World Health Organization (WHO)  declared the 2019 novel coronavirus on 31 December 2019 as a new and emerging disease following a report of cluster of pneumonia cases in Wuhan, China. The clinical spectrum of COVID–19 has varied on the degree of severity[3, 4]. In mild cases, patients have presented with non-pneumonia or mild pneumonic symptoms such as fever, malaise and dry cough. However, 14% of severe cases, patients present have presented with dyspnea, respiratory frequency of is more than 30/min and blood oxygen saturation (SpO2) of below 93%. Patients who were at a critical stage (occurring in 5% of cases) may experience septic shock, respiratory failure, and multiple organ failure. COVID–19 is presumed to have originated from be animal-to-human transmission. Human-to-human transmission now occurs occur through respiratory droplets via coughing and, sneezing or coming in contacts with contaminated surfaces.
The first COVID–19 related death was confirmed on 9 January 2020 in China. The first case outside China was confirmed in Thailand on 13 January 2020. As of 28 March 2020, 3:30 PM (UTC+10:30 Adelaide time), there were 597,304 confirmed cases over 176 countries with the top ten hardest hit countries including the United States of America (104,661), Italy (86,498), China (81,946), Spain (65,719), Germany (50,871), France (33,414), Iran (32,332), the United Kingdom (14,751), Switzerland (12,928) and South Korea (9,478). To date (28 March 2020), there have been over 27,364 deaths and the following countries had the highest number of death records: Italy (9,134), Spain (5,138), China (3,296), Iran (2,378), France (1,995), The United States of America (1,296), United Kingdom (759), Netherland (546), Germany (351) and Belgium (289). WHO reports that the global case fatality rate as of 23 March 2020 was 4.4%, ranging up to 7.2% in Italy.
The WHO declared COVID–19 as Public Health Emergency of International Concern (PHEIC) on 30 January 2019 and a as a pandemic on 11 March 2020. In its short life, of less than two months, this pandemic has swiftly caused significant socio-economic, cultural and political crisis across the world. A number of countries have declared a state of emergency which has led to many changes globally, including cancellation of international and domestic flights, curtailing of essential travel by closing international and state borders between and within countries, closing public spaces and events and changing the way businesses are operated such as universities changing teaching modalities and teaching virtually. These abrupt changes have led to significant impacts on communities and individuals such unemployment, loss of social network and social capital.
Given the disease is now spread to 176 countries, evidence from available data provides a differing picture about the natural history and spectrum of the disease i.e. incubation period, infectivity, pathogenicity and virulence, and basic reproduction number. For example, the China Center for Disease Control and Prevention (CDC) and local CDCs, using data from the first cases in Wuhan, reported a 3–7 days of incubation time, 9.2 to 18 days of infectious period, and 2.2 basic reproduction number (R0). Furthermore, the incidence, prevalence and mortality rates vary from country to country. For example, while Europe is becoming the hotline,Africa is the least affected at this stage.
Obtaining exact data for these important variables is significant in mapping the number and speed of transmission. As the virus does not have a specific treatment, the only viable solution is halting the transmission through isolation or quarantine. Furthermore, having correct data is important to drive the implementation of new of mitigation strategies. For example, some countries have ordered a complete lockdown, others are allowing essential daily business and planning to adapt a ‘new normal’, and some are still conducting routine activities normally. We therefore need to have a pooled data of these variables to build evidence that will inform effective and seamless contextual policies and practices.
The aim of the present study is to synthesize and (pool using meta-analysis) global data of incidence and basic reproduction number of COVID–19. We will also synthesize evidence on the incubation period, infection time and mortality rates of COVID–19.