LETTERS: Asymptomatic, symptomatic and pre-symptomatic transmissions are the three routes for Covid-19 transmission.
Pre-symptomatic transmission, however, seems more substantial than expected since the actual transmission intervals are shorter than the virus incubation period.
While the pathogenesis of SARS-CoV-2 is being unravelled, studies on other coronavirus family members (SARS-CoV and MERS-CoV) show that they have crown-like spike glycoproteins.
Thus, the viral entry into the host cells through the angiotensin-converting-enzyme-2 (ACE-2) receptors is caused by the receptor-binding domains on these spike glycoproteins, in the case of SARS-CoV-2.
Another target for SARS-CoV-2 attachment and subsequent entry into the host cell recently proposed is the extracellular matrix metalloproteinase inducer (EMMPRIN), otherwise known as BASIGIN/CD147.
The binding and attachment of the S-protein of SARS-CoV-2 with the host receptor ACE-2 initiates Covid-19 infection.
The ACE-2 receptors in humans' lower respiratory tract are mostly used by SARS-CoV to control human-to-human and cross-species transmission.
Covid-19 could be mild, ordinary, severe and critical, depending on its severity.
Signs and symptoms shown by patients include cough, fatigue, fever, sore throat, dyspnea (shortness of breath), septic shock, coagulation dysfunction, multiple organs failures, elevated levels of leukocytes, high plasma pro-inflammatory cytokines, refractory metabolic acidosis, anomalous respiratory manifestations and death.
With several cases of re-infection and the emergence of many variants (strains), the battle is yet to be over. At least 14 variants have been reported in Malaysia.
And with the nationwide third Movement Control Order from May 12 to June 7, there must be a change in attitude to stop this pandemic.
Everyone must respect and abide by the standard operating procedures and public health strategies, physical distancing, personal protective equipment (face masks, gloves and alcohol-based sanitiser), good hygiene, self-isolation, quarantine, active monitoring, contact tracing and surveillance.
Covid-19 patients are given broad-spectrum antibiotics, antiviral drugs, oxygen supplementation, and fluid balancing.
Old and new drugs are being used on an experimental basis in clinical trials.
Natural products and medicinal plants, whether alone or in combination with Western medicine, can be therapeutically effective as secondary interventions for the prevention and treatment of Covid-19.
The development of an effective therapeutic drug is important. Considering the multiple molecular signalling of action and replication of the Covid-19 virus, targeting multiple prospective targets seems reasonable.
The repurposing of drugs will also shorten the time of the drug discovery.
Since the binding of SARS-CoV-2 viral particles to the receptors of the host cell is the key to its spread and pathogenesis, it implies that the development of strategies to control or prevent the binding, thereby disabling the entry of the virus into the cells, could help to fight the disease.
All hands must be on deck. Let's play our roles without delegating our stewardship to others.
DR IDRIS ADEWALE AHMED
Visiting research fellow,
Centre for Natural Products Research and Drug Discovery (Cenar), Universiti Malaya
The views expressed in this article are the author's own and do not necessarily reflect those of the New Straits Times