COVID-19 MAY SPREAD EVEN BEFORE SYMPTOMS APPEAR

                Fever, cough and shortness of breath. Those are the three symptoms prominently listed on the World Health Organization's website under Coronavirus symptoms, but as case counts continue to rise in the United States and across the world, it's clear that Covid-19, causes a much wider range of symptoms, the more detailed descriptions of the illness that are emerging show how doctors and researchers are still learning about the disease in real time, the pandemic which was first reported just three months ago, Covid-19 can begin in similar ways among patients, regardless of a person's age or health status. One of the first major reports on Coronavirus symptoms was published by the WHO in February, following their mission to China, that report based on nearly 56,000 cases there, found the most common symptoms were fever 88%, dry cough 68% and nearly 40% of those patients experienced fatigue, shortness of breath, stomach issues and weakness were less common. Since this report, other symptoms related to Covid-19 have emerged, many patients who've either tested positive for Coronavirus or have been told by their physicians to assume they have it, also develop a headache and sore throat, others become sick to their stomach with nausea or diarrhea, some patients say they have no interest in eating, many report they are losing their senses of taste and smell, according to the British Rhino-logical Society, a small study published in Jama Ophthalmology added another potential Covid-19 warning sign: pink eye, also known as conjunctivitis, a third of the 38 patients in the report had the inflammatory eye condition, but it's also becoming more clear that some infected people spreading the virus don't have any symptoms at all, this phenomenon is called presymptomatic transmission which is also a known way that the flu spreads although it seems to be rare.
The presymptomatic transmission of Covid-19 might pose challenges for disease control, the first case of Coronavirus in Singapore was detected on January 23, 2020 and by March 16, a total of 243 cases had been confirmed, including 157 locally acquired cases, clinical and epidemiologic findings of all Covid-19 cases in Singapore through March 16 were reviewed to determine whether presymptomatic transmission might have occurred, it was defined as the transmission of Covid-19 from an infected person to a secondary patient before the source patient developed symptoms, as ascertained by exposure and symptom onset dates, with no evidence that the secondary patient had been exposed to anyone else with Covid-19, seven Coronavirus epidemiologic clusters in which presymptomatic transmission likely occurred were identified and 10 such cases within these clusters accounted for 6.4 % of the 157 locally acquired cases. In the four clusters for which the date of exposure could be determined, presymptomatic transmission occurred 1-3 days before symptom onset in the presymptomatic source patient, to account for the possibility of presymptomatic transmission, officials developing contact tracing protocols should strongly consider including a period before symptom onset, evidence of presymptomatic transmission of Covid-19 underscores the critical role social distancing, including avoidance of congregate settings, plays in controlling the Covid-19 pandemic.
According to the World Health Organization there is:
Symptomatic Transmission: Symptomatic of Covid-19 case who has developed signs and symptoms compatible with Covid-19 virus infection, symptomatic transmission refers to transmission from a person while they are experiencing symptoms, data from published epidemiology and virologic studies provide evidence that Covid-19 is primarily transmitted from symptomatic people to others who are in close contact through respiratory droplets, by direct contact with infected persons, or bu contact with contaminated objects and surfaces. This supported by detailed experiences shared by technical partners via WHO global expert networks and reports and presentations by Ministers of Health. Data from clinical and virologic studies that have collected repeated biological samples from confirmed patients provide evidence that shedding of the Covid-19 virus is highest in upper respiratory tract "nose and throat" early in the course of the disease, withing the first 3 days from onset of symptoms, preliminary data suggests that people may be more contagious around the time of symptom onset as compared to later on in the disease.
presymptomatic transmission: The incubation period for Covid-19, which is the time between exposure to the virus and symptom onset is on average 5 to 6 days, however can be up to 14 days, during this period also known as the presymptomatic period, some infected persons can be contagious, therefore transmission from a presymptomatic case can occur before symptom onset. In a small number of case reports and studies, presymptomatic transmission has been documented through contact tracing efforts and enhanced investigation of clusters of confirmed cases. This is supported by data suggesting that some people can test positive for Covid-19 from 1 to 3 days before they develop symptoms, it is possible that people infected with Covid-19 could transmit the virus before significant symptoms develop, it is important to recognize that presymptomatic transmission still requires the virus to be spread via infectious droplets or through touching contaminated surfaces.
Asymptomatic transmission: An asymptomatic laboratory confirmed case is a person infected with Covid-19 who does not develop symptoms, asymptomatic transmission refers to transmission of the virus from a person, who does not develop symptoms, there are few reports of laboratory confirmed who are truly asymptomatic and to date, there has been no documented asymptomatic transmission, this does not exclude the possibility that it may occur, asymptomatic cases have been reported as part of contact tracing efforts in some countries.
The World Health Organization regularly monitors all emerging evidence about this critical topic and will provide an update as more information becomes available. The researchers said in their findings that the possibility of presymptomatic transmission increases the challenges of Covid-19 containment measures, which are predicated on early detection and isolation of symptomatic persons and the magnitude of this impact is dependent upon the extent and duration of transmissibility while a patient is presymptomatic, which have not been clearly established.