Transmission dynamics and timing of key events for SARS-CoV-2 infection in healthcare workers

Emecen, Ahmet Naci; Şensoy, Ecem Başoğlu; Sezgin, Edanur; Ustuner, Buket Yildirim; Keskin, Salih; Şiyve, Neslişah; ÇELİK, Saadet Göksu; Bayrak, Gamze; Durukan, Nurcan Şentürk; Beyan, Ayşe Coşkun; Ergör, Alp; Unal, Belgin; Ergör, Gül

doi:10.1080/23744235.2021.1900599

Cited by 6 publications

(6 citation statements)

References 28 publications

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“…Quality assessment (Additional file 1 : Table S4 [ 9 , 10 , 12 , 13 , 21 , 22 , 26 – 32 , 34 , 37 – 40 , 42 – 60 , 62 – 65 , 67 – 71 , 73 , 74 , 76 , 78 – 86 , 89 , 90 , 92 – 94 , 97 – 99 , 101 – 107 , 109 – 115 , 117 – 121 , 123 – 128 , 130 , 131 , 133 , 136 – 139 , 141 – 153 , 155 – 161 , 164 – 166 ]) indicated that 1 study provided a precise exposure window for cases and identification of the potential infector(s). Sixty-eight studies included a well-characterized cohort of individuals that were comparable with the population and provided precise estimates for the symptom onset window for themselves and their potential infector(s).…”

Section: Resultsmentioning

confidence: 99%

“…4 , Additional file 1 : Fig. S3 [ 9 , 10 , 12 , 13 , 21 , 27 – 31 , 34 , 37 – 39 , 44 – 51 , 53 , 54 , 56 , 57 , 59 , 60 , 63 , 64 , 67 , 68 , 71 , 76 , 79 , 81 – 84 , 89 , 90 , 93 , 94 , 98 , 99 , 106 , 109 , 110 , 119 – 121 , 123 , 124 , 126 – 128 , 131 , 133 , 136 – 139 , 141 , 142 , 144 – 153 , 156 – 158 , 160 , 161 , 164 – 166 ]). Five studies did not specify the Omicron subvariant, and their pooled mean was 3.71 days (95% CI: 2.93–4.49 days); by pooling the estimates of the Omicron subvariants, the mean incubation period was 3.19 days (95% CI: 2.95–3.43 days).…”

Section: Resultsmentioning

confidence: 99%

“…Our results suggested no potential publication bias in the included studies ( p -value: 0.700) (Additional file 1 : Fig. S4 [ 9 , 10 , 12 , 13 , 21 , 27 – 31 , 34 , 37 – 39 , 44 – 51 , 53 , 54 , 56 , 57 , 59 , 60 , 63 , 64 , 67 , 68 , 71 , 76 , 79 , 81 – 84 , 89 , 90 , 93 , 94 , 98 , 99 , 106 , 109 , 110 , 119 – 121 , 123 , 124 , 126 – 128 , 131 , 133 , 136 – 139 , 141 , 142 , 144 – 153 , 156 – 158 , 160 , 161 , 164 – 166 ]).

Fig.…”

Section: Resultsmentioning

confidence: 99%

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Assessing changes in incubation period, serial interval, and generation time of SARS-CoV-2 variants of concern: a systematic review and meta-analysis

Xu,

Wu,

Kummer

et al. 2023

BMC Med

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Background After the first COVID-19 wave caused by the ancestral lineage, the pandemic has been fueled from the continuous emergence of new SARS-CoV-2 variants. Understanding key time-to-event periods for each emerging variant of concern is critical as it can provide insights into the future trajectory of the virus and help inform outbreak preparedness and response planning. Here, we aim to examine how the incubation period, serial interval, and generation time have changed from the ancestral SARS-CoV-2 lineage to different variants of concern. Methods We conducted a systematic review and meta-analysis that synthesized the estimates of incubation period, serial interval, and generation time (both realized and intrinsic) for the ancestral lineage, Alpha, Beta, and Omicron variants of SARS-CoV-2. Results Our study included 280 records obtained from 147 household studies, contact tracing studies, or studies where epidemiological links were known. With each emerging variant, we found a progressive shortening of each of the analyzed key time-to-event periods, although we did not find statistically significant differences between the Omicron subvariants. We found that Omicron BA.1 had the shortest pooled estimates for the incubation period (3.49 days, 95% CI: 3.13–4.86 days), Omicron BA.5 for the serial interval (2.37 days, 95% CI: 1.71–3.04 days), and Omicron BA.1 for the realized generation time (2.99 days, 95% CI: 2.48–3.49 days). Only one estimate for the intrinsic generation time was available for Omicron subvariants: 6.84 days (95% CrI: 5.72–8.60 days) for Omicron BA.1. The ancestral lineage had the highest pooled estimates for each investigated key time-to-event period. We also observed shorter pooled estimates for the serial interval compared to the incubation period across the virus lineages. When pooling the estimates across different virus lineages, we found considerable heterogeneities (I2 > 80%; I2 refers to the percentage of total variation across studies that is due to heterogeneity rather than chance), possibly resulting from heterogeneities between the different study populations (e.g., deployed interventions, social behavior, demographic characteristics). Conclusions Our study supports the importance of conducting contact tracing and epidemiological investigations to monitor changes in SARS-CoV-2 transmission patterns. Our findings highlight a progressive shortening of the incubation period, serial interval, and generation time, which can lead to epidemics that spread faster, with larger peak incidence, and harder to control. We also consistently found a shorter serial interval than incubation period, suggesting that a key feature of SARS-CoV-2 is the potential for pre-symptomatic transmission. These observations are instrumental to plan for future COVID-19 waves.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Fig.…”

Section: Resultsmentioning

confidence: 99%

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Assessing changes in incubation period, serial interval, and generation time of SARS-CoV-2 variants of concern: a systematic review and meta-analysis

Xu,

Wu,

Kummer

et al. 2023

BMC Med

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“…Increased case finding during outbreaks may also explain the differences in incident rates seen. Emecen and colleagues [20] showed that the serial interval and incubation periods of COVID-19 in HCWs were shorter than in the general population, which they suggest could be attributable to more rigorous contact tracing and isolation of infected HCWs [20]. Nonetheless, higher rates in HCWs with more extensive physical contact with patients (e.g.…”

Section: Plos Onementioning

confidence: 99%

Infection control, occupational and public health measures including mRNA-based vaccination against SARS-CoV-2 infections to protect healthcare workers from variants of concern: A 14-month observational study using surveillance data

et al. 2021

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Background We evaluated measures to protect healthcare workers (HCWs) in Vancouver, Canada, where variants of concern (VOC) went from <1% VOC in February 2021 to >92% in mid-May. Canada has amongst the longest periods between vaccine doses worldwide, despite Vancouver having the highest P.1 variant rate outside Brazil. Methods With surveillance data since the pandemic began, we tracked laboratory-confirmed SARS-CoV-2 infections, positivity rates, and vaccine uptake in all 25,558 HCWs in Vancouver Coastal Health, by occupation and subsector, and compared to the general population. Cox regression modelling adjusted for age and calendar-time calculated vaccine effectiveness (VE) against SARS-CoV-2 in fully vaccinated (≥ 7 days post-second dose), partially vaccinated infection (after 14 days) and unvaccinated HCWs; we also compared with unvaccinated community members of the same age-range. Findings Only 3.3% of our HCWs became infected, mirroring community rates, with peak positivity of 9.1%, compared to 11.8% in the community. As vaccine coverage increased, SARS-CoV-2 infections declined significantly in HCWs, despite a surge with predominantly VOC; unvaccinated HCWs had an infection rate of 1.3/10,000 person-days compared to 0.89 for HCWs post first dose, and 0.30 for fully vaccinated HCWs. VE compared to unvaccinated HCWs was 37.2% (95% CI: 16.6–52.7%) 14 days post-first dose, 79.2% (CI: 64.6–87.8%) 7 days post-second dose; one dose provided significant protection against infection until at least day 42. Compared with community infection rates, VE after one dose was 54.7% (CI: 44.8–62.9%); and 84.8% (CI: 75.2–90.7%) when fully vaccinated. Interpretation Rigorous droplet-contact precautions with N95s for aerosol-generating procedures are effective in preventing occupational infection in HCWs, with one dose of mRNA vaccination further reducing infection risk despite VOC and transmissibility concerns. Delaying second doses to allow more widespread vaccination against severe disease, with strict public health, occupational health and infection control measures, has been effective in protecting the healthcare workforce.

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“…Increased case finding during outbreaks may also explain the differences in incident rates seen. Emecen and colleagues (20) showed that the serial interval and incubation periods of COVID-19 in HCWs were shorter than in the general population, which they suggest could be attributable to more rigorous contact tracing and isolation of infected HCWs (20).…”

Section: Discussionmentioning

confidence: 99%

Infection control, occupational and public health measures including mRNA-based vaccination against SARS-CoV-2 infections to protect healthcare workers from variants of concern: a 14-month observational study using surveillance data

Yassi

Grant

Lockhart

et al. 2021

Preprint

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Background: We evaluated measures to protect healthcare workers (HCWs) in Vancouver, Canada, where variants of concern (VOC) went from <1% in February 2021 to >92% in mid-May. Canada has amongst the longest periods between vaccine doses worldwide, despite Vancouver having the highest P.1 variant rate outside Brazil. Methods: With surveillance data since the pandemic began, we tracked laboratory-confirmed SARS-CoV-2 infections, positivity rates, and vaccine uptake in all 25,558 HCWs in Vancouver Coastal Health, by occupation and subsector, and compared to the general population. We employed Cox regression modelling adjusted for age and calendar-time to calculate vaccine effectiveness (VE) against SARS-CoV-2 in fully vaccinated (≥ 7 days post-second dose), partially vaccinated (14 days post vaccine) and unvaccinated HCWs; we also compared with unvaccinated community members of the same age-range. Findings: Only 3.3% of our HCWs became infected, mirroring community rates, with peak positivity of 9.1%, compared to 11.8% in the community. As vaccine coverage increased, SARS-CoV-2 infections declined significantly in HCWs, despite a surge with predominantly VOC; unvaccinated HCWs had an infection rate of 1.3/10,000 person-days compared to 0.89 for HCWs post first dose, and 0.30 for fully vaccinated HCWs. VE compared to unvaccinated HCWs was 37.2% (95% CI: 16.6-52.7%) 14 days post-first dose, 79.2% (CI: 64.6-87.8%) 7 days post-second dose; one dose provided significant protection against infection until at least day 42. Compared with community infection rates, VE after one dose was 54.7% (CI: 44.8-62.9%); and 84.8% (CI: 75.2-90.7%) when fully vaccinated. Interpretation: Predominantly droplet-contact precautions, with N95s required for aerosol generating medical procedures and available as needed according to point-of-care risk assessment, has been a highly effective approach to preventing occupational infection in HCWs, with one dose of mRNA vaccination further reducing infection risk despite VOC and transmissibility concerns. Delaying second doses to allow more widespread vaccination against severe disease, with strict public health, occupational health and infection control measures, has been effective in protecting the healthcare workforce.

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Transmission dynamics and timing of key events for SARS-CoV-2 infection in healthcare workers

Cited by 6 publications

References 28 publications

Assessing changes in incubation period, serial interval, and generation time of SARS-CoV-2 variants of concern: a systematic review and meta-analysis

Assessing changes in incubation period, serial interval, and generation time of SARS-CoV-2 variants of concern: a systematic review and meta-analysis

Infection control, occupational and public health measures including mRNA-based vaccination against SARS-CoV-2 infections to protect healthcare workers from variants of concern: A 14-month observational study using surveillance data

Infection control, occupational and public health measures including mRNA-based vaccination against SARS-CoV-2 infections to protect healthcare workers from variants of concern: a 14-month observational study using surveillance data

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