What are the coronavirus vaccines effective against?

This is part 74 of our coronavirus FAQ. Click here to read other installments: #Coronavirus the facts. Find the latest information and answers from experts on everything COVID-19.

Why get vaccinated?

The expected benefits of vaccines are threefold: They help prevent infection, keep patients from developing symptoms or becoming severely ill, and they could help us reach herd immunity.

However, experts believe the vaccines for the new coronavirus do not offer complete protection against the virus. They help prevent people from developing symptoms or becoming seriously ill.

It is hard to ascertain how effectively they prevent infection because many people who become infected with the coronavirus remain asymptomatic. A detailed analysis of cells is also needed to determine if the virus has entered the human body.

The Pharmaceuticals and Medical Devices Agency (PMDA) evaluates drugs in Japan. According to the agency, when it comes to evaluating vaccines for the coronavirus, clinical studies are needed, in principle, to assess the vaccines' efficacy for preventing patients from developing symptoms.

Clinical tests in the US and Europe have shown their vaccines' effectiveness at preventing patients from developing symptoms and becoming seriously ill. Japan’s PMDA also includes the efficacy of preventing patients from becoming seriously ill as important criteria for evaluating coronavirus vaccines.

Another expected effect of coronavirus vaccination is herd immunity. The World Health Organization (WHO) estimates that over 70 percent of the population would need to be inoculated for the world to achieve that, and it believes it will be difficult to reach that by the end of this year.

How long are the vaccines effective?

It’s unclear, because clinical tests and actual vaccinations are still in the early stages.

Japan's health ministry says viruses, in general, mutate constantly, and minor mutations are unlikely to make the vaccines ineffective. The ministry says they will confirm the vaccines’ efficacy and safety, including their effectiveness against mutated strains.

The information is accurate as of February 26, 2021.