Moderna Says Its COVID-19 Vaccine Should Provide Immunity for at Least 1 Year

Immunity from Moderna’s COVID-19 vaccine should last for at least a year, the company told investors at the J.P. Morgan Healthcare conference on Monday.

The Moderna mRNA vaccine is one of two COVID-19 vaccines authorized for emergency use in the U.S. Clinical trials indicate that the vaccine is 94% effective at protecting against the virus. However, there is no definitive data yet on how long immunity will last.

To achieve maximum immunity, a person must receive two doses of the vaccine, spaced 28 days apart. Tal Zaks, MD, PhD, Moderna’s chief medical officer, said the company hasn’t yet generated the data necessary to make recommendations about booster shots or the definitive length of immunity.

“We’ll have to follow people for the year,” Zaks said at the J.P. Morgan conference. “We’ll boost some of them to see how well a boost works. We think there is an opportunity to boost, especially the ones at high risk, should you need it.”

An Adaptable Vaccine

Both the Moderna and Pfizer-BioNTech vaccines use mRNA technology. Other types of vaccines require manufacturers to create large batches of dead or weakened viruses, which can be a time-intensive process. With mRNA, scientists can easily swap out strains to protect against new variants if the virus mutates.

“These RNA vaccines can be produced very quickly,” Richard Kennedy, PhD, co-director of Mayo Clinic’s Vaccine Research Group, tells Verywell. “All we would need is the genetic sequence information and that can be obtained in a day. It’s possible if we see mutations and we need to reengineer a vaccine, with these RNA vaccines, that can be done very easily and quickly.”

As new, highly infectious variants spread globally, scientists are working to determine whether the currently authorized vaccines can protect against the new strains. Zaks said that it is scientifically possible for Moderna to reformulate its vaccine, expecting it to work without undergoing another large-scale clinical test. But the company’s ability to distribute a new, reforumalted vaccine may depend on regulators.

Determining the Length of Immunity

The vaccinations for some diseases, like mumps and measles, can provide immune protection for a person’s lifetime. Shiv Pillai, MD, PhD, director of Harvard’s Master of Medical Sciences in Immunology program, tells Verywell that some viruses like COVID-19, on the other hand, are harmful enough to the immune system that lifelong protection is unlikely.

“There are some viruses that do not completely compromise our immune responses, whereas this virus is very good at doing that at the time when you’re ill,” Pillai says.

Some data, however, shows that antibodies may protect against the disease for months after infection or vaccination. A study from November, which has not yet been peer-reviewed, shows that people who survived COVID-19 should have enough immune cells to protect themselves from the virus for more than six months, and possibly for years, after infection. 

It’s not yet clear how much longer a person who has been vaccinated will experience immunity compared to someone who was naturally infected and recovered from the illness. For now, experts say it’s likely people will have to be vaccinated yearly, much like with the annual flu shot.

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.