Coronavirus vaccine latest: What is intranasal vaccine? How effective this can be

Coronavirus Covid-19 vaccine latest update: Researchers around the world have been trying to develop a vaccine that provides protection against the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). While the majority of the experimental Covid-19 vaccines are being tested in human trials through intramuscular injection, only a few have adopted the intranasal route for administering their Coronavirus vaccine candidates, as per data provided by the World Health Organisation.

However, on September 23, Hyderabad-headquartered Bharat Biotech, announced it would be manufacturing up to a billion doses of a single-dose intranasal coronavirus vaccine. This will be done in collaboration with the Washington University School of Medicine in St Louis, Missouri in the US. The coronavirus vaccine candidate is novel chimp-adenovirus based vaccine. Phase 1 human trials will take place in the US and further stages of the clinical trials are likely to be conducted in India depending upon the regulatory approval. Bharat Biotech is also working on India’s indigenous Coronavirus vaccine in collaboration with ICMR and NIV, Pune.

Inhaled versions of COVID-19 vaccine candidates developed by Oxford University-AstraZeneca and Imperial College would be trialed to see if they deliver a localized immune response in the respiratory tract, Reuters reported quoting British researchers. The Oxford-AstraZeneca and Imperial vaccines are both being tested in trials through intramuscular injection, but scientists from Imperial said that vaccines delivered via inhalation could potentially deliver a more specialized response. Chris Chiu, of Imperial’s Department of Infectious Disease, said there was evidence that flu vaccines delivered by nasal spray could protect against and reduce transmission of the disease. “We are keen to explore if this may also be the case for SARS-CoV-2 and whether delivering COVID-19 vaccines to the respiratory tract is safe and produces an effective immune response,” he said in a statement.

“We have already shown that (Oxford vaccine) ChAdOx1 nCoV-19 (AZD1222) is safe and induces strong immune responses after intramuscular injection,” said Leader of Oxford Vaccine team Sarah Gilbert. “Delivering the vaccine to the respiratory tract instead may be a good approach to inducing immune responses in the best place to enable a rapid response after exposure to airborne virus,” Gilbert said.

What is intranasal vaccine? Advantages, issues with intranasal vaccine

Intranasal vaccines are sprayed into the nostrils and inhaled. One of India’s leading vaccine scientists Dr Gagandeep Kang has termed the intranasal vaccine as an easy-to-deliver one. Virologist and Wellcome Trust DBT India Alliance CEO Dr Shahid Jameel said both intranasal and intramuscular vaccines tend to produce a response in the blood. However, vaccines administered through the nose or mouth have the capacity to tap into another set of immune cells found in mucosal tissues. The B cells that reside here can make another type of antibody, called IgA, that is very effective in destroying gut and airway pathogens. T cells in this tissue can create a memory and patrol the places they first encountered the pathogens, Jameel was quoted as saying by IE.

Apart from the impact, Intranasal vaccines are very useful in addressing the logistical challenge as well as cutting down the dependency on trained personnel to administer the vaccine, according to experts. The intranasal vaccine can be self-administered in pandemics and outbreaks, former CEO of Hilleman Laboratories Davinder Gill was quoted as saying by IE.

However, there have been very few pieces of evidence available to ascertain the efficacy of intranasal vaccines. Out of the 187 Covid-19 vaccine candidates officially listed by WHO as experimental COVID19 vaccine candidates, only five vaccine candidates have been specifically listed so far as working on the intranasal route of delivery. Apart from some flu vaccines, other trials to deliver through the nasal route have remained unsuccessful, according to experts. Dr Kang has also pointed out the dosage issues as there is uncertainty regarding what dosage can be administered with a spray versus an injection. Dr. Jameel said that around 0.1 ml can be administered in each nostril through the intranasal route. Dr. Jameel said that the vaccine antigens must be produced in high concentration and proper delivery vehicles for either single or multiple-use have to be developed and these present the most significant challenge, as per IE report.