Shorter Incubation Period among Unvaccinated Delta Variant Coronavirus Disease 2019 Patients in Japan

Ogata, Tsuyoshi; Tanaka, Hideo; Irie, Fujiko; Hirayama, Atsushi; Takahashi, Yuki

doi:10.3390/ijerph19031127

Cited by 26 publications

(28 citation statements)

References 29 publications

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“…113 Another study reported the incubation period of COVID-19 caused by the Beta/Gamma variant was 5.10 days (95% CI, 4.87-5.33 days). 35 A total of 6 studies reported the incubation period of COVID-19 caused by the Delta variant, including 2 from China, 63,152 2 from Japan, 80,112 1 from France, 35 and 1 from Spain, 26 with a pooled incubation period of 4.41 days (95% CI, 3.76-5.05 days) (Figure 2). Five studies reported the incubation period of COVID-19 caused by the Omicron variant-1 each from Norway, 20 Spain, 26 Japan, 112 the Netherlands, 17 and South Korea 59 -with a pooled incubation period of 3.42 days (95% 2).…”

Section: Mean Incubation Periods Of Covid-19 Infected By Different St...mentioning

confidence: 99%

Incubation Period of COVID-19 Caused by Unique SARS-CoV-2 Strains

et al. 2022

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Section: Mean Incubation Periods Of Covid-19 Infected By Different St...mentioning

confidence: 99%

Incubation Period of COVID-19 Caused by Unique SARS-CoV-2 Strains

et al. 2022

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“…It was shown that the incubation period of SARS-CoV-2 differs from variant to another (Table 1 ). The incubation period for the Delta variant, to the best of our knowledge, was only reported in four studies from China and Japan [ 74 – 77 ]. It was significantly shorter (3.7, 4.0 and 4.4 days) than for non-Delta strains (4.9–6.0 days) [ 74 – 76 ].…”

Section: Incubation Periodmentioning

confidence: 99%

“…The incubation period for the Delta variant, to the best of our knowledge, was only reported in four studies from China and Japan [ 74 – 77 ]. It was significantly shorter (3.7, 4.0 and 4.4 days) than for non-Delta strains (4.9–6.0 days) [ 74 – 76 ]. However, in another study, a longer incubation period was reported (6.0 days) [ 77 ].…”

Section: Incubation Periodmentioning

confidence: 99%

SARS-CoV-2 infection in pediatric population before and during the Delta (B.1.617.2) and Omicron (B.1.1.529) variants era

Khemiri

Ayouni

Triki

et al. 2022

Virol J

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Background COVID-19, the coronavirus disease that emerged in December 2019, caused drastic damage worldwide. At the beginning of the pandemic, available data suggested that the infection occurs more frequently in adults than in infants. In this review, we aim to provide an overview of SARS-CoV-2 infection in children before and after B.1.617.2 Delta and B.1.1.529 Omicron variants emergence in terms of prevalence, transmission dynamics, clinical manifestations, complications and risk factors. Methods Our method is based on the literature search on PubMed, Science Direct and Google Scholar. From January 2020 to July 2022, a total of 229 references, relevant for the purpose of this review, were considered. Results The incidence of SARS-CoV-2 infection in infants was underestimated. Up to the first half of May, most of the infected children presented asymptomatic or mild manifestations. The prevalence of COVID-19 varied from country to another: the highest was reported in the United States (22.5%). COVID-19 can progress and become more severe, especially with the presence of underlying health conditions. It can also progress into Kawasaki or Multisystem Inflammatory Syndrome (MIS) manifestations, as a consequence of exacerbating immune response. With the emergence of the B.1.617.2 Delta and B.1.1.529 Omicron variants, it seems that these variants affect a large proportion of the younger population with the appearance of clinical manifestations similar to those presented by adults with important hospitalization rates. Conclusion The pediatric population constitutes a vulnerable group that requires particular attention, especially with the emergence of more virulent variants. The increase of symptomatic SARS-CoV-2 infection and hospitalization rate among children highlights the need to extend vaccination to the pediatric population.

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“…The omicron variant was significantly shorter than that of alpha, delta SI had an intermediate value. These results are surprising as the delta variant R 0 is 1.8 times that of the alpha variant and the omicron variant infectivity is 2.8 times that of delta variant, even if SI among unvaccinated delta variant was not found to be significant from that of unvaccinated non delta variant in one study [2,7,94]. These discrepancies can likely be explained by unvaccinated or "remaining to vaccinate" population either more exposed or more susceptible to new variants, a weaker vaccine effectiveness for delta and omicron variants, and epidemiological surveillance and contact tracing more efficient in their organisation and availability of screening tests throughout the epidemic.…”

Section: Discussionmentioning

confidence: 99%

An update of serial interval estimates for COVID-19: a meta-analysis

Jusot

2022

4open

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Background: Serial interval (SI) is one of the most important parameter for COVID-19 modelling purposes as it is related to the reproduction rate of the infection. The first meta-analysis of serial interval were performed with a range of uncertainty in the estimate. This meta-analysis aimed to reduce the uncertainty estimates by assessing publications over a longer period. Methods: A literature search was performed for articles published between 1st December 2019 and 15th February 2022. It retrieved 117 eligible studies containing some 80 for 90 serial interval estimates. A random effects model was used. Heterogeneity was checked. To detect a publication bias, a funnel plot was performed using an Egger’s test. Results: For alpha variant, the serial interval was estimated at 5.17 days (95% CI = 4.87 – 5.47) with a significant heterogeneity (I2 = 97.1%). The meta-analysis did not exhibit evident publication bias (Egger’s test = −0.55, p = 0.58). The meta-analysis allowed for reducing uncertainty in estimating the serial interval, although subgroup analysis did not reduce it sufficiently and showed that studies using a gamma distribution of serial intervals exhibited the highest estimate of 5.6 days. Compared to the other variants of concern, alpha serial interval estimate was bigger than delta, 4.07 days, and omicron, 3.06 days. Conclusion: The meta-analysis was carried out as a real-time monitoring of this parameter to make a choice and a rapid assessment of the control measures implemented, and the effectiveness of the vaccination campaign. The meta-analysis was unable to provide a suitable estimate of serial intervals for COVID-19 modelling purposes although its uncertainty was reduced. Furthermore, serial intervals estimate for alpha variant was close to earlier reports and lower than previous publications, respectively. Another limitation is, that meta-analysis of COVID pandemic studies in principle contains and produces itself a significant source of heterogeneity.

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Shorter Incubation Period among Unvaccinated Delta Variant Coronavirus Disease 2019 Patients in Japan

Cited by 26 publications

References 29 publications

Incubation Period of COVID-19 Caused by Unique SARS-CoV-2 Strains

Incubation Period of COVID-19 Caused by Unique SARS-CoV-2 Strains

SARS-CoV-2 infection in pediatric population before and during the Delta (B.1.617.2) and Omicron (B.1.1.529) variants era

An update of serial interval estimates for COVID-19: a meta-analysis

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