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COVID-19: in the footsteps of Ernest Shackleton
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  • Published on:
    Covid-19: in the footsteps of Ernest Shackleton. Asymptomatic passengers and crew
    • Alvin Ing, Respiratory Physician Macquarie University

    Thank you for inviting us to respond to correspondence from Dr. Andrea Vila, entitled “Active searching for pseudo-asymptomatic contacts during outbreak, as containment measure”.

    We would like to establish in greater details what we defined as “asymptomatic” on board our cruise ship. For the first 8 days, prior to the development of fever in the first subject, our 2 ship’s physicians regularly checked for fever in all passengers in a common area, and attended to calls which were predominantly for sea sickness. After day 8, all passengers and crew were seen by one of the two ship’s physicians twice daily, and had body temperature checks. During these visits, symptoms were enquired about. This includes fever, sore throat, cough and myalgias. In mid-March, anosmia was a recognised symptom of Covid-19 infection and was thus included, but dysgeusia and ageusia were not, and thus Vila makes a valid point. However, given that all passengers and crew were seen twice daily between day 8 and day 28, we are confident in the accuracy of the data presented (81% of Covid-19 subjects being asymptomatic), with the above rider. We do not feel that language was a barrier in communication, with the overwhelming number of passengers and crew either having English as their native language, or being fluent in English. In addition one of the ship’s physicians was multilingual.

    Vila also accurately states that asymptomatic subjects may be pre-symptomatic. We have follow-up on all p...

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    Conflict of Interest:
    None declared.
  • Published on:
    Active searching for ¨pseudo-asymptomatic¨ contacts during outbreak, as containment measure.
    • Andrea Vila, Infectious Diseases Specialist Hospital Italiano de Mendoza

    Dear Editor,
    Ing and colleagues reported a cruise outbreak in which a high prevalence of asymptomatic SARS-coV-2 infection was noticed. Viral shedding can occur in the absence of symptoms and before symptom onset, and asymptomatic patients represent an epidemiological problem of great public health significance. However, it’s noteworthy that the huge number of asymptomatic patients (81%), contrasts with a high percentage of severe illness (9.4%) reported on the population of the cruise ship. So, there seems to be a gap between asymptomatic and severe cases of COVID-19, with just 9.6% of mild and moderate clinically disease.
    Cluster studies conducted in Singapore attributed 6.4% to asymptomatic transmission 1.
    Possibly great part of the population of asymptomatic cases, could have been symptomatic but not meeting the ¨case definition¨ at that time, or pre-symptomatic cases (probably the patients had no evaluation after arrival).
    Initial case definition has been periodically updated as more knowledge about COVID-19 was available 2, adding mild or atypical symptoms such as diarrhea, constitutional symptoms, sudden onset of anosmia, ageusia or dysgeusia. The latter were recognized in late March and published in April, thus scarcely known at the time of the report 3-5. As of June, it has been reported that up to 83% patients with mild illness develop anosmia (without nasal obstruction) or dysgeusia as an early or initial manifestation in the absence of o...

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    Conflict of Interest:
    None declared.