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Summary BackgroundBivalent mRNA-based COVID-19 vaccines encoding the ancestral and Omicron spike protein were developed as a countermeasure against antigenically distinct SARS-CoV-2 variants. We compared the (variant-specific) immunogenicity and reactogenicity of mRNA-based bivalent Omicron BA.1 vaccines in individuals who were primed with adenovirus- or mRNA-based vaccines. MethodsIn this open-label, multicenter, randomized, controlled trial, healthcare workers primed with Ad26.COV2.S or mRNA-based vaccines were boosted with mRNA-1273.214 or BNT162b2 OMI BA.1. The primary endpoint was the fold change in S1-specific IgG antibodies pre- and 28 days after booster vaccination. Secondary outcomes were fast response, (antibody levels on day 7), reactogenicity, neutralization of circulating variants and (cross-reactive) SARS-CoV-2-specific T-cell responses. FindingsNo effect of different priming regimens was observed on bivalent vaccination boosted S1-specific IgG antibodies. The largest increase in S1-specific IgG antibodies occurred between day 0 and 7 after bivalent booster. Neutralizing antibodies targeting the variants in the bivalent vaccine (ancestral SARS-CoV-2 and Omicron BA.1) were boosted. In addition, neutralizing antibodies against the circulating Omicron BA.5 variant increased after BA.1 bivalent booster. T-cell responses were boosted and retained reactivity with variants from the Omicron sub-lineage. InterpretationBivalent booster vaccination with mRNA-1273.214 or BNT162b2 OMI BA.1 resulted in a rapid recall of humoral and cellular immune responses independent of the initial priming regimen. Although no preferential boosting of variant-specific responses was observed, the induced antibodies and T-cells cross-reacted with Omicron BA.1 and BA.5. It remains crucial to monitor immunity at the population level, and simultaneously antigenic drift at the virus level, to determine the necessity (and timing) of COVID-19 booster vaccinations. FundingThe Netherlands Organization for Health Research and Development (ZonMw) grant agreement 10430072110001. Research in contextO_ST_ABSEvidence before this studyC_ST_ABSVaccination against coronavirus disease-2019 (COVID-19) initially provided high levels of protection from both infection and severe disease. However, the emergence of antigenically distinct variants resulted in frequent breakthrough infections, especially with the emergence of variants from the Omicron sub-lineages. The frequent mutations in the Spike protein, and specifically the receptor binding domain (RBD), resulted in the recommendation by the WHO advisory group to update vaccines with novel antigens. Bivalent mRNA-based vaccines, encoding the Spike protein from both the ancestral SARS-CoV-2 and Omicron BA.1 (and later on BA.5) were subsequently introduced. Initial small comparative studies have been released on the evaluation of these bivalent vaccines, but it is essential is to evaluate the immunogenicity and reactogenicity of the vaccines against the background of different priming regimens. Added value of this studyThe SWITCH ON trial evaluated the bivalent booster vaccines BNT162b2 OMI BA.1 and mRNA-1273.214 vaccine in a cohort of Dutch healthcare workers. Study participants were primed with either Ad26.COV2.S, mRNA-1273, or BNT162b2. The study investigated three important topics: (1) immunogenicity of Omicron BA.1 bivalent vaccines after Ad26.COV2.S- or mRNA-based vaccine priming, (2) rapid immunological recall responses, indicative of preserved humoral and cellular immunological memory, and (3) cross-reactivity with relevant variants after booster vaccination. Implication of all the available evidenceVaccination with the bivalent booster mRNA-1273.214 or BNT162b2 OMI BA.1 resulted in a rapid recall of humoral and cellular immune responses independent of the initial priming regimen. The largest fraction of (neutralizing) antibodies and virus-specific T-cells was recalled within 7 days post booster vaccination. Although no preferential boosting of variant-specific responses was observed, the induced antibodies and T-cells cross-reacted with Omicron BA.1, which was included in the vaccine, but also the more antigenically distinct BA.5. It remains crucial to monitor immunity at the population level, and simultaneously antigenic drift at the virus level, to determine the necessity (and timing) of COVID-19 booster vaccinations.
ABSTRACT
A large proportion of the global population received a single dose of the Ad26.COV2.S coronavirus disease-2019 (COVID-19) vaccine as priming vaccination, which was shown to provide protection against moderate to severe COVID-19. However, the emergence of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) variants that harbor immune-evasive mutations in the spike protein led to the recommendation of booster vaccinations after Ad26.COV2.S priming. Recent studies showed that heterologous booster vaccination with an mRNA-based vaccine following Ad26.COV2.S priming leads to high antibody levels. However, how heterologous booster vaccination affects other functional aspects of the immune response remains unknown. Here, we performed immunological profiling on samples obtained from Ad26.COV2.S-vaccinated individuals before and after a homologous (Ad26.COV2.S) or heterologous (mRNA-1273 or BNT162b2) booster vaccination. Both homologous and heterologous booster vaccination increased antibodies with multiple functionalities towards ancestral SARS-CoV-2, the Delta and Omicron BA.1 variants. Especially, mRNA-based booster vaccination induced high levels of neutralizing antibodies and antibodies with various Fc-mediated effector functions such as antibody-dependent cellular cytotoxicity and phagocytosis. In contrast, T cell responses were similar in magnitude following homologous or heterologous booster vaccination, and retained functionality towards Delta and Omicron BA.1. However, only heterologous booster vaccination with an mRNA-based vaccine led to the expansion of SARS-CoV-2-specific T cell clones, without an increase in the breadth of the T cell repertoire as assessed by T cell receptor sequencing. In conclusion, we show that Ad26.COV2.S priming vaccination provides a solid immunological base for heterologous boosting with an mRNA-based COVID-19 vaccine, increasing humoral and cellular responses targeting newly emerging variants of concern. One sentence summaryAd26.COV2.S priming provides a solid immunological base for extension of cellular and humoral immune responses following an mRNA-based booster.
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The Omicron BA.1 (B.1.1.529) SARS-CoV-2 variant is characterized by a high number of mutations in the viral genome, associated with immune-escape and increased viral spread. It remains unclear whether milder COVID-19 disease progression observed after infection with Omicron BA.1 in humans is due to reduced pathogenicity of the virus or due to pre-existing immunity from vaccination or previous infection. Here, we inoculated hamsters with Omicron BA.1 to evaluate pathogenicity and kinetics of viral shedding, compared to Delta (B.1.617.2) and to animals re-challenged with Omicron BA.1 after previous SARS-CoV-2 614G infection. Omicron BA.1 infected animals showed reduced clinical signs, pathological changes, and viral shedding, compared to Delta-infected animals, but still showed gross- and histopathological evidence of pneumonia. Pre-existing immunity reduced viral shedding and protected against pneumonia. Our data indicate that the observed decrease of disease severity is in part due to intrinsic properties of the Omicron BA.1 variant.
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The emergence and rapid spread of SARS-CoV-2 variants may impact vaccine efficacy significantly1. The Omicron variant termed BA.2, which differs genetically substantially from BA.1, is currently replacing BA.1 in several countries, but its antigenic characteristics have not yet been assessed2,3. Here, we used antigenic cartography to quantify and visualize antigenic differences between SARS-CoV-2 variants using hamster sera obtained after primary infection. Whereas early variants are antigenically similar, clustering relatively close to each other in antigenic space, Omicron BA.1 and BA.2 have evolved as two distinct antigenic outliers. Our data show that BA.1 and BA.2 both escape (vaccine-induced) antibody responses as a result of different antigenic characteristics. Close monitoring of the antigenic changes of SARS-CoV-2 using antigenic cartography can be helpful in the selection of future vaccine strains.
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BackgroundConvalescent plasma (CP) for hospitalized patients with COVID-19 has not demonstrated clear benefits. However, data on outpatients with early symptoms are scarce. We aimed to assess whether treatment with CP administered during the first 7 days of symptoms reduced the disease progression or risk of hospitalization of outpatients. MethodsTwo double-blind randomized trials (NCT04621123, NCT04589949) were merged with data pooling starting when <20% of their predefined sample size had been recruited. A Bayesian adaptive individual patient data meta-analysis was implemented. Analyses were done with Bayesian proportional odds and logistic models, where odds ratios (OR)<1.0 indicate a favorable outcome for CP. Fourteen study sites across the Netherlands and Catalonia in Spain participated in the trial. The two studies included outpatients aged [≥]50 years and diagnosed with COVID-19 and symptomatic for [≤]7days. The intervention consisted of one unit (200-300mL) of CP with a predefined minimum level of antibodies. The two primary endpoints were (a) a 5-point disease severity scale (fully recovered by day 7 or not, hospital or ICU admission and death) and (b) a composite of hospitalization or death. ResultsOf 797 patients included, 390 received CP and 392 placebo. At baseline, they had a median age of 58 years, 1 comorbidity, symptoms for 5 days and 93% tested negative for SARS-CoV-2 S-protein IgG antibodies. Seventy-four patients were hospitalized, 6 required mechanical ventilation and 3 died. The OR of CP for an improved disease severity scale was 0.936 (credible interval (CI) 0.667-1.311). The OR for hospitalization or death was 0.919 (CI 0.592-1.416). The effect of CP on hospital admission or death was largest in patients with [≤]5 days of symptoms (OR 0.658, 95% CI 0.394-1.085). CP did not decrease the time to full symptom resolution (p=0.62). ConclusionTreatment with CP of outpatients in the first 7 days of symptoms did not improve the outcome of COVID-19. The possible beneficial effect in patients with [≤]5 days of symptoms requires further study. RegistrationNCT04621123 and NCT04589949 on https://www.clinicaltrials.gov Funding sourceZONMW, the Netherlands, grant number 10430062010001. SUPPORT-E, grant number 101015756 YoMeCorono, www.tomecorono.com The Fight AIDS and Infectious Diseases Foundation with funding from the pharmaceutical company Grifols S.A
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BackgroundIn face of the developing COVID-19 pandemic with a need for rapid and practical vaccination strategies, Ad26.COV2.S was approved as single shot immunization regimen. While effective against severe COVID-19, Ad26.COV2.S vaccination induces lower SARS-CoV-2-specific antibody levels compared to its mRNA-based counterparts. To support decision making on the need for booster vaccinations in Ad26.COV2.S-primed individuals, we assessed the immunogenicity and reactogenicity of homologous and heterologous booster vaccinations in Ad26.COV2.S-primed health care workers (HCWs). MethodsThe SWITCH trial is a single-(participant)-blinded, multi-center, randomized controlled trial among 434 HCWs who received a single Ad26.COV2.S vaccination. HCWs were randomized to no boost, Ad26.COV2.S boost, mRNA-1273 boost, or BNT162b2 boost. We assessed the level of SARS-CoV-2-specific binding antibodies, neutralizing antibodies against infectious virus, SARS-CoV-2-specific T-cell responses, and reactogenicity. ResultsHomologous and heterologous booster vaccinations resulted in an increase in SARS-CoV-2-specific binding antibodies, neutralizing antibodies and T-cell responses when compared to single Ad26.COV.2.S vaccination. In comparison with the homologous boost, the increase was significantly larger in heterologous regimens with the mRNA-based vaccines. mRNA-1273 boosting was most immunogenic, associated with higher reactogenicity. Only mild to moderate local and systemic reactions were observed on the first two days following booster. ConclusionsBoosting of Ad26.COV2.S-primed HCWs was well-tolerated and immunogenic. Strongest responses were detected after boosting with mRNA-based vaccines. Based on our data, efficacy on infection and transmission of boosters is expected. In addition to efficacy, decision making on boost vaccinations should include timing, target population, level of SARS CoV-2 circulation, and the global inequity in vaccine access. Trial registrationFunded by ZonMW (10430072110001); ClinicalTrials.gov number, NCT04927936.
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BackgroundSARS-CoV-2 vaccines are highly effective at preventing COVID-19-related morbidity and mortality. As no vaccine is 100% effective, breakthrough infections are expected to occur. MethodsWe analyzed the virological characteristics of 161 vaccine breakthrough infections in a population of 24,706 vaccinated healthcare workers (HCWs), using RT-PCR and virus culture. ResultsThe delta variant (B.1.617.2) was identified in the majority of cases. Despite similar Ct-values, we demonstrate lower probability of infectious virus detection in respiratory samples of vaccinated HCWs with breakthrough infections compared to unvaccinated HCWs with primary SARS-CoV-2 infections. Nevertheless, infectious virus was found in 68.6% of breakthrough infections and Ct-values decreased throughout the first 3 days of illness. ConclusionsWe conclude that rare vaccine breakthrough infections occur, but infectious virus shedding is reduced in these cases.
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Assays to measure SARS-CoV-2-specific neutralizing antibodies are important to monitor seroprevalence, to study asymptomatic infections and to reveal (intermediate) hosts. A recently developed assay, the surrogate virus-neutralization test (sVNT) is a quick and commercially available alternative to the "gold standard" virus neutralization assay using authentic virus, and does not require processing at BSL-3 level. The assay relies on the inhibition of binding of the receptor binding domain (RBD) on the spike (S) protein to human angiotensin-converting enzyme 2 (hACE2) by antibodies present in sera. As the sVNT does not require species- or isotype-specific conjugates, it can be similarly used for antibody detection in human and animal sera. In this study, we used 298 sera from PCR-confirmed COVID-19 patients and 151 sera from patients confirmed with other coronavirus or other (respiratory) infections, to evaluate the performance of the sVNT. To analyze the use of the assay in a One Health setting, we studied the presence of RBD-binding antibodies in 154 sera from nine animal species (cynomolgus and rhesus macaques, ferrets, rabbits, hamsters, cats, cattle, mink and dromedary camels). The sVNT showed a moderate to high sensitivity and a high specificity using sera from confirmed COVID-19 patients (91.3% and 100%, respectively) and animal sera (93.9% and 100%), however it lacked sensitivity to detect low titers. Significant correlations were found between the sVNT outcomes and PRNT50 and the Wantai total Ig and IgM ELISAs. While species-specific validation will be essential, our results show that the sVNT holds promise in detecting RBD-binding antibodies in multiple species.
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The mRNA-based BNT162b2 vaccine from Pfizer/BioNTech was the first registered COVID-19 vaccine and has been shown to be up to 95% effective in preventing SARS-CoV-2 infections. Little is known about the broad effects of the new class of mRNA vaccines, especially whether they have combined effects on innate and adaptive immune responses. Here we confirmed that BNT162b2 vaccination of healthy individuals induced effective humoral and cellular immunity against several SARS-CoV-2 variants. Interestingly, however, the BNT162b2 vaccine also modulated the production of inflammatory cytokines by innate immune cells upon stimulation with both specific (SARS-CoV-2) and non-specific (viral, fungal and bacterial) stimuli. The response of innate immune cells to TLR4 and TLR7/8 ligands was lower after BNT162b2 vaccination, while fungi-induced cytokine responses were stronger. In conclusion, the mRNA BNT162b2 vaccine induces complex functional reprogramming of innate immune responses, which should be considered in the development and use of this new class of vaccines.
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BackgroundPre-/asymptomatic close contacts of SARS-CoV-2 infected individuals were tested at day 5 after contact by real-time reverse transcriptase polymerase chain reaction (RT-PCR). Diagnostic accuracy of antigen-detecting rapid diagnostic tests (Ag-RDT) in pre-/asymptomatic close contacts was up till now unknown. MethodsWe performed a prospective cross-sectional diagnostic test accuracy study. Close contacts (e.g. selected via the test-and-trace program or contact tracing app) aged [≥]16 years and asymptomatic when requesting a test, were included consecutively and tested at day 5 at four Dutch public health service test sites. We evaluated two Ag-RDTs (BD Veritor System Ag-RDT (BD), and Roche/SD Biosensor Ag-RDT (SD-B)) with RT-PCR as the reference standard. Virus culture was performed in RT-PCR positive individuals to determine the viral load cut-off above which 95% was culture positive, as a proxy of infectiousness. ResultsOf 2,678 BD-tested individuals, 233 (8.7%) were RT-PCR positive and BD detected 149 (sensitivity 63.9%; 95% confidence interval 57.4%-70.1%). Out of 1,596 SD-B-tested individuals, 132 (8.3%) were RT-PCR positive and SD-B detected 83 (sensitivity 62.9%; 54.0%-71.1%). When applying an infectiousness viral load cut-off [≥] 5.2 log10 gene copies/mL, the sensitivity was 90.1% (84.2%-94.4%) for BD, 86.8% (78.1% to 93.0%) for SD-B overall, and 88.1% (80.5%-93.5%) for BD, 85.1% (74.3%-92.6%) for SD-B for those still asymptomatic at the actual time of sampling. Specificity was >99% for both Ag-RDTs in all analyses. ConclusionsThe sensitivity for detecting SARS-CoV-2 of both Ag-RDTs in pre-/asymptomatic close contacts is over 60%, increasing to over 85% after applying an infectiousness viral load cut-off. Trial registration numberNot applicable. A study protocol is available upon request.
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COVID-19 is associated to a wide range of extra-respiratory complications, of which the pathogenesis is currently not fully understood. In this study we report the temporal kinetics of viral RNA and inflammatory cytokines and chemokines in serum during the course of COVID-19. We show that a RNAemia occurs more frequently and lasts longer in patients that develop critical disease compared to patients that develop moderate or severe disease. Furthermore we show that concentrations of IL-10 and MCP-1--but not IL-6--are associated with viral load in serum. However, higher levels of IL-6 were associated with the development of critical disease. The direct association of inflammatory cytokines with viral load or disease severity highlights the complexity of systemic inflammatory response and the role of systemic viral spread.
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BackgroundRapid detection of infectious individuals is essential in stopping the further spread of SARS-CoV-2. Although rapid antigen test is not as sensitive as the gold standard RT-PCR, the time to result is decreased by day(s), strengthening the effectiveness of contact tracing. MethodsThe Roche/SD Biosensor lateral flow antigen rapid test was evaluated in a mild symptomatic population at a large drive through testing site. A second nasopharyngeal swab was directly tested with the rapid test on site and results were compared to RT-PCR and virus culture. Date of onset and symptoms were analysed using data from a clinical questionnaire. ResultsWe included 970 persons with complete data. Overall sensitivity and specificity were 84.9% (CI95% 79.1-89.4) and 99.5% (CI95% 98.7-99.8) which translated into a positive predictive value of 97.5% (CI95% 94.0-99.5) under the current regional PCR positivity of 19.2%. Sensitivity for people with high loads of viral RNA (ct <30, 2.17E+05 E gene copy/ml) and who presented within 7 days since symptom onset increased to 95.8% (CI95% 90.5-98.2). Band intensity and time to result correlated strongly with viral load thus strong positive bands could be read before the recommended time. Around 98% of all viable specimen with ct <30 were detected successfully indicating that the large majority of infectious people can be captured with this test. ConclusionAntigen rapid tests can detect mildly symptomatic cases in the early phase of disease thereby identifying the most infectious individuals. Using this assay can have a significant value in the speed and effectiveness of SARS-CoV-2 outbreak management. SummaryO_LIPeople with early onset and high viral load were detected with 98.2% sensitivity. C_LIO_LI97% of individuals in which virus could be cultured were detected by the rapid test. C_LIO_LIThis test is suitable to detect mild symptomatic cases. C_LI
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The zoonotic origin of the SARS-CoV-2 pandemic is still unknown. Animal experiments have shown that non-human primates, cats, ferrets, hamsters, rabbits and bats can be infected by SARS-CoV-2. In addition, SARS-CoV-2 RNA has been detected in felids, mink and dogs in the field. Here, we describe an in-depth investigation of outbreaks on 16 mink farms and humans living or working on these farms, using whole genome sequencing. We conclude that the virus was initially introduced from humans and has evolved, most likely reflecting widespread circulation among mink in the beginning of the infection period several weeks prior to detection. At the moment, despite enhanced biosecurity, early warning surveillance and immediate culling of infected farms, there is ongoing transmission between mink farms with three big transmission clusters with unknown modes of transmission. We also describe the first animal to human transmissions of SARS-CoV-2 in mink farms. One sentence summarySARS-CoV-2 transmission on mink farms.
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Effective clinical intervention strategies for COVID-19 are urgently needed. Although several clinical trials have evaluated the use of convalescent plasma containing virus-neutralizing antibodies, the effectiveness has not been proven. We show that hamsters treated with a high dose of human convalescent plasma or a monoclonal antibody were protected against weight loss showing reduced pneumonia and pulmonary virus replication compared to control animals. However, a ten-fold lower dose of convalescent plasma showed no protective effect. Thus, variable and relatively low levels of virus neutralizing antibodies in convalescent plasma may limit their use for effective antiviral therapy, favouring concentrated, purified (monoclonal) antibodies.
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Structured abstract for full paperO_ST_ABSBackgroundC_ST_ABSAfter recovery from COVID-19, most patients have anti-SARS-CoV-2 neutralizing antibodies. Their convalescent plasma could be an inexpensive and widely available treatment for COVID-19. MethodsThe Convalescent-plasma-for-COVID (ConCOVID) study was a randomized trial comparing convalescent plasma with standard of care therapy in patients hospitalized for COVID-19 in the Netherlands. Patients were randomized 1:1 and received 300ml of plasma with anti-SARS-CoV-2 neutralizing antibody titers of at least 1:80. The primary endpoint was day-60 mortality and key secondary endpoints were hospital stay and WHO 8-point disease severity scale improvement on day 15. ResultsThe trial was halted prematurely after 86 patients were enrolled. Although symptomatic for only 10 days (IQR 6-15) at the time of inclusion, 53 of 66 patients tested had anti-SARS-CoV-2 antibodies at baseline. A SARS-CoV-2 plaque reduction neutralization test showed neutralizing antibodies in 44 of the 56 (79%) patients tested with median titers comparable to the 115 donors (1:160 vs 1:160, p=0.40). These observations caused concerns about the potential benefit of convalescent plasma in the study population and after discussion with the data safety monitoring board, the study was discontinued. No difference in mortality (p=0.95), hospital stay (p=0.68) or day-15 disease severity (p=0.58) was observed between plasma treated patients and patients on standard of care. ConclusionMost COVID-19 patients already have high neutralizing antibody titers at hospital admission. Screening for antibodies and prioritizing convalescent plasma to risk groups with recent symptom onset will be key to identify patients that may benefit from convalescent plasma. Clinicaltrials.gov: NCT04342182
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BackgroundThe COVID-19 pandemic demands detailed understanding of the kinetics of antibody production induced by infection with SARS-CoV-2. We aimed to develop a high throughput multiplex assay to detect antibodies to SARS-CoV-2 to assess immunity to the virus in the general population. MethodsSpike protein subunits S1 and RBD, and Nucleoprotein were coupled to distinct microspheres. Sera collected before the emergence of SARS-CoV-2 (N=224), and of non-SARS-CoV-2 influenza-like illness (N=184), and laboratory-confirmed cases of SARS-CoV-2 infection (N=115) with various severity of COVID-19 were tested for SARS-CoV-2-specific concentrations of IgG. ResultsOur assay discriminated SARS-CoV-2-induced antibodies and those induced by other viruses. The assay obtained a specificity between 95.1 and 99.0% with a sensitivity ranging from 83.6-95.7%. By merging the test results for all 3 antigens a specificity of 100% was achieved with a sensitivity of at least 90%. Hospitalized COVID-19 patients developed higher IgG concentrations and the rate of IgG production increased faster compared to non-hospitalized cases. ConclusionsThe bead-based serological assay for quantitation of SARS-CoV-2-specific antibodies proved to be robust and can be conducted in many laboratories. Finally, we demonstrated that testing of antibodies against different antigens increases sensitivity and specificity compared to single antigen-specific IgG determination.
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BackgroundLong-term shedding of viral RNA in COVID-19 prevents timely discharge from the hospital or de-escalation of infection prevention and control practices. Key questions are the duration and determinants of infectious virus shedding. We assessed these questions using virus cultures of respiratory tract samples from hospitalized COVID-19 patients as a proxy for infectious virus shedding. MethodsClinical and virological data were obtained from 129 hospitalized COVID-19 patients (89 intensive care, 40 medium care). Generalized estimating equations were used to identify if viral RNA load, detection of viral subgenomic RNA, serum neutralizing antibody response, duration of symptoms, or immunocompromised status were predictive for a positive virus culture. FindingsInfectious virus shedding was detected in 23 of the 129 patients (17,8%). The median duration of shedding was 8 days post onset of symptoms (IQR 5 - 11) and the probability of detecting infectious virus dropped below 5% after 15,2 days post onset of symptoms (95% confidence interval (CI) 13,4 - 17,2). Multivariate analyses identified viral loads above 7 log10 RNA copies/mL (odds ratio [OR]; CI 14,7 (3,57-58,1; p<0,001) as independently associated with isolation of infectious SARS-CoV-2 from the respiratory tract. A serum neutralizing antibody titre of at least 1:20 (OR of 0,01 (CI 0,003-0,08; p<0,001) was independently associated with non-infectious SARS-CoV-2. InterpretationInfection prevention and control guidelines should take into account that patients with severe or critical COVID-19 may shed infectious virus for longer periods of time compared to what has been reported for in patients with mild COVID-19. Infectious virus shedding drops to undetectable levels below a viral RNA load threshold and once serum neutralizing antibodies are present, which warrants the use of quantitative viral RNA load assays and serological assays in test-based strategies to discontinue or de-escalate infection prevention and control precautions. Research in contextO_ST_ABSEvidence before this studyC_ST_ABSWe searched PubMed, bioRxiv, and medRxiv for articles that reported on shedding of infectious virus in COVID-19 patients using the search terms ("coronavirus" OR "SARS" OR "SARS-CoV-2" OR "COVID-19") AND ("shedding" OR "infectivity" OR "infectious" OR "virus culture") with no language or time restrictions. A detailed study on nine patients with mild COVID-19 reported that infectious virus could not be isolated after more than eight days of symptoms. The probability of isolating infectious virus was less than 5% when viral loads dropped below 6,51 Log10 RNA copies/mL. Similar results were obtained with a larger diagnostic sample set, but that study did not report on clinical parameters such as disease severity. Finally there is a report of a single patient shedding infectious virus up to 18 days after onset of symptoms. No published works were found on the shedding of infectious virus in patients with severe or critical COVID-19, and no published works were found on factors independently associated with shedding of infectious virus. Added value of this studyWe assessed the duration and determinants of infectious virus shedding in 129 patients with severe or critical COVID-19. The duration of infectious virus shedding ranged from 0 to 20 days post onset of symptoms (median 8 days, IQR 5 - 11). The probability of detecting infectious virus dropped below 5% after 15,2 days post onset of symptoms (95% confidence interval (CI) 13,4 - 17,2). Viral loads above 7 log10 RNA copies/mL were independently associated with detection of infectious SARS-CoV-2 from the respiratory tract (odds ratio [OR]; CI 14,7 (3,57-58,1; p<0,001). A serum neutralizing antibody titre of at least 1:20 (OR of 0,01 (CI 0,003-0,08; p<0,001) was independently associated with non-infectious SARS-CoV-2. Implications of all the available evidenceInfection prevention and control guidelines should take into account that patients with severe or critical COVID-19 may shed infectious virus for longer periods of time compared to what has been reported for in patients with mild COVID-19. Quantitative viral RNA load assays and serological assays should be used for test-based strategies to discontinue or de-escalate infection prevention and control precautions.
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SARS-CoV-2 is a novel coronavirus that has rapidly spread across the globe. In the Netherlands, the first case of SARS-CoV-2 has been notified on the 27th of February. Here, we describe the first three weeks of the SARS-CoV-2 outbreak in the Netherlands, which started with several different introductory events from Italy, Austria, Germany and France followed by local amplification in, and later also, outside the South of the Netherlands. The timely generation of whole genome sequences combined with epidemiological investigations facilitated early decision making in an attempt to control local transmission of SARS-CoV-2 in the Netherlands.
