In the wake of the coronavirus (COVID-19) outbreak, multiple groups within the realm of healthcare research are working on strategies to stop/delay the spread of the infection. The two plausible strategies under consideration include both – the use of pharmaceutical interventions, and leveraging non-pharmaceutical interventions (NPI), such as short-term and long-term action plans to reduce mortality and human-to-human transmission of the disease.
1. Immunoprophylaxis (Vaccines)
Vaccines or antibody preparations can provide protection against viral infections. Active prophylaxis is the administration of a viral preparation, which could be a live attenuated virus or a killed virus or a recombinant vaccine, which, in turn, stimulates the body’s immune system to produce antibodies and activate T lymphocytes. An effective vaccine should protect over 90% of the population and produce a durable response. Meanwhile, passive prophylaxis is the administration of antibodies produced in another host that can impart protection to affected individuals. The long-term goal is to produce a vaccine that can be administered as a prophylactic measure to populations at large.
2. Antiviral and supportive therapy
This is a two-pronged approach and involves finding a medical entity that will inactivate the virus - thereby inhibiting its replication or maturation - and focusing on the use of immunomodulators that will boost the immune response of the host. The first direct approach inhibits viral propagation and can include shutting down the processes that help the virus infect individuals and subsequently replicate itself and infect surrounding cells. This can be achieved by targeting the key viral enzymes responsible for the process of binding to human cells and its replication. The second indirect approach is to boost the lung immune system through the administration of agents that will help reduce the pulmonary inflammatory response. The use of supportive care (oxygen cylinders and ventilators) and antibiotics to treat any secondary infections can also help reduce mortality.
3. Drug Repurposing
Developing a new vaccine requires one to identify the virus, sequence it, and produce the virus or the components required to elicit an immune response. However, testing the vaccine’s efficacy through clinical trials is a long-drawn process with no shortcuts. In the interim, a fast-track approach is to test existing drugs on infected individuals to boost their immune response and reduce the load of secondary infection. Repurposing existing antiviral drugs are the near-term treatment options. Additionally, the use of drugs that would reduce inflammation and boost immunity can be tried for symptomatic treatment. The World Health Organization (WHO) announced a major study, Solidarity, to compare treatment strategies in an international clinical trial where doctors from various countries can participate and contribute. Multiple potential COVID-19 treatments are being tested, including drugs already in use for HIV and malaria, experimental compounds that work against viruses in animal experiments, and antibody-rich plasma from people who have recovered from COVID-19.
Non-pharmaceutical interventions (NPIs)
The immediate line of action is to reduce the spread across the population and allocate healthcare resources efficiently. Epidemiological modelling that predicts the spread patterns of the disease can be established to assist informed policymaking until a viable vaccine is in place. Of utmost importance is the need to reduce contact rates and hence, reduce the transmission of the infection. Currently, there are two possible strategies:
The approach focuses on reducing the health impact of the epidemic – but not necessarily stopping the epidemic spread – by protecting those most at risk of severe infection. In this scenario, population immunity builds up through the epidemic, leading to an eventual decline in case numbers.
This aims to reduce the average number of secondary cases that each case generates or eliminate human-to-human transmission. The challenge here is to rely only on NPIs till such time that the virus is circulating in the population.
Making a choice between suppression and mitigation is not easy. Several factors, both scientific and economic must be taken into consideration. The suppression approach that might have worked with China and South Korea, comes with enormous social and economic costs, which, in turn, will impact health and well-being in the short and longer-term. Optimal mitigation policies can reduce peak healthcare demand by two-thirds and deaths by half. However, the mitigation approach results in a high mortality rate as at-risk groups cannot be completely protected, leaving the healthcare systems overwhelmed many times over.
Where do we stand?
Till the time a perfect solution is discovered, policymakers need to continuously analyse and evaluate all the possible strategies. By finding the right balance between pharmaceutical and non-pharmaceutical interventions, an actionable plan can be created to navigate these times.