CoV behaves like SARS, has its origin from bats, spreads like large droplets and from people having lower respiratory infections AND so preventable to an extant

It’s official: CoV behaves like SARS, has its origin from bats, spreads like large droplets and from people having lower respiratory infections AND so preventable to an extant

Dr KK Aggarwal

President CMAAO, HCFI and past National President IMA

Every decade a zoonotic coronavirus crosses species to infect human populations and in this decade we have a virus, provisionally called 2019-nCoV, first identified in Wuhan, China, in persons exposed to a seafood or wet market.

In earlier two decades we had outbreaks caused by two other pathogenic human respiratory coronaviruses (severe acute respiratory syndrome coronavirus [SARS-CoV] and Middle East respiratory syndrome coronavirus [MERS-CoV]), causing respiratory disease that is often severe. In the current situation the mortality rate is  3%.

Scientists have identified and characterized 2019-nCoV. The viral genome has been sequenced. The virus is 75 to 80% identical to the SARS-CoV and even more closely related to several bat coronaviruses.

It can be propagated in the same cells that are useful for growing SARS-CoV and MERS-CoV, but notably, 2019-nCoV grows better in primary human airway epithelial cells than in standard tissue-culture cells, unlike SARS-CoV or MERS-CoV.

Both SARS-CoV and MERS-CoV infect intrapulmonary epithelial cells more than cells of the upper airways. Consequently, transmission occurs primarily from patients with recognized illness and not from patients with mild, nonspecific signs. It appears that 2019-nCoV uses the same cellular receptor as SARS-CoV (human angiotensin-converting enzyme 2 [hACE2]), so transmission is expected only after signs of lower respiratory tract disease develop.

It is likely that 2019-nCoV will behave more like SARS-CoV.

Given its close similarity to bat coronaviruses, it is likely that bats are the primary reservoir for the virus. SARS-CoV was transmitted to humans from exotic animals in wet markets, whereas MERS-CoV is transmitted from camels to humans. In both cases, the ancestral hosts were probably bats.

Transmission of 2019-nCoV probably occurs by means of large droplets and contact and less so by means of aerosols and fomites, on the basis of our experience with SARS-CoV and MERS-CoV.

Public health measures, including quarantining in the community as well as timely diagnosis and strict adherence to universal precautions in health care settings, were critical in controlling SARS and MERS.  [ Excerpts from NEJM]