Estimated number of lives directly saved by COVID-19 vaccination programs in the WHO European Region, December 2020 to March 2023 (preprint)

BackgroundBy March 2023, 54 countries, areas and territories (thereafter "CAT") reported over 2.2 million coronavirus disease 2019 (COVID-19) deaths to the World Health Organization (WHO) Regional Office for Europe (1). Here, we estimate how many lives were directly saved by vaccinating adults in the Region, from December 2020 through March 2023. MethodsWe estimated the number of lives directly saved by age-group, vaccine dose and circulating Variant of Concern (VOC) period, both regionally and nationally, using weekly data on COVID-19 mortality and COVID-19 vaccine uptake reported by 34 CAT, and vaccine effectiveness (VE) data from the literature. We calculated the percentage reduction in the number of expected and reported deaths. FindingsWe found that vaccines reduced deaths by 57% overall (CAT range: 15% to 75%), representing [~]1.4 million lives saved in those aged [≥]25 years (range: 0.7 million to 2.6 million): 96% of lives saved were aged [≥]60 years and 52% were aged [≥]80 years; first boosters saved 51%, and 67% were saved during the Omicron period. InterpretationOver nearly 2.5 years, most lives saved by COVID-19 vaccinationwere in older adults by first booster dose and during the Omicron period, reinforcing the importance of up-to-date vaccination among these most at-risk individuals. Further modelling work should evaluate indirect effects of vaccination and public health and social measures. FundingThis work was supported by a US Centers for Disease Control cooperative agreement (Grant number 6 NU511P000936-02-020), who had no role in data analysis or interpretation. DisclaimerThe authors affiliated with the World Health Organization (WHO) are alone responsible for the views expressed in this publication and they do not necessarily represent the decisions or policies of the WHO. Research in contextO_ST_ABSEvidence before this studyC_ST_ABSSince first identified in late 2019, COVID-19 has caused disproportionately high mortality rates in older adults. With the rapid development and licensing of novel COVID-19 vaccines, immunization campaigns across the WHO European Region started in late 2020 and early 2021, initially targeting the most vulnerable and exposed populations, including older adults, people with comorbidities and healthcare professionals. Several studies have estimated the number of lives saved by COVID-19 vaccination, both at national and multi-country level in the earlier stages of the pandemic. However, only one multi-country study has assessed the number of lives saved beyond the first year of the pandemic, particularly when the Omicron variant of concern (VOC) circulated, a period when vaccination coverage was high in many countries, areas and territories (CAT), but COVID-19 transmission was at its highest. Added value of this studyHere we quantified the impact of COVID-19 vaccination in adults by age-group, vaccine dose and period of circulation of VOC, across diverse settings, using real world data reported by 34 CAT in the WHO European Region for the period December 2020 to April 2023. We estimated that COVID-19 vaccination programs were associated with a 57% reduction (CAT range: 15% to 75%) in the number of deaths among the [≥]25 years old, representing over 1.5 million lives saved (range: 0.7 million to 2.6 million) in 34 European CAT during the first 2.5 years following vaccine introduction. The first booster savedthe most lives (721,122 / 1,408,967, (57%) of all lives saved). The [≥]60 years old age group accounted for 96% of the total lives saved (1,349,617 / 1,408,967) whereas the [≥]80 years old age group represented 52% of the total lives saved (728,858 / 1,408,967 lives saved) and 67% of all lives were saved during the Omicron period (942,571 / 1,408,967). Implications of all the available evidenceOur results reinforce the importance of up-to-date COVID-19 vaccination, particularly among older age-groups. Communication campaigns supporting COVID-19 vaccination should stress the value of COVID-19 vaccination in saving lives to ensure vulnerable groups are up-to-date with vaccination ahead of periods of potential increased transmission.

The respiratory syncytial virus surge in Austria, 2022, was caused by lineages present before the COVID-19 pandemic (preprint)

In 2022, Austria experienced a severe respiratory syncytial virus (RSV) epidemic with an earlier-than-usual start and increased numbers of paediatric patients in emergency departments. Nationwide multiyear genomic surveillance revealed that the surge was driven by RSV-B, however genotypes consisted of multiple lineages that were circulating prior to the pandemic.

Symptoms and risk factors for hospitalization of COVID-19 presented in primary care (preprint)

ObjectiveTo extend knowledge of early symptoms as a precondition of early identification, and to gain understanding of associations between early symptoms and the development of a severe course of the disease. DesignRetrospective observational study SettingAustrian GP practices in the year 2020, patients above 18 years were included. ParticipantsWe recruited 22 practices who included altogether 295 participants with a positive SARS-CoV-2 test. Main outcome measuresData collection comprised basic demographic data, risk factors and the recording of symptoms at several points in time in the course of the illness. Descriptive analyses for possible associations between demographics and symptoms were conducted by means of cross table. Group differences (hospitalized yes/no) were assessed using Fishers exact test. The significance level was set to 0.05; due to the observational character of the study, no adjustment for multiplicity was performed. ResultsLittle more than one third of patients report symptoms generally understood to be typical for Covid-19. Most patients present with a variety of unspecific complaints. We found symptoms indicating complicated disease, depending on when they appear. The number of symptoms is likely to be a predictor for the need of hospital care. More than 50% of patients still experience symptoms 14 days after onset. ConclusionsUnderrating unspecific symptoms as possible indicators for SARS-CoV-2 infection harbours the danger of overlooking early disease. Monitoring patients during their illness using the indicators for severe disease we identified may help to identify patients who are likely to profit from early intervention. Data availability statementAll data referred to in the manuscript are available from: Department of General Medicine and Family Practice, Karl Landsteiner Privatuniversitaet, Krems, Austria Article SummaryO_ST_ABSStrengths and limitationsC_ST_ABSO_LIThis study investigates data on the course of COVID-19 collected exclusively from patients in primary care and explores a wide range of symptoms. C_LIO_LIGPs were free to make their own testing decision according to their clinical judgement, and they followed each patient individually from day 1 to day 10 or 14. C_LIO_LILimitations of our study concern the limited number of patients, due to the increased workload under difficult working conditions during the pandemic as well as the effort not being remunerated. However, the number of cases needed to identify group differences was calculated in advance, and this number has been reached. Our overall results are in accordance with our preliminary result analyses. C_LI

Significant impact of nationwide SARS-CoV-2 lockdown measures on the circulation of other respiratory virus infections (preprint)

Since the worldwide spread of SARS-CoV-2, different European countries reacted with temporarily nationwide lockdowns with the aim to limit the virus transmission in the population. Also Austria started a lockdown of public life in March. In this study we investigated whether the circulation of different respiratory virus infections in Austria, as assessed by using the established respiratory virus surveillance system, is affected by these measures as well and may reflect the success of the lockdown in limiting respiratory virus transmission. Sentinel data obtained for influenza virus, respiratory syncytial virus, human metapneumovirus and rhinovirus cases were analyzed and compared between the season 2019/ 2020 and the five previous seasons. We observed a rapid and statistically significant reduction of cumulative cases for all these viruses within short time after the lockdown in March 2020, compared to previous seasons (each p<0.001). Also, sentinel screening for SARS-CoV-2 infections was performed and a decrease of SARS-CoV-2 was seen after the lockdown. While for the seasonally occurring viruses as influenza, respiratory syncytial virus or human metapneumovirus the lockdown led to the end of the annual epidemics, a re-increase of rhinovirus infections was observed after liberalization of numerous lockdown measures.  Our data provide evidence that occurrence of different respiratory virus infections reflect not only the efficiency of lockdown measures taken against SARS-CoV-2 but also the effects of their release on respiratory transmission.

Mutational dynamics and transmission properties of SARS-CoV-2 superspreading events in Austria (preprint)

Superspreading events shape the COVID-19 pandemic. Here we provide a national-scale analysis of SARS-CoV-2 outbreaks in Austria, a country that played a major role for virus transmission across Europe and beyond. Capitalizing on a national epidemiological surveillance system, we performed deep whole-genome sequencing of virus isolates from 576 samples to cover major Austrian SARS-CoV-2 clusters. Our data chart a map of early viral spreading in Europe, including the path from low-frequency mutations to fixation. Detailed epidemiological surveys enabled us to calculate the effective SARS-CoV-2 population bottlenecks during transmission and unveil time-resolved intra-patient viral quasispecies dynamics. This study demonstrates the power of integrating deep viral genome sequencing and epidemiological data to better understand how SARS-CoV-2 spreads through populations. Graphical Abstract O_FIG_DISPLAY_L [Figure 1] M_FIG_DISPLAY C_FIG_DISPLAY

RT-PCR testing to detect a COVID-19 outbreak in Austria: rapid, accurate and early diagnosis in primary care (The REAP study) (preprint)

Background Delay in COVID-19 detection has led to a major pandemic. We report rapid early detection of SARS-CoV-2 by reverse transcriptase-polymerase chain reaction (RT-PCR), comparing it to the serostatus of convalescent infection, at an Austrian National Sentinel Surveillance Practice in an isolated ski-resort serving a population of 22,829 people. Methods Retrospective dataset of all 73 patients presenting with mild to moderate flu-like symptoms to a sentinel practice in the ski-resort of Schladming-Dachstein, Austria, between 24 February and 03 April, 2020. We split the outbreak in two halves, by dividing the period from the first to the last case by two, to characterise the following three cohorts of patients with confirmed infection: people with reactive RT-PCR presenting during the first half (early acute infection) vs. those presenting in the second half (late acute), and people with non-reactive RT-PCR (late convalescent). For each cohort we report the number of cases detected, the accuracy of RT-PCR and the duration of symptoms. We also report multivariate regression of 15 clinical symptoms as covariates, comparing all people with convalescent infection to those with acute infection. Findings All 73 patients had SARS-CoV-2 RT-PCR testing. 22 patients were diagnosed with COVID-19, comprising: 8 patients presenting early acute, and 7 presenting late acute and 7 late convalescent respectively; 44 patients tested SARS-COV-2 negative, and 7 were excluded. RT-PCR sensitivity was high (100%) among acute presenters, but dropped to 50% in the second half of the outbreak; specificity was 100%. The mean duration of symptoms was 2 days (range 1-4) among early acute presenters, and 4.4 days (1-7) among late acute and 8 days (2-12) among late convalescent presenters respectively. Convalescent infection was only associated with loss of taste (ORs=6.02;p=0.047). Acute infection was associated with loss of taste (OR=571.72;p=0.029), nausea and vomiting (OR=370.11;p=0.018), breathlessness (OR=134.46;p=0.049), and myalgia (OR=121.82;p=0.032); but not loss of smell, fever or cough. Interpretation RT-PCR rapidly and reliably detects early COVID-19 among people presenting with viral illness and multiple symptoms in primary care, particularly during the early phase of an outbreak. RT-PCR testing in primary care should be prioritised for effective COVID-19 prevention and control.