The incidents followed more than a thousand ransomware attacks on American cities, counties and hospitals over the past 18 months. The attacks, once treated as a nuisance, have taken on greater urgency in recent weeks as American officials worry they may interfere, directly or indirectly, with the November election.

A ransomware attack in Germany resulted in the first known death from a cyberattack in recent weeks, after Russian hackers seized 30 servers at University Hospital Düsseldorf, crashing systems and forcing the hospital to turn away emergency patients. As a result, the German authorities said, a woman in a life-threatening condition was sent to a hospital 20 miles away in Wuppertal and died from treatment delays.

One of ERT’s clients, IQVIA, said it had been able to limit problems because it had backed up its data. Bristol Myers Squibb also said the impact of the attack had been limited, but other ERT customers had to move their clinical trials to move to pen and paper.

In a statement, IQVIA said the attack had “had limited impact on our clinical trials operations,” and added, “We are not aware of any confidential data or patient information, related to our clinical trial activities, that have been removed, compromised or stolen.”

Pfizer and Johnson & Johnson, two companies working on a coronavirus vaccine, said their coronavirus vaccine trials had not been affected.

“ERT is not a technology provider for or otherwise involved in Pfizer’s Phase 1/2/3 Covid-19 vaccine clinical trials,” Amy Rose, a spokeswoman for Pfizer, said.

Companies and research labs on the front lines of the pandemic have been repeat targets for foreign hackers over the past seven months, as countries around the world try to gauge one another’s responses and progress in addressing the virus. In May, the F.B.I. and the Department of Homeland Security warned that Chinese government spies were actively trying to steal American clinical research through cybertheft.