Transmission

Last updated: 2021 Dec 15
Total hit(s): 30
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During the second wave in Mexico, the B.1.519 variant was the most prevalent, however the Delta variant, once imported, accounted for 78 percent of all Covid-19 cases. In the third wave, the Delta variety overtookthe B.1.1519 variant in this Mexico population, demonstrating overall superior fitness. It wasfound that younger people were moreimpacted, with a mean age of 30 years old, in all COVID-19 positive samples , and there was no gender bias in this cohort.
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 		Pre-print (medRXiv)
Date of Publishing 2021 Oct 20
Title SARS-CoV-2 variant transmission in a community-health population (Mexico City, Mexico)
Impact factor
N/A
Date of Entry 2021 Dec 15

The generation time of the Delta variant (4.6 days) between two infections was shorter than that of the Alpha variant (5.5 days), resulting in faster transmission of the Delta variant. Effect of SARS-CoV-2 variants on household generation time was more prominent than effect of vaccination status or age of patients.
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 		Pre-print (medRXiv)
Date of Publishing 2021 Oct 23
Title Generation time of the Alpha and Delta SARS-CoV-2 variants
Impact factor
N/A
Date of Entry 2021 Nov 2

In early 2021, the emergence of the Delta variant was 37-163 % faster than the Alpha variant. Across New England, the Delta variant was estimated to be 58-120 % more transmissible than Alpha. A multiplicative increase in Rt estimates indicates that Delta had the greatest advantage in Maine (1.99x increase) and Vermont (1.87x increase), and the lowest advantage in New Hampshire (1.51x) and Massachusetts (1.45x).
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 		Pre-print (medRXiv)
Date of Publishing 2021 Oct 07
Title Comparative transmissibility of SARS-CoV-2 variants Delta and Alpha in New England, USA
Impact factor
N/A
Date of Entry 2021 Nov 2

Out of 46 COVID-19 positive individuals on a flight from New Delhi to Hong Kong, the Kappa variant (B.1.617.1) was linked to a cluster of 39 cases (84.8%), while the Delta variant (B.1.617.2) was reported in two passengers (4.3%). The Alpha variant (B.1.1.7) was detected in five passengers including a crew member (10.9%). One parent tested positive for Alpha whereas the infant tested positive for Kappa in a family of 3 (Travel group A). Similary, in a famly of 6 (Travel group B), a child tested positive for Alpha while2 children and 3 adults were infected with Kappa during travel.
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 		Pre-print (medRXiv)
Date of Publishing 2021 Jul 23
Title Air travel-related outbreak of multiple SARS-CoV-2 variants
Impact factor
N/A
Date of Entry 2021 Nov 2

As of April 2021, the Lambda Variant of Interest (C.37), which was initially discovered in South America in late 2020, accounted for 97% of Peruvian public genomes. It has been found in Colombia, Ecuador, Mexico, the United States, Germany, and Israel, and evidence of transmission has been found in Chile and Argentina. To assess its transmission, pathogenicity, and immune escape qualities, more epidemiological data and analysis are required.
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 		Pre-print ( medRXiv )
Date of Publishing 2021 Jul 03
Title The Emergence of SARS-CoV-2 Variant Lambda (C.37) in South America
Impact factor
N/A
Date of Entry 2021 Sep 30

For SARS-CoV-2 cused by Delata variant, the time interval between symptom onset of consecutive COVID-19 cases in a transmission chain was reduced from 4 days to 2.5 days. Faster spread of Delta variant was indicated since Reproductive number was above 1 during the study period. Factors such as Increased travel and impact of COVID-19 vaccination was not considered in the study.
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 		Pre-print ( medRXiv )
Date of Publishing 2021 Aug 20
Title Changes in the serial interval and transmission dynamics associated with the SARS-CoV-2 Delta variant in South Korea
Impact factor
N/A
Date of Entry 2021 Sep 30

Delta (B.1.617.2) variant of concern (VOC) and Gamma variant (P.1) had replaced the Alpha (B.1.1.7) variant of concern (VOC) as the major variant responsible for spread of SARS-CoV-2 in United States. Of these 2, Delta variantwas the most dominant variant responsible for spread of SARS-CoV-2. The transmission of Delta variant is higher in countries where vaccination is low. 1. The number of positive cases being tested reduced in last two months of study due to low test positivity rates. 2. Lack of homogeneity in the data across United States was noted.
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 		Pre-print ( medRXiv )
Date of Publishing 2021 Jun 21
Title Rapid displacement of SARS-CoV-2 variant B.1.1.7 by B.1.617.2 and P.1 in the United States
Impact factor
N/A
Date of Entry 2021 Sep 30

The study focuses on the prevalence of COVID 19 caused by Delta VOC or Alpha VOC in the population of Scotland. The Delta VOC was found to be mostly prevalent in younger, wealthier people.
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 		thelancet.com
Date of Publishing 2021 Jun 14
Title SARS-CoV-2 Delta VOC in Scotland: demographics, risk of hospital admission, and vaccine effectiveness
Impact factor
N/A
Date of Entry 2021 Sep 30

Rapid displacement of SARS-CoV-2 Alpha variant by the Delta variant in June-July 2021 was detected in Lebanon. The study confirmed international travel and community spread to be the transmission routes for this displacement. Travel restrictions and Public health measures were insufficient to prevent the spread of the SARS-CoV-2 variants. Rapid genomic sequencing was necessary to detect the otherwise silent transmisson of Delta variant in the community.
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 		Pre-print ( medRXiv )
Date of Publishing 2021 Aug 11
Title Replacement of the Alpha variant of SARS-CoV-2 by the Delta variant in Lebanon between April and June 2021
Impact factor
N/A
Date of Entry 2021 Sep 30

G-variant of the SARS-CoV-2 was highly prevalent in Brazil and the use of a SEIR model that could be used to predict future outbreaks in infected countries was highlighted in the study. The spread of COVID-19 in Brazil was taken as the first case study, where 2 lineages of SARS-CoV-2 and time-varying reproduction number were considered. Prediction of the second outbreak at end of 2020 was due to the release of NPIs across Brazil. The importance of NPIs, continuous genomic surveillance to monitor SARS-CoV-2 mutations in the development of immunological interventions was highlighted.
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 		Pre-print ( medRXiv )
Date of Publishing 2020 Dec 10
Title The Impact of SARS-CoV-2 Variant to COVID-19 Epidemic in Brazil
Impact factor
N/A
Date of Entry 2021 Sep 13

SARS-CoV-2 Delta variant presented the highest risk among the currently circulating strains, even in vaccinated individuals. Two Indian patients transmitted the Delta variant to 5 wedding guests in Houston, USA. The observations in the study indicate cases of vaccine breakthrough since there was no history of vaccine failure in the infected individuals.
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 		Pre-print ( medRXiv )
Date of Publishing 2021 Jul 04
Title Transmission event of SARS-CoV-2 Delta variant reveals multiple vaccine breakthrough infections
Impact factor
N/A
Date of Entry 2021 Aug 6

Delta variant, identified in India, was reported to be 60% more infectious than the wild type SARS-CoV-2. Lockdown measures and unfavourable weather conditions, rather than population immunity, were responsible for low infection rates. Delta variant was able to evade immunity from previous wild type infection during the first and second wave (for about 45.8% of the time).
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 		Pre-print ( medRXiv )
Date of Publishing 2021 Jun 25
Title COVID-19 pandemic dynamics in India and impact of the SARS-CoV-2 Delta (B.1.617.2) variant
Impact factor
N/A
Date of Entry 2021 Jul 2

SARS-CoV-2 Epsilon variant (B.1.427/B.1.429) found in California showed a 20% higher transmissibility and higher viral RNA loads being detected in patients compared to non-variants. No significant difference was found in Ct values between hospitalized patients and outpatients infected with B.1.427/B.1.429 variant or even non-variants.
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 		33991487
(Cell)
PMID
33991487
Date of Publishing: 2021 Jun 24
Title Transmission, infectivity, and neutralization of a spike L452R SARS-CoV-2 variant
Author(s) nameDeng X, Garcia-Knight MA et al.
Journal Cell
Impact factor
27.35
Citation count: 162
Date of Entry 2021 Jul 2

B.1.526 variant has surged rapidly across the New York state in mid-April, and now it can be found in all 50 states of the US as well as in other numerous countries. During the initial days of infection, B.1.526 variant increased rapidly in the population until B.1.1.7 variant showed its dominance with an estimated growth rate of 5.3% per day. B.1.1.7 variant had an overall fitness advantage of 12-15% than its competitor B.1.526. Hence, B.1.1.7 variant slowed down the growth of the B.1.526 variant. Cases of the B.1.526 variant started to decline rapidly in areas where the B.1.1.7 variant was reported.
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 		Pre-print ( medRXiv )
Date of Publishing 2021 Jun 12
Title A Novel and Expanding SARS-CoV-2 Variant, B.1.526, Identified in New York
Impact factor
N/A
Date of Entry 2021 Jul 2

The transmission of the SARS-CoV-2 Alpha variant (B.1.1.7) was exclusive to the US where the majority of COVID-19 transmission routes were contributed by California, Washington, and Ohio as compared to the other states. Super spreader events can be one of the possible reasons of sudden rise in cases.
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 		Pre-print ( medRXiv )
Date of Publishing 2021 May 18
Title Rapidly emerging SARS-CoV-2 B.1.1.7 sub-lineage in the United States of America with spike protein D178H and membrane protein V70L mutations
Impact factor
N/A
Date of Entry 2021 Jul 2

The emergence of N440K variant in several parts of India has been reported during the second wave of the pandemic. It has been concluded that the N440K variant has higher transmissibility rate than the other two prevalent strains (A2a and A3i) when they were compared on the basis of replicative fitness and infectivity. To get a thorough understanding of the penetration of N440K in the Indian population, whole genome sequencing of the viral samples should be carried out.
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 		Pre-print (bioRXiv)
Date of Publishing 2021 Apr 30
Title N440K variant of SARS-CoV-2 has Higher Infectious Fitness
Impact factor
N/A
Date of Entry 2021 Jul 2

First case of SARS-CoV-2 Alpha variant was detected In Japan on January 6, 2021, which was imported from UK with 60% higher infectiousness than the original strain. Possibility of a community outbreak was not unlikely in Japan 2 months after the detection of the first variant case, but could not be confirmed.
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 		Pre-print ( medRXiv )
Date of Publishing 2021 Apr 17
Title Estimating SARS-CoV-2 variant strain infectiousness in Japan as of March 28, 2021
Impact factor
N/A
Date of Entry 2021 Jul 2

The spread of Alpha variant in Switzerland increased due to its higher transmission fitness which was 43-52% more than that of the older circulating strains. Reproductive number for the Alpha variant was always above 1 while the non-Alpha strain showed a Ro below 1. The growth model predicted that there would be a rise in case numbers if the B.1.1.7 variant becomes predominant during the month of March in Switzerland. However, the model was not inclusive of the effects of lockdown measures, vaccination and infection-induced imuunity.
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 		Pre-print ( medRXiv )
Date of Publishing 2021 Apr 16
Title Quantification of spread of SARS-CoV-2 variant B.1.1.7 in Switzerland
Impact factor
N/A
Date of Entry 2021 Jul 2

3 regions in England reported a higher number of cases (34.6%) with the SARS-CoV-2 Alpha variant. However, the Alpha variant did not show higher transmission during lockdowns. But the prevalence of the Alpha variant in the samples increased over the study period (from 79% to 96%) due to failure in the detection of the spike gene target in RT-PCR tests. There is no need of changing the criteria for symptomatic COVID-19 testing.
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 		doi
Date of Publishing 2021 Apr 12
Title Changes in symptomatology, reinfection, and transmissibility associated with the SARS-CoV-2 variant B.1.1.7: an ecological study
Impact factor
N/A
Date of Entry 2021 Jul 2

It was observed that the SARS-CoV-2 named CAL.20C (B.1.427/B.1.429) variant originated in California and progressively spread to other US states and 29 other countries. The progressive geographical spread of the B.1.427/B.1.429 VOC from California to other US states and countries were found to be consistent with the other recent findings of their increased transmissibility relative to currently circulating strains.
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 		33821281
(bioRxiv)
PMID
33821281
Date of Publishing: 2021 Apr 1
Title SARS-CoV-2 immune evasion by variant B.1.427/B.1.429
Author(s) nameMcCallum M, Bassi J et al.
Journal bioRxiv
Impact factor
- n/a -
Citation count: 4
Date of Entry 2021 Jul 2

The increased prevalence of the SARS-CoV-2 Epsilon variant (B.1.427/B.1.429) in San Fransico had a higher rate of transmissibility than other variants that resulted in increased secondary household infections. Limitations : There were several limitations of the study; being done on a random basis without differentiatial selection of variants, improper classification of index cases and incomplete coverage of household tests
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 		33688689
(medRxiv)
PMID
33688689
Date of Publishing: 2021 Mar 3
Title Estimation of secondary household attack rates for emergent SARS-CoV-2 variants detected by genomic surveillance at a community-based testing site in San Francisco
Author(s) namePeng J, Mann SA et al.
Journal medRxiv
Impact factor
- n/a -
Citation count: 1
Date of Entry 2021 Jul 2

The rapid spread and rise in the 20E (EU1) variant cases were due to increased summer travelers from Spain and the lack of effective screening/restrictions despite having no transmission advantage over the circulating strains. Spain was likely to be the origin of 20E (EU1) introductions in most countries. A higher incidence of non-20E (EU1) variants towards the end of summer in Belgium might explain the low incidence of the 20E (EU1) variant in some countries (Belgium, France, Czech Republic).
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 		Pre-print ( medRXiv )
Date of Publishing 2021 Mar 24
Title Emergence and spread of a SARS-CoV-2 variant through Europe in the summer of 2020
Impact factor
N/A
Date of Entry 2021 Jul 2

Mathematical modelling studies showed that the frequency of emergence of new variants was fairly common in infected individuals. Most of these variants do not survive. The predominant variants are associated with higher infectiousness and super-spreader events soon after they are introduced in the general population. 1. The reason for predominance of certain variants is unknown. 2. Approximate outbreak sizes for introduction of new variations and secondary infections from a person infected with a new variant could not be predicted.
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 		Pre-print ( medRXiv )
Date of Publishing 2021 Mar 24
Title Early super-spreader events are a likely determinant of novel SARS-CoV-2 variant predominance
Impact factor
N/A
Date of Entry 2021 Jul 2

3 imported cases were reported from London to Madrid, Spain. One of these cases initiated a household transmission to 3 other individuals. In addition, 2 cases were identified without epidemiological association to the UK strain, indicating independent introduction. Sequence deposited at GISAID: EPI_ISL_756271, 756272, 756273 and 756274
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 		33685741
(Enferm Infecc Microbiol Clin (Engl Ed).)
PMID
33685741
Date of Publishing: 2021 Feb 19
Title First confirmation of importation and transmission in Spain of the newly identified SARS-CoV-2 B.1.1.7 variant
Journal Enferm Infecc Microbiol Clin (Engl Ed).
Impact factor
N/A
Date of Entry 2021 Jul 2

The SARS-CoV-2 Alpha variant (B.1.1.7) emerged around October,2020 in UK. It had a rapid epidemic growth and higher transmissibility relative to other variants and was declared as the Variant of Concern(VOC). The study was important to control the spread of a highly transmissible variant. Limitations : - data analyzed did not entirely represent SARS-CoV-2 infections, - the analysis was on relatively simple data using simple parsimonious assumptions, - the spatiotemporal correlation intrinsic in infectious disease data was not explicitly modelled.
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 		doi
Date of Publishing 2021 Jan 04
Title Transmission of SARS-CoV-2 Lineage B.1.1.7 in England: Insights from linking B.1.1.7 in England: Insights from linking epidemiological and genetic data.
Impact factor
N/A
Date of Entry 2021 Jul 2