Older teens are now eligible for the COVID vaccine, but will their vaccination rates catch up to those of their elders?

The couple’s 18-year-old son and 17-year-old daughter echo their father, and repeat stories they’ve seen on social media about unproven, potential long-term side effects from the vaccine.

“I will try to say, ‘Mommy did it, now you can, too,’ ” Megie-Maddrey said. “But it’s hard for me as a parent because I don’t know what the long-term effects are. They could find out something five or six years from now we really don’t know.”

So far, roughly 28 percent of Massachusetts 16- and 17-year-olds have gotten at least a first shot, state data show. Not all of them have been vaccinated since April 19, however. Some got their shots as early as mid-February, when vaccines became available to residents with two or more qualifying health conditions, including asthma.

But it’s too soon to say when — or whether — teen vaccination rates will catch up to those of their elders, half of whom have now received at least one shot.

Even parents who eagerly scrounged for their own vaccination appointments are asking more questions when it comes to scheduling a shot for their children.

Could there be long-term harms that won’t be apparent for years? Is it worth the risk of side effects to get a shot that protects against a disease that is usually mild in young people? And there’s plenty of scientifically dubious information to frighten parents linking vaccines to everything from reduced fertility to government surveillance.

Dr. Andrew Siesennop, a pediatrician at Tufts Children’s Hospital, said he is encountering quite a few families, like Megie-Maddrey’s, that are divided about the vaccine.

“As a parent myself, it’s the first thing I think about: what am I doing for my child?” Siesennop said.

He said he tells them that scientists don’t yet know the long-term effects of the shots, but that short-term they have proven safe for adults and that it’s better to get the vaccine than the infection. While it’s true that serious illness and death from COVID-19 are rare among children and teens, the virus could still mutate into a form more dangerous to young people, he said.

“Like any virus, if it’s passed from child to child, and person to person, mutations do happen,” Siesennop said. “There is no saying this virus may not become more dangerous to children in the future.”

Siesennop also urges young people to think about the risk to others from remaining unvaccinated: they can spread the infection to people who may be more vulnerable.

The debate over vaccinating young people is likely to intensify in the near future as Pfizer, whose COVID vaccine is the only one authorized for people 16 and older, seeks authorization for children as young as 12. The company earlier this month requested federal permission for emergency use approval after reporting preliminary data indicating the shots were safe and offered strong protection among 2,260 volunteers aged 12 to 15.

The other two vaccines used in the United States, from Johnson & Johnson and Moderna, are authorized for those 18 and older, but both companies have announced studies testing younger volunteers, including a Moderna trial that is testing the shots in children as young as 6 months.

Young people may feel more pronounced temporary side effects, such as pain near the injection site, headache, and fever, based on a review of Pfizer vaccine study volunteers that compared symptoms among those 18 to 55 versus those over 55.

But parents who are hesitant about the shots for their children say they are more worried about possible long-term effects.

Rodolfo Aguilar and his wife, both in their 50s, have gotten vaccinated. Still, the Randolph couple is debating whether to make appointments for their three children — a daughter, who will be 16 in June, and two sons, ages 17 and 23.

No one needs to tell the couple about the danger of COVID. Aguilar’s father-in-law died of it last April.

“This virus is nothing to mess around with,” Aguilar said.

But the couple is having trouble finding reliable information about the shots for teenagers and wants to first speak with their pediatrician about one particular worry making the rounds on social media.

“There have been speculation and rumors that the vaccination can make young people sterile,” he said. “I don’t know if it’s a rumor or a fact.”

Dr. Eve C. Feinberg, an infertility specialist and associate professor of obstetrics and gynecology at the Northwestern University Feinberg School of Medicine, said she’s been hearing that sentiment a lot.

“There is no biological plausibility of how this vaccine would cause infertility,” Feinberg said.

She points to data showing that several women in the Pfizer vaccine trials got pregnant after receiving the shots.

One false rumor that has become rampant on social media suggests that the spike protein on the surface of this coronavirus mimics another spike protein called syncytin-1 that is involved in the growth of the placenta during pregnancy. As a result, the rumor goes, the vaccine can interfere in pregnancy by attacking the wrong protein.

Not true, Feinberg said.

“Vaccines are very specific to the type of protein they are attacking and there is no crossover,” she said. “It’s like saying I am eating candy but it can mean a Snickers bar or gummies. Proteins in the body are the exact same way.”

Still, a sizable percentage of parents appear hesitant, according to a recent poll from the National Parents Union. Their March survey of 1,029 parents nationwide found that roughly 40 percent are either unsure about or opposed to vaccinating their children, a percentage largely unchanged since December.

Megie-Maddrey, the Lynn parent, knows she’s got a lot of work ahead of her to convince her husband and children, especially the couple’s 17-year-old daughter, Tatiana.

“It’s poison,” Tatiana said in an interview.

The teen said she came to that conclusion after speaking with her father, who has not been vaccinated, and her friends and researching on the Internet. She’s worried there might be adverse long-term side effects that haven’t yet been recognized.

Megie-Maddrey thinks she may have more luck convincing her 18-year-old son, a senior, to get vaccinated. Megie-Maddrey is reminding him that many universities will be requiring students to be vaccinated.

“He doesn’t want to live at home,” she said. “I have told him you will have to get the vaccine or you wont be able to live on campus.”

Kay Lazar can be reached at kay.lazar@globe.com Follow her @GlobeKayLazar.