Two inhaled covid vaccines have been approved—but we don’t know yet how good they are

In the last week, regulatory bodies in both India and China have approved inhaled vaccines for covid-19. These vaccines are claimed to boost immunity in people who have been vaccinated. Here’s what we know sofar.

What are the new vaccines for?

On Sunday, CanSinoBIO, a biopharmaceutical company based in Tianjin, China, announced that its inhaled vaccine, called Convidecia Air, had been approved as a booster by the National Medical Products Administration of China. The vaccine is inhaled through the mouth, and the company says it can “effectively induce comprehensive immune protection in response to Sars-CoV-2 [the virus that causes covid-19] after just one breath.”

The approval was swiftly followed by that of another inhaled vaccine, developed in India. Bharat Biotech, based Hyderabad , announced Tuesday that its nasal vaccine, iNCOVACC, was approved for “restricted usage in emergency situations” in that country as a booster dose for those who have had two doses.

How does it work?

Both vaccines promise to induce an immune response within the linings the airways, something immunologists call mucosal immunity. Once antibodies are present, they should be able provide a faster response to any virus entering the body through the nose or mouth. This immunity could in theory prevent someone from getting infected and potentially prevent them from passing it on to others. “They’re sitting right where the virus is going be encountered, which means that they can act very quickly,” Ed Lavelle, an immunologist from Trinity College Dublin, Ireland, says.

Do we really need more covid-19 vaccines?

We could do with better ways to protect ourselves from covid-19. While the number of covid-19 cases continues to decline–globally, weekly cases have fallen by around 12% in the last week–the virus is still responsible for many deaths. Last week, a person died from covid-19 every 44 seconds, Tedros Adhanom Ghebreyesus, director general of the World Health Organization, told journalists at a press briefing on Wednesday. He stated that most of these deaths could have been avoided.

Will inhaled vaccines be replaced by injected ones?

No. Injected vaccines can cause antibodies to be produced in the bloodstream and in the internal organs of a person, which in turn provide strong immunity to any invading viruses. Lavelle believes that both vaccines will work well together.

Research in animals suggests that an injected vaccination followed by an inhaled one can provide the best defense against infection, in what’s known as a “prime-pull” technique. Inhaled vaccines can boost the immune system while the injected ones prime it. Lavelle emphasizes that it is not yet clear if this approach will work in humans.

Which one of the inhaled vaccines is better?

We don’t know yet. Both vaccines are administered through the nose and mouth differently. It is not clear which route is best. In theory, either route of vaccination should trigger immunity in the nose and mouth, as well as the upper airways, including lungs. Lavelle says that protection will be strongest regardless of where the vaccine is given.

Can inhaled vaccines be used to end the pandemic? This is the big question and, unsurprisingly, there’s no easy answer. In theory, if the vaccines can help prevent infections and transmission, they could have a huge impact on covid-19.

But there’s a lot we don’t know. We don’t know how many vaccines offer protection. The level of protection will vary depending on the type of vaccine given. Lavelle says, “It depends upon the duration of the immune response [in the body] as well as how much the virus is changing over that time.”

We haven’t seen all of the data on how effective the inhaled vaccines were.

Representatives from the World Health Organization agree with him. Nasal vaccines could boost a person’s “first line of defense” against the virus behind covid-19 and have the potential to reduce onward transmission, Mike Ryan, executive director, WHO Health Emergencies Programme, told journalists at a press briefing on Wednesday. “But it remains to be seen.”