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.
AIR’s model-based estimates account for uncertainty and underreporting. Mild to moderate symptoms are the types of cases least likely to be captured in the official numbers, but even for severe cases and deaths, it is likely that there will be significant underreporting, said AIR.
The difference between the low and high ends of the ranges for numbers of cases is driven by a few factors such as uncertainty in the reported number of confirmed cases and the transmissibility of the virus, noted Dorratoltaj.
She said 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) are 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,” she added.
“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%),” said Dorratoltaj.
“The current estimation for the average CFR ranges between 0.5% and 4%,” she said.
According to the China Center for Disease Control’s (CCDC) analysis of more than 72,000 patient records, the current estimate of CFR ranges between 0.5% and 4% in 86% of cases aged between 30 to 79 years, explained Dorratoltaj. “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.”
AIR went on to discuss the following facts/statistics related to the coronavirus outbreak:
- The country most affected by the outbreak has been China, which has reported 82,007 cases and 3,338 deaths. China has also reported that the number of new cases there has continued to decline due to early and aggressive containment measures.
- Outside China, a total of 102,968 cases of COVID-19 have been reported, with 4,191 deaths.
- South Korea has reported 8,320 cases and 81 deaths with a decline of new cases reported.
- The largest outbreak is currently in Italy with 27,980 cases and 2,158 deaths, followed by Iran with 16,169 cases and 988 deaths, and Spain with 11,178 cases and 491 deaths.
- On Friday, March 13, the WHO stated that Europe had become the epicenter of the pandemic, with the majority of new cases coming from this region, outpacing China.
- Case numbers are growing in the United States as testing is expanding, with 3,536 confirmed cases and 58 deaths from the disease. New York, Washington, California, and Massachusetts have reported the highest case numbers.
- This is the first pandemic caused by a coronavirus, according to the World Health Organization (WHO).
AIR noted that the virus responds well to comprehensive containment measures, such as those used in China and South Korea.
On the treatment front, said AIR, several countries have reported a shortage of ventilators for those in danger of lung failure—a major cause of death from this disease—and they are attempting to acquire more. In addition, the modeling firm said, some antivirals originally developed against other viral infections such as Ebola or HIV, are being re-purposed and tested in COVID-19 clinical trials.
Researchers and scientists across the world are working to develop treatment and a vaccine for COVID-19, said AIR, noting that during the week of March 16, a clinical trial to test a vaccine got underway, but a successful vaccine will not be available for a year or more.
Currently there is no specific treatment available for this disease other than supportive care, although there are some antivirals and other treatments currently being used to treat patients, said AIR.
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, explained AIR.
“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,” the modeling company continued.
Current observations suggest that a high proportion of infected individuals with the novel coronavirus, COVID-19, develop very mild and nonspecific symptoms, said AIR. Therefore, they may not seek medical care and may not be counted in the published figures. However, 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, while in more complicated cases, about 5% of patients experienced acute respiratory distress syndrome, arrhythmia and shock, said AIR quoting the CCDC.
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 co-morbidities.
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, said AIR.
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, the company concluded.
Source: AIR Worldwide
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