Nose sprays, needle-free patches, durable immunity: A look at the next generation of Covid-19 vaccines

Nose sprays, needle-free patches, durable immunity: A look at the next generation of Covid-19 vaccines

By Kylie Quinn

The past 20 months has seen an explosion of vaccine development, with Covid-19 vaccine testing and rollout happening at an unprecedented pace in the face of a global pandemic.

There have been absolute triumphs – the fact we have multiple safe, effective vaccines is remarkable – but there have also been challenges.

We’ve seen storage and delivery issues, vaccine hesitancy, breakthrough infections and the beginnings of waning immunity.

Vaccine innovators around the world have these challenges in their sights. They are already working on the next generation of Covid vaccines.

Tweaking current vaccines

After hundreds of millions of doses, we have a good handle on how current vaccines are performing and where they can be improved. As more data is gathered, a modified dose, time between doses, and/or using different vaccines together in mix-and-match strategies may become the preferred approach.

We could also improve vaccines that aren’t performing at their best.

Inactivated vaccines have been used in many parts of the world but their early protection has waned, particularly in older people, with the World Health Organization now recommending a third dose.

One way to improve this could be to add an adjuvant – something that fires up the immune system. One such vaccine, called Valneva, has early results that suggest including an adjuvant improves immunity.

Making vaccination easier

As we have seen, vaccinating large numbers of people is not easy. Innovations to make this easier will be welcome.

Needle-free approaches would be ideal. One approach, known as a nanopatch vaccine, coats the vaccine onto tiny spikes on a small patch.

The patch is applied to the skin and the spikes deliver the vaccine to a dense barrier of immune cells sitting just under the top layers of our skin. A nanopatch Covid vaccine developed by Vaxxas and researchers in Queensland has been shown to trigger strong immune responses in animal models, with trials underway in humans.

Another approach, known as an intranasal vaccine, sprays a vaccine up the nose. This would be easier to deliver and it could also build immunity in the right location in our body.

The coronavirus infects us through the lining of the nose, mouth, throat and lungs – a type of sticky tissue that lines body cavities and some organs called mucosa.

Currently, Covid vaccines are delivered into our arm muscle and build antibody levels in our blood and tissue, with some antibody spilling out into the mucosa. Delivering the vaccine directly to the mucosa might be a better approach for preventing Covid infection. This is being trialled with a number of vaccines, including the AstraZeneca vaccine.

If yearly Covid boosters are recommended for some or even all of the population, it would be easier to deliver them together with the yearly flu vaccine. These “multipathogen” vaccines are being tested with current flu vaccine or even new types of flu vaccine.

More durable immunity

With two doses of the current vaccines, immunity is seen to decline and poor responses are seen in certain groups such as the severely immune-compromised and older people. Covid vaccines that can induce more durable immunity, more consistently across vulnerable populations would be a major innovation.

This could require completely new vaccines. Protein subunit vaccines – which use purified protein from the surface of the virus as a target – are still working their way through approvals around the world.

One example is the Novavax vaccine, but there are a large number of other protein subunit vaccines also development that often use new adjuvants – again, the vaccine ingredient that fires up your immune system. These new adjuvants could support more durable immunity but this remains to be tested.

The Conversation