WASHINGTON (Reuters) – Senator Edward Markey, a Democrat and online privacy advocate, said in a letter released Wednesday that any digital coronavirus contact tracing should be voluntary, transparent and collect only the information needed to identify who might be at risk of contracting the respiratory ailment that has killed more than 45,000 people in the United States.

Markey urged President Donald Trump’s administration to balance public health needs as states seek to allow businesses to reopen their doors with the privacy rights of individuals who may be monitored.

Alphabet’s Google and Apple said recently they were collaborating on technology to create smartphone apps that would help identify people who have crossed paths with a contagious person and alert them.

“The federal government must provide leadership, coordination, and guidance to ensure that contact tracing efforts are effective and do not infringe upon individuals’ civil liberties, including the right to privacy,” Markey wrote in a letter to Vice President Mike Pence.

Markey urged that any contact tracing be limited to what is needed to track disease exposure, include investment in public health, and be voluntary, subject to enforceable rules and transparent about what data is collected and what happens to it.

He urged that a minimum of data be collected and that it be kept securely and discarded in a timely fashion.

Markey’s concerns echoed those of fellow Democratic Senator Richard Blumenthal, who has said that the companies face a “rightfully skeptical public” when it comes to privacy.

Republican Senator Josh Hawley, a frequent critic of the Big Tech companies, sent a letter on Tuesday to Google’s chief executive, Sundar Pichai, and Apple CEO Tim Cook to demand that they be liable for any privacy lapses in contract tracing.

“If you seek to assure the public, make your stake in this project personal,” Hawley wrote. “Make a commitment that you and other executives will be personally liable if you stop protecting privacy, such as by granting advertising companies access to the interface once the pandemic is over.”

Apple and Google did not immediately respond to a request for comment.

Previously, they have said that “privacy, transparency, and consent are of utmost importance.” The companies have said that the technology – planned to be released in mid-May – would not track users’ locations but their interactions, that interactions would be anonymized and nothing would be monetized.

(Reporting by Diane Bartz; Editing by Leslie Adler)