Groton — A new antiviral medicine is being developed by Pfizer Inc. for the treatment of COVID-19, and the company's laboratories here, where hundreds continue to work in the midst of the pandemic, will be helping to ready the compound for possible clinical trials expected to start this summer.

New York City-based Pfizer said in a news release Thursday that it is developing a so-called protease inhibitor that has shown promise in fighting the coronavirus. Initial screening has indicated the lead antiviral drug candidate as well as other similar compounds are potentially "potent inhibitors" of the coronavirus known in scientific circles as SARS-CoV-2, the release said. 

The summer start date for clinical trials is "three or more months in advance of earlier estimates," according to the release. "Researchers and scientists have been relentlessly working to develop an investigational antiviral compound to treat (coronavirus)."

Confirmation of the initial optimistic results will be required before going forward, but the company said it already is buying materials in anticipation of clinical studies to test the drug on human volunteers. Among the questions on the table is whether the antiviral medicine will be suitable for intravenous use.

"Groton Labs are responsible for ensuring the safety of the product and in scaling up production of the drug for use in the first clinical trials and other studies," Steve Danehy, a Pfizer spokesman, said in an email.

Pfizer's stock price closed Thursday at $35.59, up more than 2% from Wednesday.

In addition to the antiviral studies, Pfizer will be testing a warhorse of its current medicines, the rheumatoid arthritis pill Xeljanz, to see if it helps COVID-19 patients. Xeljanz, discovered and developed in the Groton labs, is being tested in Italy, which is one of the countries hardest hit by the pandemic. Another medicine, azithromycin, also has been studied by Pfizer scientists as a possible weapon against the coronavirus.

In addition, Pfizer and the German firm BioNTech SE have announced a global collaboration to co-develop a new coronavirus vaccine. Clinical trials will get underway in the United States and Europe as early as the end of this month, and Pfizer said the companies could potentially have millions of vaccine doses ready by the end of this year with speedy regulatory approval, and hundreds of millions on the market by 2021.

"We are leaving no stone unturned as we explore every option to help provide society with a treatment or cure," said Albert Bourla, Pfizer's chairman and chief executive, in a statement.

l.howard@theday.com