If Covid-19 vaccines are the superheroes, fighting against the worst effects of coronavirus with a needle and vial, they’re soon set to get a seriously kick-ass sidekick in different guise: the nasal spray.

Teams of scientists around the world are hard at work developing sprays that will not only deliver Covid-19 vaccines into the body – great news for needle phobics – but may also help prevent and treat early infection from the virus.

The nose, you see, is a key entry point for the SARs-CoV-2 virus. It gets in via the droplets produced when someone infected with Covid-19 coughs, sneezes or speaks. Cells inside the nose have more of a certain receptor – the ACE-2 receptor – than other cells in the body, and these are like magnets for the coronavirus, making the nose far more susceptible to the unwanted invader.

There, the virus can lock on to and enter cells using its spike protein – and rapidly multiply. This is why it’s so important to wear a face mask over your nose as well as mouth – but it’s also where nasal spray vaccines come in…

Since the nose is a key route for the virus to infiltrate the body, targeting it could not only help prevent people from getting the virus, but also offer an early form of treatment, effectively stopping the virus in its tracks before it travels further into the body and wreaks more havoc.

One such spray, called Taffix, has already been found to prevent Covid-19 from occurring. A trial among Orthodox Jews attending a religious festival in Israel in September 2020 found that while the celebration was effectively a super-spreader event – with infections in the local population rising from 18% to 28% – a small group of people didn’t seem to be impacted much. 

The reason? They used a nasal spray. Of 243 participants, 83 used the Taffix spray during the two-day event and for the following two weeks. The spray is thought to work in 50 seconds and offers protection for up to five hours.

When rates of infection were examined, two participants in the nasal spray group tested positive for Covid-19 compared to 16 in the group who declined the product. This equated to a 78% reduction in risk of infection when the spray was used.

The spray wouldn’t be a replacement for face masks, warn its creators – rather an additional layer of protection. Dr Dalia Meggido, co-founder and chief executive officer of Nasus Pharma, the biopharma company that developed the spray, said it could be particularly useful in high-risk settings such as on public transport and in shops and schools.

The Lancaster team hopes to make its nasal spray vaccine suitable for children. “We already have the success story of the influenza vaccine being given to children through the nose so we are confident our approach will work,” virologist and project lead, Dr Muhammad Munir, previously told HuffPost UK.

Australian biotech company, Ena Respiratory, has also been working on a nasal spray that aims to help prevent Covid-19 – by boosting the immune system. It works by stimulating the innate immune system, the first line of defence against the invasion of pathogens into the body.

When taken once or twice weekly, this nasal spray reduced viral replication of SARS-CoV-2 by up to 96% in ferrets. By boosting the immune response at the primary site of infection, the ability of the Covid-19 virus to infect and replicate was dramatically reduced, a study by Public Health England showed.

While nasal sprays are proving to be useful in preventing the virus from entering the body’s cells, some are being developed which could also act as treatments for early infection. One Canadian nasal spray is being tested as a treatment for the virus in clinical trials at Ashford and St Peter’s Hospitals NHS Foundation Trust in Surrey. The nitric oxide nasal spray – called SaNOtize – is designed to kill the SARS-CoV-2 virus in the upper airways and stop it from replicating and spreading to the lungs.

In lab tests, the spray proved to be 99.9% effective in killing the virus within two minutes, and in animal tests, rodents who were given the spray and deliberately infected with the virus saw a 95% drop in viral load within a day of infection, while others showed no detectable virus. Nitric oxide – the spray’s key active ingredient– has been shown to block the ACE-2 receptor which is essential for the virus to infect our cells. 

Rob Wilson, a former British government minister who represents SaNOtize in the UK and EU, said that if the trials were successful, we could have “an effective, safe and accessible treatment within months” that people can use daily to kill the coronavirus and stop it spreading.