Likewise, the average time from symptom onset to recovery is two weeks when the disease has been mild and between three and six weeks when it has been severe or critical. Similarly, the time between the onset of symptoms until the onset of severe symptoms such as hypoxemia is one week.
Regarding the incubation period, the document confirms that the median incubation period is 5-6 days, with a range of 1-14 days. Furthermore, 97.5 percent of symptomatic cases develop within 11.5 days after exposure.
The average serial interval in numerous epidemiological observations has been less than the incubation period, therefore, based on these observations and the cases detected in the exhaustive contact studies, it is considered that transmission of the infection begins one or two days before the onset of symptoms.
In this sense, Health reports that currently it is unknown whether the intensity of transmission from asymptomatic persons It will be the same as from people with symptoms, although the viral load detected in one asymptomatic case is similar to that of other symptomatic cases, an effect that has also been observed in an animal model.
Specifically, in mathematical models based on the outbreaks of Singapore and Tiajin (China), transmission rates have been estimated from presymptomatic cases of 45 percent and 62 percent, respectively.
The transmission route between humans is considered similar to that described for other coronaviruses through the secretions of infected people, mainly by direct contact with respiratory drops of more than five microns (capable of being transmitted over distances of up to two meters) and the hands or fomites contaminated with these secretions followed by contact with the mucosa of the mouth, nose or eyes.
Likewise, Health indicates that the new coronavirus has been detected in nasopharyngeal secretions, including saliva. At the same time, he comments that although the genome and infective virus have been detected in the faeces of sick people, transmission through the faeces is another hypothesis for which there is no evidence in this epidemic to date.
“The gastrointestinal clinical manifestations, although present are not too frequent in the cases of Covid-19, which would indicate that this transmission route, if it existed, would have a minor impact on the evolution of the epidemic“the Ministry reports in the document.
About the symptoms, the data obtained for now in Spain show that with 18,609 reported cases, the most frequent symptoms were fever or recent history of fever (68.7%), cough (68.1%), sore throat (24.1%), dyspnea (31%), chills (27%), vomiting (6%), diarrhea (14%) and other respiratory symptoms (4.5%).
Also, in investigations carried out in Wuhan (China), other symptoms related to different organs and systems have been described, for example, neurological, cardiological, ophthalmological, otorhinolaryngologists, dermatological and hematological.
The presence of comorbidities ranges from 23.2 percent to 51 percent, with cardiovascular disease (particularly high blood pressure) and diabetes being the most frequent among hospitalized patients, although these series include cases of different severity and not they are clearly interpretable.
In the cases of deaths from Covid-19, it is also observed increased prevalence of cancer or neurological diseases compared to population-based and non-severe cases, although the effect is less evident than in the previously described diseases.
Refering to high blood pressure, liver disease and immunosuppression there does not seem to be an important association with Covid-19, according to the available data, although in other series, arterial hypertension has been recognized as one of the most important factors associated with the poor evolution of the disease.