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1.
Open forum infectious diseases ; 8(Suppl 1):S298-S299, 2021.
Article in English | EuropePMC | ID: covidwho-1602640

ABSTRACT

Background Background. Understanding the viral load and potential infectivity of individuals in nursing homes (NH) with repeat positive SARS-CoV-2 tests ≥ 90 days after initial infection has important implications for safety related to transmission in this high-risk setting. Methods Methods. We collected epidemiologic data by reviewing records of a convenience sample of NH residents and staff with respiratory specimens who had positive SARS-CoV-2 rRT-PCR test results from July 2020 through March 2021 and had a SARS-CoV-2 infection diagnosed ≥ 90 days prior. No fully vaccinated individuals were included. Each contributed one repeat positive specimen ≥ 90 days after initial, which was sent to CDC and retested using rRT-PCR. Specimens were assessed for replication-competent virus in cell culture if Cycle threshold (Ct) < 34 and sequenced if Ct < 30. Using Ct values as a proxy for viral RNA load, specimens were categorized as high (Ct < 30) or low (if Ct ≥ 30 or rRT-PCR negative at retesting). Continuous variables were compared using Wilcoxon signed-rank tests. Proportions were compared using Chi-squared or Fisher’s exact tests. Results Results. Of 64 unvaccinated individuals with specimens from 61 unique NHs, 14 (22%) were sent for culture and sequencing. Ten of 64 (16%) had a high viral RNA load, of which four (6%) were culture positive and none were known variants of interest or concern (Figure 1). Median days to repeat positive test result were 122 (Interquartile range (IQR): 103–229) and 201 (IQR: 139–254), respectively, for high versus low viral load specimens (p=0.13). More individuals with high viral loads (5/10, 50%) reported COVID-19 symptoms than with a low viral load (1/27, 4%, p=0.003). Most individuals (46/58, 79%) were tested following known or suspected exposures, with no significant differences between high and low viral load (p=0.18). Conclusion In this study, nearly 1 in 6 NH residents and staff with repeat positive tests after 90 days demonstrated high viral RNA loads and viable virus, indicating possible infectivity. While individuals with high RNA viral load may be more likely to be symptomatic, distinguishing asymptomatic individuals who have high viral loads may be difficult with timing since initial infection, other test results, or exposure history alone. Disclosures John A. Jernigan, MD, MS, Nothing to disclose.

2.
Clin Infect Dis ; 2021 Feb 18.
Article in English | MEDLINE | ID: covidwho-1595231

ABSTRACT

BACKGROUND: We investigated patients with potential SARS-CoV-2 reinfection in the United States during May-July 2020. METHODS: We conducted case finding for patients with potential SARS-CoV-2 reinfection through the Emerging Infections Network. Cases reported were screened for laboratory and clinical findings of potential reinfection followed by requests for medical records and laboratory specimens. Available medical records were abstracted to characterize patient demographics, comorbidities, clinical course, and laboratory test results. Submitted specimens underwent further testing, including RT-PCR, viral culture, whole genome sequencing, subgenomic RNA PCR, and testing for anti-SARS-CoV-2 total antibody. RESULTS: Among 73 potential reinfection patients with available records, 30 patients had recurrent COVID-19 symptoms explained by alternative diagnoses with concurrent SARS-CoV-2 positive RT-PCR, 24 patients remained asymptomatic after recovery but had recurrent or persistent RT-PCR, and 19 patients had recurrent COVID-19 symptoms with concurrent SARS-CoV-2 positive RT-PCR but no alternative diagnoses. These 19 patients had symptom recurrence a median of 57 days after initial symptom onset (interquartile range: 47 - 76). Six of these patients had paired specimens available for further testing, but none had laboratory findings confirming reinfections. Testing of an additional three patients with recurrent symptoms and alternative diagnoses also did not confirm reinfection. CONCLUSIONS: We did not confirm SARS-CoV-2 reinfection within 90 days of the initial infection based on the clinical and laboratory characteristics of cases in this investigation. Our findings support current CDC guidance around quarantine and testing for patients who have recovered from COVID-19.

5.
Open forum infectious diseases ; 8(Suppl 1):288-289, 2021.
Article in English | EuropePMC | ID: covidwho-1564846

ABSTRACT

Background In December 2020, B.1.1.7 lineage of SARS-CoV-2 was first detected in the United States and has since become the dominant lineage. Previous investigations involving B.1.1.7 suggested higher rates of transmission relative to non-B.1.1.7 lineages. We conducted a household transmission investigation to determine the secondary infection rates (SIR) of B.1.1.7 and non-B.1.1.7 SARS-CoV-2 lineages. Methods From January–April 2021, we enrolled members of households in San Diego County, CA, and Denver, CO metropolitan area (Tri-County), with a confirmed SARS-CoV-2 infection in a household member with illness onset date in the previous 10 days. CDC investigators visited households at enrollment and 14 days later at closeout to obtain demographic and clinical data and nasopharyngeal (NP) samples on all consenting household members. Interim visits, with collection of NP swabs, occurred if a participant became symptomatic during follow-up. NP samples were tested for SARS-CoV-2 using TaqPath™ RT-PCR test, where failure to amplify the spike protein results in S-Gene target failure (SGTF) may indicate B.1.1.7 lineage. Demographic characteristics and SIR were compared among SGTF and non-SGTF households using two-sided p-values with chi-square tests;95% confidence intervals (CI) were calculated with Wilson score intervals. Results 552 persons from 151 households were enrolled. 91 (60%) households were classified as SGTF, 57 (38%) non-SGTF, and 3 (2%) indeterminant. SGTF and non-SGTF households had similar sex distribution (49% female and 52% female, respectively;P=0.54) and age (median 30 years, interquartile range (IQR 14–47) and 31 years (IQR 15–45), respectively). Hispanic people accounted for 24% and 32% of enrolled members of SGTF and non-SGTF households, respectively (p=0.04). At least one secondary case occurred in 61% of SGTF and 58% of non-SGTF households (P=0.66). SIR was 52% (95%[CI] 46%-59%) for SGTF and 45% (95% CI 37%-53%) for non-SGTF households (P=0.18). Conclusion SIRs were high in both SGTF and non-SGTF households;our findings did not support an increase in SIR for SGTF relative to non-SGTF households in this setting. Sequence confirmed SARS-CoV-2 samples will provide further information on lineage specific SIRs. Disclosures All Authors: No reported disclosures

6.
Open forum infectious diseases ; 8(Suppl 1):114-115, 2021.
Article in English | EuropePMC | ID: covidwho-1564197

ABSTRACT

Background Human-to-feline and airborne transmission among cats of Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) has been described, though documented feline-to-human transmission has not been reported. In October 2020, all 3 Malayan tigers at a Tennessee AZA accredited zoo were diagnosed with symptomatic SARS-CoV-2 infection. We investigated to determine source and prevent further transmission. Methods Tiger nasal swab specimens were tested at the National Veterinary Services Laboratories (NVSL). An environmental assessment at the zoo was completed. We interviewed 18 staff who interacted with the tigers during the 2 weeks before animal symptom onset. Confirmed human cases were defined as persons testing positive for SARS-CoV-2 by RT-PCR during September 28–October 29, with tiger interaction during their 14-day incubation period. Interviewed staff had repeat SARS-CoV-2 RT-PCR and serum IgG testing on October 29. Tigers and staff testing positive had specimens sent to CDC for genomic sequencing. Tiger sequences were compared phylogenetically with 30 geographically associated human cases collected within 2 weeks of the outbreak and > 200 background sequences from TN. Results NVSL confirmed SARS-CoV-2 infection in all 3 tigers. Environmental assessment identified fencing between humans and animals allowing airflow and an open outdoor exhibit observation point above the habitat. Confirmed cases were identified in a tiger keeper and veterinary assistant;both developed symptoms after exposure to symptomatic tigers and one sample was genotyped. Staff did not report known contact with ill visitors. All staff were negative for SARS-CoV-2 IgG. The tigers and most temporally and geographically associated cases had genetic sequences in clade 20G and B.1.2. Tiger sequences were 3-6 single nucleotide polymorphisms different from the positive tiger keeper (Figure). Figure. Whole-genome phylogenetic analysis. Whole-genome phylogenetic analysis from a portion of clade 20G showing divergence estimates from SARS-CoV-2 Wuhan-Hu-1 reference genome with sequences from humans living in Tennessee and Malayan tigers sampled during the outbreak investigation in October 2020. Sequence analysis showed 3-6 single nucleotide polymorphisms (SNPs) differences between one human tiger keeper and all three tiger sequences. Differences are indicated by one-step edges (lines) between colored dots (individual SARS-CoV-2 sequenced infections). Numbers indicate unique sequences. Note not all analyzed sequences are shown in this figure. Conclusion Using a One Health approach, we concluded the index tiger was likely infected via transmission from an ill visitor at an exhibit observation point or unidentified asymptomatic staff. Infection spread to the other 2 tigers and tiger-to-human transmission to 2 staff is possible thereafter. The zoo was advised on infection control practices for humans and animals, and no additional cases were identified. Disclosures William Schaffner, MD, VBI Vaccines (Consultant)

7.
Preprint in English | Other preprints | ID: ppcovidwho-294830

ABSTRACT

Background Approximately 67% of U.S. households have pets. Limited data are available on SARS-CoV-2 in pets. We assessed SARS-CoV-2 infection in pet cohabitants as a sub-study of an ongoing COVID-19 household transmission investigation. Methods Mammalian pets from households with ≥1 person with laboratory-confirmed COVID-19 were eligible for inclusion from April–May 2020. Demographic/exposure information, oropharyngeal, nasal, rectal, and fur swabs, feces, and blood were collected from enrolled pets and tested by rRT-PCR and virus neutralization assays. Findings We enrolled 37 dogs and 19 cats from 34 of 41 eligible households. All oropharyngeal, nasal, and rectal swabs tested negative by rRT-PCR;one dog’s fur swabs (2%) tested positive by rRT-PCR at the first animal sampling. Among 47 pets with serological results from 30 households, eight (17%) pets (4 dogs, 4 cats) from 6 (20%) households had detectable SARS-CoV-2 neutralizing antibodies. In households with a seropositive pet, the proportion of people with laboratory-confirmed COVID-19 was greater (median 79%;range: 40–100%) compared to households with no seropositive pet (median 37%;range: 13–100%) (p=0.01). Thirty-three pets with serologic results had frequent daily contact (≥1 hour) with the human index patient before the person’s COVID-19 diagnosis. Of these 33 pets, 14 (42%) had decreased contact with the human index patient after diagnosis and none (0%) were seropositive;of the 19 (58%) pets with continued contact, 4 (21%) were seropositive. Interpretations Seropositive pets likely acquired infection from humans, which may occur more frequently than previously recognized. People with COVID-19 should restrict contact with animals. Funding Centers for Disease Control and Prevention, U.S. Department of Agriculture

8.
Preprint in English | EuropePMC | ID: ppcovidwho-293462

ABSTRACT

The divergence of SARS-CoV-2 into variants of concern/interest (VOC/VOI) necessitated analysis of their impact on vaccines. Escape from vaccine-induced antibodies by SARS-CoV-2 VOC/VOIs was analyzed to ascertain and rank their risk. The variants showed differential reductions in neutralization and replication titers by the post-vaccination sera with Beta variant showing the most neutralization escape that was mechanistically driven by mutations in both the N-terminal domain and receptor-binding domain of the spike.

9.
Emerg Infect Dis ; 27(12): 3052-3062, 2021 12.
Article in English | MEDLINE | ID: covidwho-1528794

ABSTRACT

Middle East respiratory syndrome coronavirus (MERS-CoV) infects humans and dromedary camels and is responsible for an ongoing outbreak of severe respiratory illness in humans in the Middle East. Although some mutations found in camel-derived MERS-CoV strains have been characterized, most natural variation found across MERS-CoV isolates remains unstudied. We report on the environmental stability, replication kinetics, and pathogenicity of several diverse isolates of MERS-CoV, as well as isolates of severe acute respiratory syndrome coronavirus 2, to serve as a basis of comparison with other stability studies. Although most MERS-CoV isolates had similar stability and pathogenicity in our experiments, the camel-derived isolate C/KSA/13 had reduced surface stability, and another camel isolate, C/BF/15, had reduced pathogenicity in a small animal model. These results suggest that although betacoronaviruses might have similar environmental stability profiles, individual variation can influence this phenotype, underscoring the need for continual global viral surveillance.


Subject(s)
COVID-19 , Middle East Respiratory Syndrome Coronavirus , Aerosols , Animals , Camelus , Humans , Middle East Respiratory Syndrome Coronavirus/genetics , SARS-CoV-2 , Virulence , Zoonoses
10.
MMWR Morb Mortal Wkly Rep ; 70(37): 1294-1299, 2021 Sep 17.
Article in English | MEDLINE | ID: covidwho-1417367

ABSTRACT

COVID-19 mRNA vaccines (Pfizer-BioNTech and Moderna) have been shown to be highly protective against COVID-19-associated hospitalizations (1-3). Data are limited on the level of protection against hospitalization among disproportionately affected populations in the United States, particularly during periods in which the B.1.617.2 (Delta) variant of SARS-CoV-2, the virus that causes COVID-19, predominates (2). U.S. veterans are older, more racially diverse, and have higher prevalences of underlying medical conditions than persons in the general U.S. population (2,4). CDC assessed the effectiveness of mRNA vaccines against COVID-19-associated hospitalization among 1,175 U.S. veterans aged ≥18 years hospitalized at five Veterans Affairs Medical Centers (VAMCs) during February 1-August 6, 2021. Among these hospitalized persons, 1,093 (93.0%) were men, the median age was 68 years, 574 (48.9%) were non-Hispanic Black (Black), 475 were non-Hispanic White (White), and 522 (44.4%) had a Charlson comorbidity index score of ≥3 (5). Overall adjusted vaccine effectiveness against COVID-19-associated hospitalization was 86.8% (95% confidence interval [CI] = 80.4%-91.1%) and was similar before (February 1-June 30) and during (July 1-August 6) SARS-CoV-2 Delta variant predominance (84.1% versus 89.3%, respectively). Vaccine effectiveness was 79.8% (95% CI = 67.7%-87.4%) among adults aged ≥65 years and 95.1% (95% CI = 89.1%-97.8%) among those aged 18-64 years. COVID-19 mRNA vaccines are highly effective in preventing COVID-19-associated hospitalization in this older, racially diverse population of predominately male U.S. veterans. Additional evaluations of vaccine effectiveness among various age groups are warranted. To prevent COVID-19-related hospitalizations, all eligible persons should receive COVID-19 vaccination.


Subject(s)
COVID-19 Vaccines/administration & dosage , COVID-19/prevention & control , Hospitalization/statistics & numerical data , Veterans/statistics & numerical data , Adolescent , Adult , Aged , COVID-19/epidemiology , COVID-19/therapy , Female , Hospitals, Veterans , Humans , Male , Middle Aged , United States/epidemiology , United States Department of Veterans Affairs , Vaccines, Synthetic , Young Adult
11.
Viruses ; 13(9)2021 09 12.
Article in English | MEDLINE | ID: covidwho-1411082

ABSTRACT

Approximately 67% of U.S. households have pets. Limited data are available on SARS-CoV-2 in pets. We assessed SARS-CoV-2 infection in pets during a COVID-19 household transmission investigation. Pets from households with ≥1 person with laboratory-confirmed COVID-19 were eligible for inclusion from April-May 2020. We enrolled 37 dogs and 19 cats from 34 households. All oropharyngeal, nasal, and rectal swabs tested negative by rRT-PCR; one dog's fur swabs (2%) tested positive by rRT-PCR at the first sampling. Among 47 pets with serological results, eight (17%) pets (four dogs, four cats) from 6/30 (20%) households had detectable SARS-CoV-2 neutralizing antibodies. In households with a seropositive pet, the proportion of people with laboratory-confirmed COVID-19 was greater (median 79%; range: 40-100%) compared to households with no seropositive pet (median 37%; range: 13-100%) (p = 0.01). Thirty-three pets with serologic results had frequent daily contact (≥1 h) with the index patient before the person's COVID-19 diagnosis. Of these 33 pets, 14 (42%) had decreased contact with the index patient after diagnosis and none were seropositive; of the 19 (58%) pets with continued contact, four (21%) were seropositive. Seropositive pets likely acquired infection after contact with people with COVID-19. People with COVID-19 should restrict contact with pets and other animals.


Subject(s)
COVID-19/epidemiology , COVID-19/virology , Pets/virology , SARS-CoV-2 , Animals , COVID-19/history , COVID-19/transmission , Cats , Dogs , Family Characteristics , History, 21st Century , Humans , Pets/history , Phylogeny , Population Surveillance , RNA, Viral , SARS-CoV-2/classification , SARS-CoV-2/genetics , SARS-CoV-2/isolation & purification , Seroepidemiologic Studies , Utah/epidemiology , Viral Zoonoses/epidemiology , Wisconsin/epidemiology
12.
MMWR Morb Mortal Wkly Rep ; 70(23): 846-850, 2021 Jun 11.
Article in English | MEDLINE | ID: covidwho-1389869

ABSTRACT

SARS-CoV-2, the virus that causes COVID-19, is constantly mutating, leading to new variants (1). Variants have the potential to affect transmission, disease severity, diagnostics, therapeutics, and natural and vaccine-induced immunity. In November 2020, CDC established national surveillance for SARS-CoV-2 variants using genomic sequencing. As of May 6, 2021, sequences from 177,044 SARS-CoV-2-positive specimens collected during December 20, 2020-May 6, 2021, from 55 U.S. jurisdictions had been generated by or reported to CDC. These included 3,275 sequences for the 2-week period ending January 2, 2021, compared with 25,000 sequences for the 2-week period ending April 24, 2021 (0.1% and 3.1% of reported positive SARS-CoV-2 tests, respectively). Because sequences might be generated by multiple laboratories and sequence availability varies both geographically and over time, CDC developed statistical weighting and variance estimation methods to generate population-based estimates of the proportions of identified variants among SARS-CoV-2 infections circulating nationwide and in each of the 10 U.S. Department of Health and Human Services (HHS) geographic regions.* During the 2-week period ending April 24, 2021, the B.1.1.7 and P.1 variants represented an estimated 66.0% and 5.0% of U.S. SARS-CoV-2 infections, respectively, demonstrating the rise to predominance of the B.1.1.7 variant of concern† (VOC) and emergence of the P.1 VOC in the United States. Using SARS-CoV-2 genomic surveillance methods to analyze surveillance data produces timely population-based estimates of the proportions of variants circulating nationally and regionally. Surveillance findings demonstrate the potential for new variants to emerge and become predominant, and the importance of robust genomic surveillance. Along with efforts to characterize the clinical and public health impact of SARS-CoV-2 variants, surveillance can help guide interventions to control the COVID-19 pandemic in the United States.


Subject(s)
COVID-19/virology , SARS-CoV-2/genetics , COVID-19/epidemiology , Epidemiological Monitoring , Humans , SARS-CoV-2/isolation & purification , United States/epidemiology
13.
MMWR Morb Mortal Wkly Rep ; 69(28): 918-922, 2020 Jul 17.
Article in English | MEDLINE | ID: covidwho-1389847

ABSTRACT

To limit introduction of SARS-CoV-2, the virus that causes coronavirus disease 2019 (COVID-19), the United States restricted travel from China on February 2, 2020, and from Europe on March 13. To determine whether local transmission of SARS-CoV-2 could be detected, the New York City (NYC) Department of Health and Mental Hygiene (DOHMH) conducted deidentified sentinel surveillance at six NYC hospital emergency departments (EDs) during March 1-20. On March 8, while testing availability for SARS-CoV-2 was still limited, DOHMH announced sustained community transmission of SARS-CoV-2 (1). At this time, twenty-six NYC residents had confirmed COVID-19, and ED visits for influenza-like illness* increased, despite decreased influenza virus circulation.† The following week, on March 15, when only seven of the 56 (13%) patients with known exposure histories had exposure outside of NYC, the level of community SARS-CoV-2 transmission status was elevated from sustained community transmission to widespread community transmission (2). Through sentinel surveillance during March 1-20, DOHMH collected 544 specimens from patients with influenza-like symptoms (ILS)§ who had negative test results for influenza and, in some instances, other respiratory pathogens.¶ All 544 specimens were tested for SARS-CoV-2 at CDC; 36 (6.6%) tested positive. Using genetic sequencing, CDC determined that the sequences of most SARS-CoV-2-positive specimens resembled those circulating in Europe, suggesting probable introductions of SARS-CoV-2 from Europe, from other U.S. locations, and local introductions from within New York. These findings demonstrate that partnering with health care facilities and developing the systems needed for rapid implementation of sentinel surveillance, coupled with capacity for genetic sequencing before an outbreak, can help inform timely containment and mitigation strategies.


Subject(s)
Betacoronavirus/genetics , Betacoronavirus/isolation & purification , Community-Acquired Infections/diagnosis , Community-Acquired Infections/virology , Coronavirus Infections/diagnosis , Coronavirus Infections/virology , Pneumonia, Viral/diagnosis , Pneumonia, Viral/virology , Sentinel Surveillance , Adolescent , Adult , Aged , COVID-19 , Child , Child, Preschool , Community-Acquired Infections/epidemiology , Coronavirus Infections/epidemiology , Emergency Service, Hospital , Female , Humans , Infant , Male , Middle Aged , New York City/epidemiology , Pandemics , Pneumonia, Viral/epidemiology , SARS-CoV-2 , Sequence Analysis , Travel-Related Illness , Young Adult
14.
Morbidity and Mortality Weekly Report ; 70(3):95-99, 2021.
Article in English | GIM | ID: covidwho-1374676

ABSTRACT

This report focuses on the emergence of the B.1.1.7 variant in the United States. As of 12 January, 2021, neither the B.1.351 nor the P.1 variants have been detected in the United States. For information about emerging SARS-CoV-2 variants of concern, CDC maintains a webpage dedicated to providing information on emerging SARS-CoV-2 variants. The B.1.1.7 variant has a mutation in the S protein that affects the binding domain of the receptor. It also has 13 other lineage-defining variants that are related to the S protein. These variants, which include a deletion at position 69 and 70, have been known to cause S-gene target failure. Multiple lines of evidence show that B.1.1.7 is a more efficiently transmitted variant of SARS-CoV-2 than other variants. In the UK, infections with this variant were more common than those with other variants. The potential increase in the number of cases of B.1.1.7 in the U.S. could affect the trajectory of the pandemic. A simple two-variant compartmental model has been developed to model this phenomenon. The potential impact of vaccinations was simulated assuming that 1 million doses were administered each day starting in 2021. It was estimated that 95% immunity was achieved 14 to 30 days after receiving 2 doses, and although B.1.1.7 is still the dominant strain, its transmission was significantly reduced after becoming the dominant variant. Currently, there is no evidence that the COVID-19 variants cause better clinical outcomes than the SARS-CoV-2 strains. However, a higher transmission rate increases the number of patients requiring hospitalisation, which could result in more deaths. The experiences of the UK and the B.1.1.7 variant illustrate the importance of having a coordinated and comprehensive approach to control the spread of this highly contagious variant. This approach involves the use of both mitigation and vaccination measures. The increased transmissibility of B.1.1.7 warrants the implementation of robust public health strategies to minimize its impact and prevent further spread. Data from the Centers for Disease Control and Prevention show that increasing the use of effective mitigation measures, such as vaccinations, is critical to curbing the spread of the disease.

15.
J Infect Dis ; 224(2): 207-217, 2021 07 15.
Article in English | MEDLINE | ID: covidwho-1310923

ABSTRACT

We combined viral genome sequencing with contact tracing to investigate introduction and evolution of severe acute respiratory syndrome coronavirus 2 lineages in Santa Clara County, California, from 27 January to 21 March 2020. From 558 persons with coronavirus disease 2019, 101 genomes from 143 available clinical samples comprised 17 lineages, including SCC1 (n = 41), WA1 (n = 9; including the first 2 reported deaths in the United States, with postmortem diagnosis), D614G (n = 4), ancestral Wuhan Hu-1 (n = 21), and 13 others (n = 26). Public health intervention may have curtailed the persistence of lineages that appeared transiently during February and March. By August, only D614G lineages introduced after 21 March were circulating in Santa Clara County.


Subject(s)
COVID-19/epidemiology , COVID-19/transmission , SARS-CoV-2/genetics , Adult , Aged , COVID-19/prevention & control , California/epidemiology , Contact Tracing , Female , Genetic Variation , Genome, Viral/genetics , Genotype , Humans , Male , Middle Aged , Phylogeny , Risk Factors , SARS-CoV-2/classification , Travel , Young Adult
16.
N Engl J Med ; 385(4): 320-329, 2021 07 22.
Article in English | MEDLINE | ID: covidwho-1287848

ABSTRACT

BACKGROUND: Information is limited regarding the effectiveness of the two-dose messenger RNA (mRNA) vaccines BNT162b2 (Pfizer-BioNTech) and mRNA-1273 (Moderna) in preventing infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and in attenuating coronavirus disease 2019 (Covid-19) when administered in real-world conditions. METHODS: We conducted a prospective cohort study involving 3975 health care personnel, first responders, and other essential and frontline workers. From December 14, 2020, to April 10, 2021, the participants completed weekly SARS-CoV-2 testing by providing mid-turbinate nasal swabs for qualitative and quantitative reverse-transcriptase-polymerase-chain-reaction (RT-PCR) analysis. The formula for calculating vaccine effectiveness was 100% × (1 - hazard ratio for SARS-CoV-2 infection in vaccinated vs. unvaccinated participants), with adjustments for the propensity to be vaccinated, study site, occupation, and local viral circulation. RESULTS: SARS-CoV-2 was detected in 204 participants (5%), of whom 5 were fully vaccinated (≥14 days after dose 2), 11 partially vaccinated (≥14 days after dose 1 and <14 days after dose 2), and 156 unvaccinated; the 32 participants with indeterminate vaccination status (<14 days after dose 1) were excluded. Adjusted vaccine effectiveness was 91% (95% confidence interval [CI], 76 to 97) with full vaccination and 81% (95% CI, 64 to 90) with partial vaccination. Among participants with SARS-CoV-2 infection, the mean viral RNA load was 40% lower (95% CI, 16 to 57) in partially or fully vaccinated participants than in unvaccinated participants. In addition, the risk of febrile symptoms was 58% lower (relative risk, 0.42; 95% CI, 0.18 to 0.98) and the duration of illness was shorter, with 2.3 fewer days spent sick in bed (95% CI, 0.8 to 3.7). CONCLUSIONS: Authorized mRNA vaccines were highly effective among working-age adults in preventing SARS-CoV-2 infection when administered in real-world conditions, and the vaccines attenuated the viral RNA load, risk of febrile symptoms, and duration of illness among those who had breakthrough infection despite vaccination. (Funded by the National Center for Immunization and Respiratory Diseases and the Centers for Disease Control and Prevention.).


Subject(s)
COVID-19 Vaccines , COVID-19/prevention & control , Viral Load , Adolescent , Adult , COVID-19/diagnosis , COVID-19/virology , COVID-19 Nucleic Acid Testing , COVID-19 Vaccines/immunology , Carrier State/diagnosis , Carrier State/prevention & control , Emergency Responders , Female , Health Personnel , Humans , Male , Middle Aged , Patient Acuity , Prospective Studies , SARS-CoV-2/isolation & purification , Treatment Outcome , Young Adult
18.
Clin Infect Dis ; 72(10): e448-e457, 2021 05 18.
Article in English | MEDLINE | ID: covidwho-1232180

ABSTRACT

BACKGROUND: The Diamond Princess cruise ship was the site of a large outbreak of coronavirus disease 2019 (COVID-19). Of 437 Americans and their travel companions on the ship, 114 (26%) tested positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). METHODS: We interviewed 229 American passengers and crew after disembarkation following a ship-based quarantine to identify risk factors for infection and characterize transmission onboard the ship. RESULTS: The attack rate for passengers in single-person cabins or without infected cabinmates was 18% (58/329), compared with 63% (27/43) for those sharing a cabin with an asymptomatic infected cabinmate, and 81% (25/31) for those with a symptomatic infected cabinmate. Whole genome sequences from specimens from passengers who shared cabins clustered together. Of 66 SARS-CoV-2-positive American travelers with complete symptom information, 14 (21%) were asymptomatic while on the ship. Among SARS-CoV-2-positive Americans, 10 (9%) required intensive care, of whom 7 were ≥70 years. CONCLUSIONS: Our findings highlight the high risk of SARS-CoV-2 transmission on cruise ships. High rates of SARS-CoV-2 positivity in cabinmates of individuals with asymptomatic infections suggest that triage by symptom status in shared quarters is insufficient to halt transmission. A high rate of intensive care unit admission among older individuals complicates the prospect of future cruise travel during the pandemic, given typical cruise passenger demographics. The magnitude and severe outcomes of this outbreak were major factors contributing to the Centers for Disease Control and Prevention's decision to halt cruise ship travel in US waters in March 2020.


Subject(s)
COVID-19 , Ships , Diamond , Disease Outbreaks , Humans , Quarantine , SARS-CoV-2 , Travel , United States/epidemiology
19.
J Infect Dis ; 224(2): 207-217, 2021 07 15.
Article in English | MEDLINE | ID: covidwho-1203708

ABSTRACT

We combined viral genome sequencing with contact tracing to investigate introduction and evolution of severe acute respiratory syndrome coronavirus 2 lineages in Santa Clara County, California, from 27 January to 21 March 2020. From 558 persons with coronavirus disease 2019, 101 genomes from 143 available clinical samples comprised 17 lineages, including SCC1 (n = 41), WA1 (n = 9; including the first 2 reported deaths in the United States, with postmortem diagnosis), D614G (n = 4), ancestral Wuhan Hu-1 (n = 21), and 13 others (n = 26). Public health intervention may have curtailed the persistence of lineages that appeared transiently during February and March. By August, only D614G lineages introduced after 21 March were circulating in Santa Clara County.


Subject(s)
COVID-19/epidemiology , COVID-19/transmission , SARS-CoV-2/genetics , Adult , Aged , COVID-19/prevention & control , California/epidemiology , Contact Tracing , Female , Genetic Variation , Genome, Viral/genetics , Genotype , Humans , Male , Middle Aged , Phylogeny , Risk Factors , SARS-CoV-2/classification , Travel , Young Adult
20.
Clin Infect Dis ; 2021 Apr 17.
Article in English | MEDLINE | ID: covidwho-1189442

ABSTRACT

BACKGROUND: To inform prevention strategies, we assessed the extent of SARS-CoV-2 transmission and settings in which transmission occurred in a Georgia public school district. METHODS: During December 1, 2020-January 22, 2021, SARS-CoV-2-infected index cases and their close contacts in schools were identified by school and public health officials. For in-school contacts, we assessed symptoms and offered SARS-CoV-2 RT-PCR testing; performed epidemiologic investigations and whole-genome sequencing to identify in-school transmission; and calculated secondary attack rate (SAR) by school setting (e.g., sports, elementary school classroom), index case role (i.e., staff, student), and index case symptomatic status. RESULTS: We identified 86 index cases and 1,119 contacts, 688 (63.1%) of whom received testing. Fifty-nine (8.7%) of 679 contacts tested positive; 15 (17.4%) of 86 index cases resulted in ≥2 positive contacts. Among 55 persons testing positive with available symptom data, 31 (56.4%) were asymptomatic. Highest SAR were in indoor, high-contact sports settings (23.8%, 95% confidence interval [CI] 12.7, 33.3), staff meetings/lunches (18.2%, CI 4.5-31.8), and elementary school classrooms (9.5%, CI 6.5-12.5). SAR was higher for staff (13.1%, CI 9.0-17.2) versus student index cases (5.8%, CI 3.6-8.0) and for symptomatic (10.9%, CI 8.1-13.9) versus asymptomatic index cases (3.0%, CI 1.0-5.5). CONCLUSIONS: Indoor sports may pose a risk to the safe operation of in-person learning. Preventing infection in staff members, through measures that include COVID-19 vaccination, is critical to reducing in-school transmission. Because many positive contacts were asymptomatic, contact tracing should be paired with testing, regardless of symptoms.

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