Can we switch COVID-19 vaccine shots with pills? Researchers in Japan claim they have developed new methods to administer fast-acting COVID-19 vaccines orally.

According to a study, published in the journal Biology Methods and Protocol, scientists from Japan's Intelligence and Technology Lab tested the vaccine pill on monkeys, and the drug produced the necessary antibodies against the disease without any visible side effects.

The pill, designed for under-the-tongue administration, is very much like the vaccine shot, as it contains a non-active portion of the virus. However, unlike the vaccine, the pill releases the inactivated virus into the mucus and helps to elicit a faster response in tackling the actual virus before it infects the body.

"The best way to neutralize viruses is before they can enter inside human cells but are only on the external surface of epithelial cells that line and produce mucus in the lungs, nose and mouth. A specific class of antibodies, known as Immunoglobulin A, operates in mucus and can disable viruses. However, production of specific immunoglobulins/antibodies for a given virus has to be first induced by vaccination," researchers said in a news release.

Since the coronavirus primarily affects bronchial cells just like a flu virus, researchers aimed to trigger the production of virus antigen-specific Immunoglobulin A in the mucosal lining rather than in the bloodstream.

Scientists had earlier developed nasal or oral vaccines, and they were found to be more effective in inducing Immunoglobulins A than the subcutaneous vaccines. However, these vaccines had side effects such as headaches and fever and impacted the central nervous system or lungs.

Researchers hope that after further research and clinical trials, the new drug can be used as an effective preventive strategy against the coronavirus.

The U.S. Food and Drug Administration (FDA) and the Centers for Disease Control and Prevention (CDC) approved updated COVID-19 shots from Pfizer and Moderna earlier this week. The vaccines are expected to be available for public use by the end of this week.

The CDC recommends all people aged six months and older should receive the updated COVID booster. As COVID cases spike, health officials hope the updated vaccines that target omicron subvariants circulating throughout the country will help boost people's waning immunity.