In August 2020, Virginia became the first state in the nation to launch an app to track individual exposure to COVID-19.

With the rollout of MassNotify on Tuesday, Massachusetts became the 29th.

Ramesh Raskar — a professor at the Massachusetts Institute of Technology and founder of the PathCheck Foundation, a nonprofit that helps develop digital contact-tracing apps — said MassNotify has come online “definitely too late.”.

“I think everybody is disappointed that it took so long,” Raskar said.

“This was a no-brainer to launch an app that other states had already launched,” Raskar added.

PathCheck has worked with other states — including Alabama, Hawaii, Louisiana and Minnesota — to launch their apps.

It offered its services to Massachusetts but was not chosen, Raskar said.

MassNotify, a free service developed in conjunction with Apple and Google, works anonymously and “does not track” users or divulge their information, the state said Tuesday in its announcement.

She called the launch of MassNotify at this stage in the pandemic “somewhat baffling.”.

“It seems to show a lack of understanding about public behavior with respect to these apps, which is that people are more likely to use them if they think that this pandemic is still going on,” Kreps said.

Jeffrey Kahn, director of the Johns Hopkins Berman Institute of Bioethics, said exposure-notification apps could still benefit individuals who are vaccinated, like himself.

Since his vaccination, though, Kahn said he has been out and about.

“In some sense, it’s now much more important for me to know if by going someplace I might have been exposed if that alert comes to me, so in some sense it’s more important now than it was before,” Kahn said.

Philip Landrigan, director of the Global Public Health Program at Boston College, said the consensus is that exposure-notification apps are only somewhat beneficial to public health

Landrigan said it would have been preferable if Massachusetts had implemented the app sooner, but that it probably would not have had a significant effect

Ryan Calo, codirector of the University of Washington’s Tech Policy Lab, said Massachusetts should continue to focus its efforts on vaccinations, not exposure notification