Starting late last month, yet another COVID-19 outbreak hit a nursing home in the Monadnock Region, this time Keene’s Alpine Healthcare Center.

But this outbreak is different than the others. While most occurred before or at the start of vaccine distribution, Alpine’s started after a majority of its residents and employees had received their full dose, according to its owner, Avi Goldstein.

This left people wondering how Alpine can be seeing an outbreak.

According to local health experts, it’s possible to contract the virus after vaccination, though it’s rare and symptoms are less severe.

“It’s important to remember that no vaccine is 100 percent effective,” said Dr. Michael Lindberg, chief medical officer at Monadnock Community Hospital in Peterborough. “That is true with the COVID vaccines. As good as they are, they aren’t 100 percent.”

Three vaccinations — made by Pfizer-BioNTech, Moderna and Johnson & Johnson’s Janssen Pharmaceuticals — were approved for emergency use by the Food and Drug Administration this winter.

Like other vaccines, such as the flu shot, these work by teaching the immune system how to recognize and fight the virus that causes COVID-19. It typically takes two weeks after vaccination for the body to build immunity against the virus, according to the Centers for Disease Control and Prevention.

Because of this, it is possible for a person to get COVID-19 before or just after vaccination, and then get sick because the body hasn’t had enough time to develop protection.

People are considered fully protected two weeks after their second dose of the Pfizer or Moderna vaccine, or after the single dose of Johnson & Johnson’s, the CDC says.

Lindberg said that while possible, it’s “very uncommon” for someone to become infected with COVID-19 after vaccination.

“You’re guaranteed to make the news if you do,” he joked.

At Alpine — one of five outbreaks statewide being monitored by the N.H. Department of Health and Human Services — 15 residents and seven employees had tested positive as of Thursday afternoon.

A rare occurrence

Clinical trial data from the three vaccines approved in the U.S. showed that few people contracted COVID-19 after they’d been immunized.

Pfizer’s trial of about 22,000 people reported only eight cases of COVID-19 one week after the second dose. For Moderna, 11 of the roughly 15,000 participants were diagnosed two weeks after their final shot.

Johnson & Johnson’s trials show slightly higher infection numbers (173 out of 28,000 people after 14 days). But that lower efficacy rate is because its trial spanned multiple countries and had to contend with several other coronavirus variants that have emerged in recent months, according to Dr. Aalok Khole, an infectious disease physician at Cheshire Medical Center in Keene.

“So yes, you are going to have breakthrough cases who get COVID after getting vaccinated, but it’s not really common,” Khole said.

He added it’s important to note that only 19 of the Johnson & Johnson cases were considered severe.

That’s because even if you do test positive for the viral disease after being vaccinated, the symptoms are going to be much milder, according to both doctors.

“The real role of vaccines is to try and prevent moderate to severe illness, hospitalizations and deaths, which all three of the vaccines that are currently in use have shown,” Khole said.

In addition to reducing deaths and suffering due to severe symptoms, this is important because if there is an increase in hospitalizations or deaths, health care systems could become overwhelmed.

Three key principles

How well the vaccines prevent people from spreading the virus that causes COVID-19, even if the person doesn’t have symptoms, is still being studied by scientists.

Early research suggests they do prevent transmission, the CDC says, but this has yet to be confirmed.

Regardless, Lindberg said, the more people are vaccinated, the more people in the community will likely become protected.

“It’s protecting yourself and protecting those around you,” he said. “You are reducing your risk of getting the disease, spreading the disease or silently carrying it. ... It really makes you a patriot because you are protecting others, not just yourself.”

While research continues, Lindberg and Khole — along with other health experts nationwide — urge people to keep practicing COVID-19 safety protocols, whether they’ve been immunized or not.

“Until we reach a point where a significant portion of the community is vaccinated and infections remain low, it brings us back to the three key principles: masking, physically distancing and hand hygiene,” Khole said. “... It is too soon to take our eyes off the ball.”

Olivia Belanger can be reached at 352-1234, extension 1439, or Follow her on Twitter @OBelangerKS.