In December 2019, a number of pneumonia cases with an unknown etiology were first reported in Wuhan city, Hubei Province, China. A previously unknown coronavirus was later identified and the disease was initially named to represent this – 2019 novel coronavirus (2019-nCoV).
The outbreak was declared a Public Health Emergency of International Concern on 30th January 2020. On 11th February, the WHO officially named the disease ‘coronavirus 2019 (COVID-19)’ and the virus responsible ‘severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)’ due to its genetic similarity to the virus that caused the 2002–2004 SARS outbreak. The COVID-19 outbreak was officially acknowledged as a pandemic by the WHO on 12th March 2020.
What are coronaviruses?
Coronaviruses are named for the crown-like spikes of protein complexes that are scattered on their surfaces. They are a large family of viruses that were originally associated with mild illnesses such as the common cold.
Coronaviruses are zoonotic, which means they are able to transmit between animals and humans. Transmissions to humans are usually from other mammals such as bats, via an intermediate host.
Over the past two decades we have seen examples of coronaviruses originating in bats such as severe acute respiratory syndrome coronavirus (SARS-CoV) in 2002 and the Middle East respiratory syndrome coronavirus (MERS-CoV) in 2012, in which the intermediate hosts were civet cats and dromedary camels, respectively.
Since the first reported case, COVID-19 has spread to many countries across the globe. While originally transmitted from animals to people, person-to-person spread then occurred and community spread is now widespread.
This spread is usually through respiratory droplets – similar to influenza. This occurs when someone with the virus coughs or sneezes in close proximity to other people (less than six feet away), and it makes contact with their mucous membranes. Additionally, it is thought that the virus can spread through touching an object/surface with the virus on it, and then touching your eyes, nose, or mouth.
COVID-19 can cause respiratory illness; however, the complete clinical picture is not yet fully known. The incubation period is currently thought to be within 14 days of exposure, with symptoms appearing between 2 and 14 days, and these include:
- Shortness of breath
Reported illnesses range from very mild (including some asymptomatic cases) to severe. In severe cases, infection can result in pneumonia, severe acute respiratory syndrome (SARS), and even death.
Individuals of any age can acquire SARS-CoV-2 infection, although to date adults of middle age and older have been most commonly affected. Furthermore, limited cases have been noted in individuals younger than 20.
Some groups are at greater risk of developing more serious COVID-19 illnesses. These include older adults and people of all ages who have underlying health conditions, such as heart disease, lung disease, and diabetes.
At time of writing, diagnosis has involved presentation with the above symptoms, in addition to:
- Known close contact with a confirmed or suspected case of COVID-19
- Residing in, or travelling to, areas where widespread community transmission has been reported
- Attending an event, or spending time, in an area where COVID-19 cases have been reported
Infection is then confirmed by collection of an upper respiratory tract sample and a sputum sample from the lower respiratory tract if possible. A polymerase chain reaction test is used to detect and confirm the presence of SARS-CoV-2 in the sample.
Other tests such as a white blood cell count and a chest CT scan can be undertaken. While not definitive, they can help in the diagnosis of suspected cases of COVID-19.
A range of investigational agents are being explored for COVID-19, with many clinical trials ongoing or pending. These cover investigational products such as vaccines, antibodies, and small molecules, and investigational products with a range of mechanisms of action, including blocking virus entry to cells, delaying the immune response, and blocking viral replication.
Currently, one of the more promising candidates is Remdesivir – a novel nucleotide analogue that has broad-spectrum antiviral properties. It has shown promising data in both in vitro and animal model studies against coronaviruses, and clinical trials in humans are now underway. Successful use of Remdesivir has been reported in the United States, where one patient was cured of COVID-19 symptoms after treatment with it.
The combined protease inhibitor lopinavir-ritonavir, which is used in HIV patients, has also attracted interest. It has shown positive results against SARS-CoV in vitro and MERS-CoV in animal studies, and its use has been described in some COVID-19 cases. Trials of lopinavir-ritonavir are underway, both studying its use in combination with other investigational compounds and its use as a monotherapy.
The National Institute of Allergy and Infectious Diseases (NIAID) Vaccine Research Centre is utilizing knowledge from a network of collaborators across academia, government, and industry to develop a vaccine. One approach is based on a candidate (mRNA-1273) that expresses the viral spike protein of SARS-CoV-2 using messenger RNA vaccine technology. This is currently undergoing Phase 1 trials in healthy adults (NCT04283461).
Since the first reports of COVID-19 in December 2019, the infection has spread worldwide at an alarming rate. Emphasis has been placed on the detection of cases, prevention of spread, and protection of healthcare facilities where possible.
While research efforts are underway, it is unclear if and when a successful treatment for COVID-19 will be reached. Until then, management of those who have the disease is currently based on severity, with milder cases advised to isolate at home, and those with more severe illness prioritized for hospital care.