARS‐CoV‐2 infections.ResultsWe enrolled 132 participants from 44 households: 44 children, 44 young adults, and 44 older adults. A total of 13 SARS‐CoV‐2 infections were detected in eight households, for an overall period prevalence of 9.85% (95% confidence interval [CI]: 5.35–16.25). Most (61.54%) infections were symptomatic. Eight of 11 (72.73%) SARS‐CoV‐2 detections corresponded to the Lambda variant. During 218.79 person‐months at risk of follow‐up, there were six new SARS‐CoV‐2 infections detected (2.74 per 100 person‐month, 95% CI: 1.25–6.04). At enrollment, 59 of 128 participants tested had positive SARS‐CoV‐2 IgG serology (46.09%, 95% CI: 37.25–55.12). Five of six new infections occurred among participants with negative baseline serology.ConclusionsWe demonstrated high incidence of SARS‐CoV‐2 infections in households, especially among subjects without evidence of prior infection, most of them not detected by the Ministry of Health system.     

SARS‐CoV‐2 re‐infection versus prolonged shedding: A case series

Since the start of the SARS‐CoV‐2 pandemic, it has been difficult to differentiate between SARS‐CoV‐2 re‐infection and prolonged RNA shedding. In this report, we identified patients with positive RT‐PCR results for SARS‐CoV‐2 ≥70 days apart. Clinical and laboratory data were collected and criteria were applied to discern whether the presentation was consistent with SARS‐CoV‐2 re‐infection or prolonged viral RNA shedding. Eleven individuals met the initial testing criteria, of which, seven met at least one criteria for re‐infection and four were consistent with prolonged RNA shedding. These data demonstrate the need for criteria to differentiate SARS‐CoV‐2 re‐infection from prolonged RNA shedding.     

Point‐of‐care testing for influenza in a university emergency department: A prospective study

BackgroundSeasonal influenza is a burden for emergency departments (ED). The aim of this study was to investigate whether point‐of‐care (POC) PCR testing can be used to reduce staff sick days and improve diagnostic and therapeutic procedures.ObjectivesThe aim of this study was to investigate whether point‐of‐care (POC) PCR testing can be used to reduce staff sick days and improve diagnostic and therapeutic procedures.MethodsUsing a cross‐over design, the cobas® Liat® Influenza A/B POC PCR test (Liat) was compared with standard clinical practice during the 2019/2020 influenza season. All adult patients (aged ≥ 18 years) with fever (≥38°C) and respiratory symptoms were included. Primary end points were the prevalence of influenza infections in the ED and staff sick days. Secondary end points were frequency of antiviral and antibacterial therapy, time between admission and test result or treatment initiation, patient disposition, ED length of stay (LOS), and for inpatients mortality and LOS. Nurses were interviewed about handling and integration of POC testing. The occurrence of SARS‐CoV‐2 infections coincided with the second half of the study.ResultsA total of 828 patients were enrolled in the study. All 375 patients of the intervention group were tested with Liat, and 103 patients of them (27.6%) tested positive. During the intervention period, staff sick days were reduced by 34.4% (P = .023). Significantly, more patients in the intervention group received antiviral therapy with neuraminidase inhibitors (7.2% vs 3.8%, P = .028) and tested patients received antibiotics more frequently (40.0% vs 31.6%, P = .033). Patients with POC test were transferred to external hospitals significantly more often (5.6% vs 1.3%, P = .01).ConclusionWe conclude that POC testing for influenza is useful in the ED, especially if it is heavily frequented by patients with respiratory symptoms.     

The COVID‐19 epidemic in Madagascar: clinical description and laboratory results of the first wave,march‐september 2020

BackgroundFollowing the first detection of SARS‐CoV‐2 in passengers arriving from Europe on 19 March 2020, Madagascar took several mitigation measures to limit the spread of the virus in the country.MethodsNasopharyngeal and/or oropharyngeal swabs were collected from travellers to Madagascar, suspected SARS‐CoV‐2 cases and contact of confirmed cases. Swabs were tested at the national reference laboratory using real‐time RT‐PCR. Data collected from patients were entered in an electronic database for subsequent statistical analysis. All distribution of laboratory‐confirmed cases were mapped, and six genomes of viruses were fully sequenced.ResultsOverall, 26,415 individuals were tested for SARS‐CoV‐2 between 18 March and 18 September 2020, of whom 21.0% (5,553/26,145) returned positive. Among laboratory‐confirmed SARS‐CoV‐2–positive patients, the median age was 39 years (IQR: 28‐52), and 56.6% (3,311/5,553) were asymptomatic at the time of sampling. The probability of testing positive increased with age with the highest adjusted odds ratio of 2.2 [95% CI: 1.9‐2.5] for individuals aged 49 years and more. Viral strains sequenced belong to clades 19A, 20A and 20B indicative of several independent introduction of viruses.ConclusionsOur study describes the first wave of the COVID‐19 in Madagascar. Despite early strategies in place Madagascar could not avoid the introduction and spread of the virus. More studies are needed to estimate the true burden of disease and make public health recommendations for a better preparation to another wave.     

Symptoms and recovery among adult outpatients with and without COVID‐19 at 11 healthcare facilities—July 2020, United States

BackgroundSymptoms of mild COVID‐19 illness are non‐specific and may persist for prolonged periods. Effects on quality of life of persistent poor physical or mental health associated with COVID‐19 are not well understood.MethodsAdults aged ≥18 years with laboratory‐confirmed COVID‐19 and matched control patients who tested negative for SARS‐CoV‐2 infection at outpatient facilities associated with 11 medical centers in the United States were interviewed to assess symptoms, illness duration, and health‐related quality of life. Duration of symptoms, health‐related quality of life measures, and days of poor physical health by symptoms experienced during illness were compared between case patients and controls using Wilcoxon rank‐sum tests. Symptoms associated with COVID‐19 case status were evaluated by multivariable logistic regression.ResultsAmong 320 participants included, 157 were COVID‐19 cases and 163 were SARS‐CoV‐2 negative controls. Loss of taste or smell was reported by 63% of cases and 6% of controls and was strongly associated with COVID‐19 in logistic regression models (adjusted odds ratio [aOR] = 32.4; 95% confidence interval [CI], 12.6‐83.1). COVID‐19 cases were more likely than controls to have experienced fever, body aches, weakness, or fatigue during illness, and to report ≥1 persistent symptom more than 14 days after symptom onset (50% vs 32%, P < .001). Cases reported significantly more days of poor physical health during the past 14 days than controls (P < .01).ConclusionsDifferentiating COVID‐19 from other acute illnesses will require widespread diagnostic testing, especially during influenza seasons. Persistent COVID‐19‐related symptoms may negatively affect quality of life, even among those initially presenting with mild illness.     

Predictors of all‐cause mortality among patients hospitalized with influenza,respiratory syncytial virus,or SARS‐CoV‐2

BackgroundShared and divergent predictors of clinical severity across respiratory viruses may support clinical and community responses in the context of a novel respiratory pathogen.MethodsWe conducted a retrospective cohort study to identify predictors of 30‐day all‐cause mortality following hospitalization with influenza (N = 45,749; 2010‐09 to 2019‐05), respiratory syncytial virus (RSV; N = 24 345; 2010‐09 to 2019‐04), or severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2; N = 8988; 2020‐03 to 2020‐12; pre‐vaccine) using population‐based health administrative data from Ontario, Canada. Multivariable modified Poisson regression was used to assess associations between potential predictors and mortality. We compared the direction, magnitude, and confidence intervals of risk ratios to identify shared and divergent predictors of mortality.ResultsA total of 3186 (7.0%), 697 (2.9%), and 1880 (20.9%) patients died within 30 days of hospital admission with influenza, RSV, and SARS‐CoV‐2, respectively. Shared predictors of increased mortality included older age, male sex, residence in a long‐term care home, and chronic kidney disease. Positive associations between age and mortality were largest for patients with SARS‐CoV‐2. Few comorbidities were associated with mortality among patients with SARS‐CoV‐2 as compared with those with influenza or RSV.ConclusionsOur findings may help identify patients at greatest risk of illness secondary to a respiratory virus, anticipate hospital resource needs, and prioritize local prevention and therapeutic strategies to communities with higher prevalence of risk factors.     

Risk of symptomatic COVID‐19 due to aircraft transmission: a retrospective cohort study of contact‐traced flights during England’s containment phase

BackgroundKnowledge gaps remain regarding SARS‐CoV‐2 transmission on flights. We conducted a retrospective cohort study to estimate risk of acquiring symptomatic SARS‐CoV‐2 on aircraft, to inform contact tracing and infection control efforts.MethodsWe identified co‐passengers of infectious passengers on 18 England‐bound flights from European cities up to 12/03/2020, using manifests received for contact tracing. Infectious passengers were laboratory‐confirmed cases with symptom onset from 7 days before to 2 days after the flight. Possible aircraft‐acquired cases were laboratory‐confirmed with onset 3‐14 days post‐flight with no known non‐flight exposure. Manifests was merged with the national case management dataset (identifying cases, onset dates, contact tracing status) and the national COVID‐19 linelist. Contact tracing notes were reviewed to identify non‐flight exposures. We calculated attack rates (ARs) among all co‐passengers and within subgroups, including by distance from infectious cases and number of infectious cases on‐board.ResultsThere were 55 infectious passengers and 2313 co‐passengers, including 2221 flight‐only contacts. Five possible aircraft‐acquired cases were identified; ARs of 0.2% (95%CI 0.1‐0.5) among all flight‐only contacts and 3.8% (95%CI 1.3‐10.6) among contact‐traced flight‐only contacts sat within a two‐seat radius. The AR among 92 co‐travellers with known non‐flight exposure to infectious cases was 13.0% (95%CI 7.6%‐21.4%). There were insufficient numbers to assess differences between subgroups.ConclusionWe conclude that risk of symptomatic COVID‐19 due to transmission on short to medium‐haul flights is low, and recommend prioritising contact‐tracing of close contacts and co‐travellers where resources are limited. Further research on risk on aircraft is encouraged.     

Increased risk of rhinovirus infection in children during the coronavirus disease‐19 pandemic

BackgroundCoronavirus disease (COVID‐19), which is caused by severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2), was first detected in Japan in January 2020 and has spread throughout the country. Previous studies have reported that viral interference among influenza virus, rhinovirus, and other respiratory viruses can affect viral infections at the host and population level.MethodsTo investigate the impact of COVID‐19 on influenza and other respiratory virus infections, we analyzed clinical specimens collected from 2244 patients in Japan with respiratory diseases between January 2018 and September 2020.ResultsThe frequency of influenza and other respiratory viruses (coxsackievirus A and B; echovirus; enterovirus; human coronavirus 229E, HKU1, NL63, and OC43; human metapneumovirus; human parainfluenza virus 1, 2, 3, and 4; human parechovirus; human respiratory syncytial virus; human adenovirus; human bocavirus; human parvovirus B19; herpes simplex virus type 1; and varicella‐zoster virus) was appreciably reduced among all patients during the COVID‐19 pandemic except for that of rhinovirus in children younger than 10 years, which was appreciably increased. COVID‐19 has not spread among this age group, suggesting an increased risk of rhinovirus infection in children.ConclusionsRhinovirus infections should be continuously monitored to understand their increased risk during the COVID‐19 pandemic and viral interference with SARS‐CoV‐2.     

COVID‐19 vaccine effectiveness against hospitalization due to SARS‐CoV‐2: A test‐negative design study based on Severe Acute Respiratory Infection (SARI) sentinel surveillance in Spain

BackgroundWith the emergence of SARS‐CoV‐2, influenza surveillance systems in Spain were transformed into a new syndromic sentinel surveillance system. The Acute Respiratory Infection Surveillance System (SiVIRA in Spanish) is based on a sentinel network for acute respiratory infection (ARI) surveillance in primary care and a network of sentinel hospitals for severe ARI (SARI) surveillance in hospitals.MethodsUsing a test‐negative design and data from SARI admissions notified to SiVIRA between January 1 and October 3, 2021, we estimated COVID‐19 vaccine effectiveness (VE) against hospitalization, by age group, vaccine type, time since vaccination, and SARS‐CoV‐2 variant.ResultsVE was 89% (95% CI: 83–93) against COVID‐19 hospitalization overall in persons aged 20 years and older. VE was higher for mRNA vaccines, and lower for those aged 80 years and older, with a decrease in protection beyond 3 months of completing vaccination, and a further decrease after 5 months. We found no differences between periods with circulation of Alpha or Delta SARS‐CoV‐2 variants, although variant‐specific VE was slightly higher against Alpha.ConclusionsThe SiVIRA sentinel hospital surveillance network in Spain was able to describe clinical and epidemiological characteristics of SARI hospitalizations and provide estimates of COVID‐19 VE in the population under surveillance. Our estimates add to evidence of high effectiveness of mRNA vaccines against severe COVID‐19 and waning of protection with time since vaccination in those aged 80 or older. No substantial differences were observed between SARS‐CoV‐2 variants (Alpha vs. Delta).     

BNT162b2 vaccination reduced infections and transmission in a COVID‐19 outbreak in a nursing home in Germany, 2021

BackgroundA SARS‐CoV‐2 outbreak was detected in a nursing home in February 2021 after residents and staff had received two doses of BNT162b2 vaccine in January 2021.MethodsNursing home staff, long‐term residents and day‐care receivers were included in a retrospective cohort study. We calculated attack rates (AR), secondary AR (SAR) and their 95% binomial confidence interval (CI), and we compared them using Fisher''s exact test or chi‐squared test, depending on the sample size. We used Poisson regression with robust error estimates to calculate vaccine effectiveness against SARS‐COV‐2 infections. We selected variables based on directed acyclic graphs. As a proxy for viral load at diagnosis, we compared the mean Ct values at diagnosis using t tests or Mann–Whitney U tests.ResultsThe adjusted vaccine effectiveness against infection was 56% (95% CI: 15–77%, p = 0.04). Ct values at diagnosis were higher when intervals after receiving the second vaccination were longer (>21 vs. ≤21 days: 4.48 cycles, p = 0.08). The SAR was 67% lower in households of vaccinated (2/9 [22.2%]) than of unvaccinated infected staff (12/18 [66.7%]; p = 0.046). Vaccination rates were lowest among staff with close physical contact to care‐receivers (46%). The highest AR in vaccinated staff had those working on wards (14%).ConclusionsVaccination reduced the risk for SARS‐CoV‐2 infection, viral load and transmission; however, non‐pharmaceutical interventions remain essential to reduce transmission of SARS‐CoV‐2 infections, even for vaccinated individuals. Vaccination coverage of staff ought to increase reduction of infections among themselves, their household members and residents.     

Effectiveness of two and three mRNA COVID‐19 vaccine doses against Omicron‐ and Delta‐Related outpatient illness among adults,October 2021–February 2022

BackgroundWe estimated SARS‐CoV‐2 Delta‐ and Omicron‐specific effectiveness of two and three mRNA COVID‐19 vaccine doses in adults against symptomatic illness in US outpatient settings.MethodsBetween October 1, 2021, and February 12, 2022, research staff consented and enrolled eligible participants who had fever, cough, or loss of taste or smell and sought outpatient medical care or clinical SARS‐CoV‐2 testing within 10 days of illness onset. Using the test‐negative design, we compared the odds of receiving two or three mRNA COVID‐19 vaccine doses among SARS‐CoV‐2 cases versus controls using logistic regression. Regression models were adjusted for study site, age, onset week, and prior SARS‐CoV‐2 infection. Vaccine effectiveness (VE) was calculated as (1 − adjusted odds ratio) × 100%.ResultsAmong 3847 participants included for analysis, 574 (32%) of 1775 tested positive for SARS‐CoV‐2 during the Delta predominant period and 1006 (56%) of 1794 participants tested positive during the Omicron predominant period. When Delta predominated, VE against symptomatic illness in outpatient settings was 63% (95% CI: 51% to 72%) among mRNA two‐dose recipients and 96% (95% CI: 93% to 98%) for three‐dose recipients. When Omicron predominated, VE was 21% (95% CI: −6% to 41%) among two‐dose recipients and 62% (95% CI: 48% to 72%) among three‐dose recipients.ConclusionsIn this adult population, three mRNA COVID‐19 vaccine doses provided substantial protection against symptomatic illness in outpatient settings when the Omicron variant became the predominant cause of COVID‐19 in the United States. These findings support the recommendation for a third mRNA COVID‐19 vaccine dose.     

Trends in seroprevalence of SARS‐CoV‐2 and infection fatality rate in the Norwegian population through the first year of the COVID‐19 pandemic

BackgroundInfection with the novel coronavirus SARS‐CoV‐2 induces antibodies that can be used as a proxy for COVID‐19. We present a repeated nationwide cross‐sectional study assessing the seroprevalence of SARS‐CoV‐2, the infection fatality rate (IFR), and infection hospitalization rate (IHR) during the first year of the pandemic in Norway.MethodsResidual serum samples were solicited in April/May 2020 (Round 1), in July/August 2020 (Round 2) and in January 2021 (Round 3). Antibodies against SARS‐CoV‐2 were measured using a flow cytometer‐based assay. Aggregate data on confirmed cases, COVID‐19‐associated deaths and hospitalizations were obtained from the Emergency preparedness registry for COVID‐19 (Beredt C19), and the seroprevalence estimates were used to estimate IFR and IHR.ResultsAntibodies against SARS‐CoV‐2 were measured in 4840 samples. The estimated seroprevalence increased from 0.8% (95% credible interval [CrI] 0.4%–1.3%) after the first wave of the pandemic (Rounds 1 and 2 combined) to 3.2% (95% CrI 2.3%–4.2%) (Round 3). The IFR and IHR were higher in the first wave than in the second wave and increased with age. The IFR was 0.2% (95% CrI 0.1%–0.3%), and IHR was 0.9% (95% CrI 0.6%–1.5%) for the second wave.ConclusionsThe seroprevalence estimates show a cumulative increase of SARS‐CoV‐2 infections over time in the Norwegian population and suggest some under‐recording of confirmed cases. The IFR and IHR were low, corresponding to the relatively low number of COVID‐19‐associated deaths and hospitalizations in Norway. Most of the Norwegian population was still susceptible to SARS‐CoV‐2 infection after the first year of the pandemic.     

Prevalence of antibodies against SARS‐CoV‐2 in the Norwegian population,August 2021

BackgroundOne year into the COVID‐19 pandemic, the cumulative number of confirmed COVID‐19 cases in Norway was still low. In January 2021, when the Norwegian COVID‐19 vaccination campaign started, the national seroprevalence estimate of SARS‐CoV‐2 antibodies was 3.2%. We have conducted a nationwide cross‐sectional study in August 2021 to investigate the overall prevalence of SARS‐CoV‐2 antibodies in Norway after 8 months of COVID‐19 mass vaccination and a third wave of SARS‐CoV‐2 infection.MethodsResidual sera were collected from laboratories across Norway in August 2021. In IgG antibodies against the spike protein, the spike receptor binding domain (RBD) and the nucleocapsid protein of SARS‐CoV‐2 were measured by a bead‐based flow cytometric assay.ResultsIn total, 1926 residual sera were collected from individuals aged 0–98 years; 55.1% were from women. The overall national estimated seroprevalence from vaccination and/or infection was 62.6% (credible interval [CrI] 60.1%–65.2%) based on having antibodies against both spike and RBD. Estimated seroprevalence increased with age. Among all samples, 11.7% had antibodies against nucleocapsid. For unvaccinated children <12 years, the seroprevalence estimate due to SARS‐CoV‐2 infection was 12.5% (95% CrI 9.3%–16.1%). Of seropositive samples from the unvaccinated children, 31.9% lacked anti‐nucleocapsid antibodies.ConclusionsThe high overall SARS‐CoV‐2 seroprevalence estimates are in line with Norwegian registry data. Vaccination, not infection, contributed the most to the high seroprevalence in August 2021. Lack of antibodies against nucleocapsid should not automatically be interpreted as absence of previous infection as this could lead to underestimation of COVID‐19 cases in seroprevalence studies.