CoviD-19 symptoms and severity vary.
The disease may take a mild course with few or no symptoms as seen children – it may resemble other minor upper respiratory diseases such as the common cold. These mild cases typically recover within two weeks. The risk of death increases with age, for those less than 50 years the risk of death is 0.5% while those older than 70 it bumps up to more than 8 percent. Those with severe or critical cases may take three to six weeks before recovery. Among those who died of CoviD-19, the time from the onset of symptoms to death has ranged from two to eight weeks.
Note that it is not impossible for children to contract a severe form of the disease, most especially if they have an underlying co morbidity such as asthma.
There is currently no evidence that pregnant woman are at a higher risk for the disease. There is not yet a confirmed case of a pregnant woman transferring CoviD-19 to her infant and no confirmed case of CoviD-19 present in amniotic fluid or breast milk. It is paramount that nursing woman breastfeed their child without worry.
While this could be hopeful findings, pregnant woman should not be complacent as previous viruses similar to Sars CoV 2 (MERS and SARS) had the capacity to cause severe infection in pregnancy. While it this is not yet proven for CoviD-19, it must not be downplayed.
In some people, the disease affects the lungs causing pneumonia.
In the most severely affected, CoviD-19 may rapidly progress to ARDS or acute respiratory distress syndrome, causing respiratory failure, septic shock and / or multi organ failure.
Associated complications include sepsis, abnormal clotting, and damage to the heart, kidneys, and liver.
Many of those who died of CoviD-19 have pre-existing / underlying conditions, including hypertension, diabetes mellitus, and cardiovascular disease. According to one study the median time between onset of symptoms and death was ten days, with five days spent hospitalized. However, patients transferred to an ICU had a median time of seven days between hospitalization and death.
In a study of early cases, the median time from exhibiting initial symptoms to death was 14 days, with a full range of six to 41 days. In a study by the National Health Commission (NHC) of China, men had a death rate of 2.8% while women had a death rate of 1.7%.
Histopathological examinations of post-mortem lung samples show diffuse alveolar damage with cellular fibromyxoid exudates in both lungs. Viral cytopathic changes were observed in the pneumocytes. The lung picture resembled acute respiratory distress syndrome (ARDS). In 11.8% of the deaths reported by the National Health Commission of China, heart damage was noted by elevated levels of troponin or cardiac arrest.
Case Fatality Rate
In epidemiology, the case fatality rate (CFR) is the proportion of people who die from a specified disease among all individuals diagnosed with the disease over a certain period of time. It’s also used to evaluate effects of new treatments, with CFRs decreasing as treatments improve. CFR is not constant and varies overtime depending on the interplay between the causative agent of disease, the host, and the environment as well as available treatments and quality of patient care.
Presently, global mortality is reported at 4.7% but this varies widely by location from a high of 10.8% in Italy to a low of 0.7% in Germany. In contrast the Philippines CFR is presently given around 4%, implying about 4 deaths and 96 potential survivors per 100 cases.
It is good to take note that the availability of medical resources and socioeconomics of an area affect mortality. Estimates of the mortality vary because of these differences. Mild cases may have been under counted or left out which may cause the mortality rate to be overestimated, but the same can be said that previous deaths that were not confirmed were also left out causing the mortality rate to be underestimated.
Reinfection vs Long Term Immunity
It is currently unknown if past infection provides effective and long-term immunity in people who recover from the disease, hopefully it does.
Reports from China and Japan have indicated that some patients with COVID-19 who were discharged from the hospital after a negative RT-PCR result were readmitted and subsequently tested positive on RT-PCR. It is unclear from the available information if these were true reinfections or the tests were falsely negative at the time of initial discharge.
However, while other coronaviruses demonstrate evidence of reinfection, this usually does not happen for many months or years. Therefore, it is unlikely that these were true cases of reinfection.
Animal studies were more reassuring, as initial challenge and clearance of SARS-CoV-2, the animals (Rhesus Macaques) were re-challenged with the virus but were not infected.
Because the outbreak is only a few months old, there are no data on long-term immune response. Concerns have been raised about long-term sequelae of the disease. The Hong Kong Hospital Authority found a drop of 20% to 30% in lung capacity in some people who recovered from the disease, and lung scans suggested organ damage.
Main references: WHO, CDC, John Hopkin’s University, DOH.
- Cascella M, Rajnik M, Cuomo A, Dulebohn SC, Di Napoli R (2020). “Features, Evaluation and Treatment Coronavirus (COVID-19)”. StatPearls.
- Zhou F, Yu T, Du R, Fan G, Liu Y, Liu Z, et al. (2020). “Clinical course and risk factors for mortality of adult inpatients with COVID-19 in Wuhan, China: a retrospective cohort study”. The Lancet.
- Wang W, Tang J, Wei F (April 2020). “Updated understanding of the outbreak of 2019 novel coronavirus (2019-nCoV) in Wuhan, China”. Journal of Medical Virology.
- Zheng YY, Ma YT, Zhang JY, Xie X (March 2020). “COVID-19 and the cardiovascular system”. Nature Reviews. Cardiology
- Ji Y, Ma Z, Peppelenbosch MP, Pan Q (February 2020). “Potential association between COVID-19 mortality and health-care resource availability”. Lancet Global Health.
- Cheung E (13 March 2020). “Some recovered Covid-19 patients may have lung damage, doctors say”. South China Morning Post. Archived
- Case Fatality Rate
- Clinical Update of COVID-19 Pandemic, Omer et al April 6, 2020