Boston:
AIR Worldwide, the Boston-based catastrophe risk modeling firm, projected the number of severe cases of COVID-19 could range between 200,000 and 900,000 globally, with deaths ranging from 10,000 to 30,500, from now until April 1.During the same time period (March 18 to April 1), AIR said, the number of mild to moderately symptomatic cases globally could range between 600,000 and 2,000,000.
“Based on the estimations and projections from the AIR Pandemic Model, we estimate that this may represent a moderately conservative projection of cases; the vast majority will be asymptomatic or have mild symptoms,” said Dr. Narges Dorratoltaj, senior scientist at AIR Worldwide.
Dorratoltaj concluded, “There is high uncertainty around the fatality of the disease; however, it is estimated that COVID-19 has a higher case fatality rate (CFR) compared to seasonal flu (~0.1%) and a lower CFR compared to the 2003 SARS outbreak (~5.0%-10.0%). The current estimation for the average CFR ranges between 0.5% and 4%. According to the CCDC, among more than 72,000 patient records, with 86% of cases between 30 and 79 years old, current estimation for CFR ranges between 0.5% and 4%. CFR is estimated to be more than 5% for individuals with pre-existing conditions such as cardiovascular disease, diabetes, chronic respiratory conditions, hypertension, and cancer, and more than 8% for people older than 70 years old.”
Currently there is no specific treatment available for this disease other than supportive care. There are some antivirals and other treatments currently being used to treat patients. So far, fatality is most common in older patients, with more than 80% of deaths occurring in people over 60 years of age, more than 40% of whom have one or more pre-existing known co-morbidities, including cardiovascular disease, diabetes, and malignancies. It is also important to note that people who are more than 60 years old are generally at higher risk for any type of pneumonia and not just COVID-19 pneumonia. For these reasons, an overall increase in cases of the virus does not imply a commensurate increase in fatalities.
In countries with robust healthcare systems, any imported cases would most likely be contained with few or no transmissions to additional people—provided that cases are rapidly identified, and appropriate infection control protocols are followed. However, the current increase in the number of cases in some countries outside of China shows that there has been silent transmission that started in clusters and expanded to communities before health officials were able to contain them completely.
Dorratoltaj noted, “The difference between the low and high ends of the range is driven by a few factors. Uncertainty in the reported number of confirmed cases and the transmissibility of the virus play a significant role. Specifically, the lower end of the range represents a scenario where a) the true number of cases is relatively closer to what has been reported than estimated, and b) the possibility that containment measures (such as social distancing and quarantine) become more successful in reducing the transmission. If such containment measures—driven by international and/or local authorities—are successful, this could restrict the human-to-human transmission sufficiently to bring the eventual number of cases to or even below the low end of the modeled projected range of cases.”\
Current observations suggest that a high proportion of infected individuals with the novel coronavirus, COVID-19, develop very mild and nonspecific symptoms. Therefore, they may not seek medical care and may not be counted in the published figures. Moderately symptomatic individuals usually experience fever, fatigue, and dry cough, and may ask for medical care.
According to the China Center for Disease Control (CCDC), 81% of studied patients experienced mild to moderate symptoms and 14% of patients experienced severe symptoms; these severe symptoms include pneumonia, shortness of breath and, in more complicated cases, about 5% of patients according to CCDC, experienced acute respiratory distress syndrome, arrhythmia, and shock. A smaller percentage of patients also develop gastrointestinal (GI) symptoms, such as nausea and diarrhea. Intensive care unit (ICU) admission has been higher among people over 60 years of age with pre-existing comorbidities.