Covid-19 sars-coV-2 Lisa Gilbert, md, faafp, ctropMed 3/17/20 covid-19 sars-coV-2 2019-nCov hcoV-19



Yüklə 15,76 Kb.
səhifə3/6
tarix07.01.2024
ölçüsü15,76 Kb.
#202382
1   2   3   4   5   6
covid-19

SARS-Cov-2 Transmission

  • Novel: No herd immunity, No antibodies cross-reacting
  • Incubation 2-14 days (outlier 27 days)
    • Symptom onset median: Day 5-6 from exposure
  • Doubling time: 6-7 days
  • High viral shedding occurs early in disease course, even those with mild symptoms
  • Prolonged shedding noted (unlikely reinfection)
  • ? Up to 23% of transmissions due to pre-symptomatic cases in Shenzen
  • True asymptotic cases apparently only 1% per WHO?
    • Viral load apparently still high
    • Apparently infectious?
    • https://cmmid.github.io/topics/covid19/control-measures/pre-symptomatic-transmission.html

      https://www.who.int/docs/default-source/coronaviruse/who-china-joint-mission-on-covid-19-final-report.pdf

SARS-Cov-2 Transmission

  • Respiratory droplets (large - 3 ft, medium - 6 ft)
  • Hand-to-mucus-membrane contact – sticks to skin easily!
    • T-zone: eyes, nose, mouth vulnerable
  • Viable for 3 days on solids (plastics, porcelain, steel); ~24 hours cardboard, dependent also on temperature/humidity; 3 hours if aerosolized
  • Airborne – likely not airborne with cough? But certainly possible with intubation, non-invasive positive pressure ventilation, high flow O2, nebulizer, suctioning
  • ?Fecal/oral? – viral shedding present in stool and diarrhea is common
  • https://www.medrxiv.org/content/10.1101/2020.03.09.20033217v1.full.pdf


https://www.ajicjournal.org/article/S0196-6553(16)30531-4/pdf

Seasonality and Mutation Rate

  • We don’t know.
  • Some CoV are seasonal in northern hemisphere; MERS is not.
  • High disease burden and outbreaks obscure seasonality.
  • Typical viral mutation rate; see NextStrain for real time gene sequencing: https://nextstrain.org/
    • Major strain development: L type (more virulent) and S type (wild type/apparent first strain). Lethality difference unclear.
  • Normally viruses become more benign over time. However, delayed symptom onset, delayed time to death, poor access to diagnosis with isolation, contact tracing and quarantine makes deadly strains persist.

Yüklə 15,76 Kb.

Dostları ilə paylaş:
1   2   3   4   5   6




Verilənlər bazası müəlliflik hüququ ilə müdafiə olunur ©azkurs.org 2024
rəhbərliyinə müraciət

gir | qeydiyyatdan keç
    Ana səhifə


yükləyin