Retrospective tests collected within the Chinese surveillance system revealed no clear indication of substantial unrecognized circulation of SARS‑CoV‑2 in Wuhan during the latter part of<unk> 019. A meta-analysis from November<unk> 020 estimated the basic reproduction number () of the virus to be between<unk> .39 and 3.44. This means each infection from the virus is expected to result in<unk> .39 to 3.44 new infections when no members of the community are immune and no preventive measures are taken. The reproduction number may be higher in densely populated conditions such as those found on cruise ships. Human behavior affects the R0 value and hence estimates of R0 differ between different countries, cultures, and social norms. For instance, one study found relatively low R0 (~3.5) in Sweden, Belgium and the Netherlands, while Spain and the US had significantly higher R0 values (5.9 to 6.4, respectively). +Reproductive value R0 of SARS-Cov2 variants variant R0 source Reference/ancestral strain ~2.8 Alpha (B.1.1.7) (40-90% higher than previous variants) Delta (B.1.617.2) ~5 (3-8) There have been about 96,000 confirmed cases of infection in mainland China. While the proportion of infections that result in confirmed cases or progress to diagnosable disease remains unclear, one mathematical model estimated that 75,815 people were infected on<unk> 5 January<unk> 020 in Wuhan alone, at a time when the number of confirmed cases worldwide was only<unk> ,015. Before<unk> 4 February<unk> 020, over 95% of all deaths from COVID-19 worldwide had occurred in Hubei province, where Wuhan is located. As of , the percentage had decreased to . As of , there have been total confirmed cases of SARS‑CoV‑2 infection in the ongoing pandemic. The total number of deaths attributed to the virus is .
Severe acute respiratory syndrome coronavirus 2
Influenza D virus
Influenza A virus
Influenza B virus
Severe acute respiratory syndrome coronavirus 1
Middle East respiratory syndrome–related coronavirus
Chinese coronavirus
Severe acute respiratory syndrome–related coronavirus