As of July 9, there were five confirmed cases of the delta variant in Maine, with another five cases under investigation. MaineHealth, the state’s largest hospital network, had reported as many as 18 cases of the variant as of last week and had forwarded its samples to the Maine CDC for full genetic sequencing.

The variant, also known as B.1.617.2, is especially dangerous to unvaccinated and immunocompromised people, prompting health officials in states like California and Missouri, as well as at the World Health Organization, to urge vaccinated individuals to once again don their masks to prevent transmitting the virus to those who are most at risk.

But what does that mean for people in Maine? Here’s what we know so far.

What is a variant and how is the delta variant different from the “regular” COVID-19?

Viruses are constantly mutating, creating variants that make the virus stronger or weaker.  The weaker mutations will usually die off, while the stronger mutations, the ones that result in higher transmissibility or that make the virus more virulent (meaning it gets you sicker), will survive and spread. Variants are genetically distinct from a main strain, but not different enough to be termed a distinct strain.

The U.S. Centers for Disease Control and Prevention has three classifications for variants: A variant of interest, a variant of concern and a variant of high consequence. The delta variant is classified as a variant of concern, meaning that it spreads faster and more easily, results in more severe disease and that it may evade some of the immunity the vaccine is supposed to provide.

Dr. Dora Anne Mills, MaineHealth’s Chief Health Improvement Officer, said the delta variant seems to check most of these boxes. It is roughly 225 percent more contagious than the original iteration of COVID-19.

Dr. Laura Blaisdell, a pediatrician from South Portland and an infectious disease expert, said the average person infected with the original coronavirus strain would infect two to three other people. A person infected with the delta variant, she said, will spread it to four to six other people.

The vaccines are still extremely efficient at protecting against the variant, but clinical studies suggest that those who have had only one dose of the vaccine may be slightly less protected against the delta variant than they are against the regular COVID-19.

A Scottish study published last month found that unvaccinated patients with delta were twice as likely to be hospitalized than those sick with the alpha variant first identified in the U.K., and a study from Canada published this month indicated a significant increase in the risk of hospitalization, ICU admission, and death from the delta variant versus previous variants and strains.

The delta also appears to present with slightly different symptoms than the original strain. Symptoms are similar to the common cold, such as a headache, sore throat and runny nose, as well as a fever and cough, but often does not carry the loss of taste and smell commonly recognized as an indicator of COVID-19. Therefore, Mills said, if someone thinks they only have a summer cold, they should probably be tested for COVID-19.

Who is most at risk from this new variant?

People who are unvaccinated, those who have only had one dose of the vaccine, those who are immunocompromised or immunosuppressed, and elderly people with underlying health conditions, even if they are vaccinated, are most at risk. People who fall into those categories are encouraged to continue wearing masks, keeping 6 feet of distance and following all other coronavirus mitigation practices.

I’m fully vaccinated. Am I protected? Do I need to start wearing a mask again?

The vaccines are doing their job and remain the No. 1 source of protection against COVID-19. They are protecting people from serious disease, hospitalization and death, but officials are still seeing some “breakthrough” cases of COVID cropping up in patients who are fully vaccinated.

According to Mills, the majority have been either asymptomatic or with mild infection or are immunocompromised or elderly with underlying health conditions.

As vaccine rates increase, it’s likely that there will be more positive cases in people who are fully vaccinated, she said. This is a matter of “denominators,” rather than proof the vaccine has lost its effectiveness, she said.

The Maine Centers for Disease Control and Prevention has reported 541 breakthrough cases, a tiny fraction among the more than 750,000 people who have received at least a first dose of a vaccine.

As for masks, Mills views them as an extra layer of protection for individuals and their communities, and many health officials are once again urging Americans to mask up, expressing concerns that vaccinated people could become infected by the delta variant but not show symptoms and then transmit it to those who are unvaccinated.

Health officials in St. Louis and in Los Angeles County have recommended that people resume wearing masks.

Does this mean vaccinated people will require boosters?

It’s still too soon to say whether we will need boosters, whether for overall immunity from the virus or for any of the specific variants. Scientists have mixed opinions on whether the data indicates that a booster is effective and provides substantial additional protection.

Pfizer-BioNTech announced last week that it is planning clinical trials for a booster shot that would potentially be used against delta.

There are some discussions around whether people who are immune-suppressed might need a third booster, Mills said, but the “jury is out. … It’s all so nascent.”

Federal officials soon may have an answer. The Washington Post reported on Thursday that a federal advisory panel is expected to consider whether healthcare workers should be allowed to give coronavirus booster shots to patients with fragile immune systems. Top U.S. health officials have said an additional dose of vaccine is not widely needed.

Next week’s panel discussion will not address Pfizer’s request for regulatory approval. Rather, it will focus on updating clinical considerations for coronavirus vaccines, which doesn’t require an advisory panel vote.

I’m hearing that the variant is causing more infections in children. Is this true? How will it impact schools in the fall?

People who are unvaccinated face a higher risk from the delta variant than people who are, and without an approved vaccine for anyone younger than 12, most children remain unvaccinated.

For much of the pandemic there has been the idea that kids just don’t get COVID-19, said Blaisdell, the South Portland pediatrician, and if they do, they don’t get that sick. “But we’re starting to see more illness in children with these variants,” she said, attributing the increased rates to both how contagious the new variant is, as well as how closely children play and interact with one another.

It’s too soon to say how it might impact school in the fall, but Blaisdell worries that schools, which last year managed to largely escape becoming virus hotbeds, may see more community transmission.

Masks may need to stay on for younger children, and distancing, hand hygiene and health screenings will almost certainly stick around.

“Most of us feel like we’re going into the waning hours of the pandemic, but the pandemic certainly isn’t over for children,” she said, adding that it’s now more important than ever for parents and family members to get vaccinated.

“Because children cannot get vaccinated, we need to provide a protective cocoon around them,” she said.

How far are we from having a vaccine for children under 12?

It’s too soon to say exactly when a vaccine will be readily available for children, but experts hope to see something this fall.

Pfizer and Moderna are doing clinical trials to see how the vaccines work in younger children – if they’re safe and what the right dose may be. It’s a lengthy process, there’s a greater burden of proof for efficacy and safety since children are such a vulnerable population, Blaisdell said. Still, she hopes to see a vaccine at least for school-aged children, if not those as young as 2, by Thanksgiving.

My family has a summer vacation planned. Is it safe to travel?

“It can be safe to travel and it can be dangerous to travel,” Blaisdell said, it just depends on how you do it.

Families should consider what their risk factors are and what level of risk they are comfortable with. Who are you traveling with? Who are you going to visit? Where are you going?

Traveling by car a few states away is different from an international flight, Mills said, and vaccinated adults visiting vaccinated friends is different than unvaccinated children going to see immunocompromised grandparents.

However, with all the “layers” of precautions we have now, like masking, social distancing, hygiene and improved ventilation, “it’s possible to travel relatively safely compared to a few months ago,” Mills said.