Millions of New Jerseyans have been vaccinated for COVID, but how long will it last?

New Jersey is well on pace to vaccinate 70% of the adult population, estimated at 4.7 million individuals. As of Thursday, 1,630,837 have been fully vaccinated. Another 2,809,654 have had their first shot of the Pfizer or Moderna vaccine, and are awaiting their second dose.

State health officials say 9-in-10 people who get their first shot, do return for the second. By the end of April, the state is on pace to have at least 4,440,491 residents fully immunized. At the current pace, the state could exceed 5 million people fully vaccinated by Memorial Day. But how long will the protection last?

The question of how long you are protected from COVID-19 with the currently approved vaccinations is one we are asked a lot. There has been no easy answer. It could be a few months or a year or longer. In initial clinical trials, immunity lasted at least three months, but that was the time period participants were monitored.

Pfizer has updated their long-term study to say protection lasts at least six months, but again that is the time participants were monitored.

There has been some anecdotal evidence in studies that suggest the vaccines could last up to three years, but no long-term data to support that.

The spectrum of commonly used vaccine in terms of long-term efficacy varies greatly. For example, influenza vaccines protect for only a few months, and an updated vaccine is needed annually. By contrast, the measles vaccine offers lifetime protection.

Most medical experts seem in agreement that the COVID vaccine will be more like the influenza vaccine and require an annual booster. Chunhuei Chi, director of the Center for Global Health at Oregon State University's College of Public Health and Human Sciences, says it "is very likely that for [the] COVID-19 vaccine, given that the length of immunity the vaccine generates is limited, we may have to be vaccinated annually."

White House Chief Medical Advisor Anthony Fauci concurs but says much more study is needed. The CDC is monitoring for what Fauci termed "breakthrough infections," or infections that get past the immune system of someone who has been vaccinated.

“If it looks like after a year and a half, the antibody levels go down and people start to get breakthrough infections," Fauci explains, "then we know that after a year and a half, we probably have to give them a boost.”

The length of immunity could also vary from person-to-person. Dr. Chi says people with a stronger immune system will produce more antibodies and ultimately have a longer lasting immunity.

The good news for those who have been vaccinated, experts say, is that all of the vaccine currently approved provide strong protection from serious illness and are 100% effective at preventing death from COVID-19. Even more critical, doctors say, the vaccines eliminate potential hosts and the ability for the virus to mutate into versions that are resistant to vaccine immunity.

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LOOK: Answers to 30 common COVID-19 vaccine questions

While much is still unknown about the coronavirus and the future, what is known is that the currently available vaccines have gone through all three trial phases and are safe and effective. It will be necessary for as many Americans as possible to be vaccinated in order to finally return to some level of pre-pandemic normalcy, and hopefully these 30 answers provided here will help readers get vaccinated as soon they are able.