Scientific research about Covid-19 continues to evolve even as the novel coronavirus itself has mutated into the highly transmissible Delta variant that has caused a renewed surge in infections in countries from the UK and the US to those in Africa and Asia. Delta is one of four ‘variants of concern’ listed by the World Health Organisation. Such variants are deemed to be more contagious, more resistant to current vaccines and treatments, or could cause more severe illness. The Delta variant has become the dominant strain causing Covid-19 in many countries.
As things stand now, vaccination is considered the most effective measure against the pandemic that has turned life upside down since it originated in the Chinese city of Wuhan in December 2019. It is in this context that a latest development from the University of Lancaster, UK, offers more hope. Scientists have developed a Covid-19 vaccine that can be delivered via a nasal spray. In a preclinical trial, the vaccine was found to decrease both disease severity and transmission of the virus. The study results are published in the journal iScience. All the other vaccines, authorised for human use against Covid-19 are administered via intramuscular injection and have proven highly effective in reducing the risk of severe Covid-19 and death, saving many lives across the globe.
But, intranasal vaccines are an example of an alternative approach for vaccination. Researchers at the University of Lancaster have been working in collaboration with scientists at the Texas Biomedical Research Institute to develop in this regard. Intranasal vaccines offer several advantages over the currently authorised vaccines, including the potential to block viral transmission. Scientists are of the view that the next generation of Covid-19 vaccines must be able to stop transmission of the virus in individuals that have already been vaccinated. The intranasal vaccine essentially nips the novel coronavirus, which causes Covid-19, in the bud. The concept is to eliminate the virus before it infects the cells that line our respiratory system, where it produces millions of progeny and triggers a cascade of replication. This process takes place in a very short time frame, and once the infection spreads, it’s hard to get under control. Through the intranasal vaccine scientists are looking to can train the cells that line our respiratory system against the virus, so that they will be better equipped to tackle the virus before it starts its infection.
The intranasal vaccine developed at the University of Lancaster is based on a bird virus known as Newcastle disease virus (NDV), which is harmless to humans. The researchers took a severe acute respiratory syndrome coronavirus 2 (Sars-CoV-2) antigen and incorporated it into a NDV such that it acts as a surrogate and presents the antigen to our immune cells. Since the NDV is harmless to us, it provides a mirror image of Sars-CoV-2 and trains our immune system to fight the virus if an individual gets exposed to Sars-CoV-2. The intranasal vaccine in pre-clinical studies produced antibodies that can neutralise several important variants in laboratory experimentation. Given the nature of the vaccine and technology involved, the scientists expect the induction of immunity against current or future variants.
A unique feature of the intranasal vaccine is its economical and sufficient production in chicken eggs, adopting the same infrastructure used to produce influenza vaccines. In terms of the next steps, the vaccine is heading for human clinical trials.
