Mark Zuckerberg and Bill Gates are stepping in on the coronavirus in San Francisco and Seattle, Recode

When government falls short, tech billionaires may be able to fill the void.

A pair of Silicon Valley philanthropists, Mark Zuckerberg and Bill Gates, have announced new attempts to expand testing for the novel coronavirus in their local areas. They are playing a much-needed role at a time when billionaire philanthropy is criticized more than ever for supplanting government action. There are now more than 700 coronavirus cases in the United States and at least deaths as concern rises among Americans.

Zuckerberg’s philanthropy, the Chan Zuckerberg Initiative, and its affiliated CZI Biohub, on Tuesday announced that it would purchase two clinical diagnostic machines to quadruple the ability for testing and diagnosing possible cases of the disease in the San Francisco Bay Area. The region has been hamstrung by a testing bottleneck that makes it difficult to ascertain how much the virus has spread. CZI said its machines would be in place likely by next week.

Another region that is home to an outbreak, the Seattle area, is also turning to its own local billionaire philanthropists. The Bill and Melinda Gates Foundation said this week that it is going to fund its own testing kits that Seattleites can use at home and send in for analysis. A Gates official told the Seattle Times that “this has enormous potential to turn the tide of the epidemic,” although the test results’ timing is less clear.

Zuckerberg’s philanthropy was similarly optimistic about its impact.

“Procuring these new diagnostic machines will have a significant impact on our ability to respond to the outbreak in a more streamlined way,” the head of the CZI Biohub, Joe DeRisi , said in a statement.

But major charitable commitments from philanthropies like these are, in general, more controversial than ever. That’s not to say that the Gates Foundation and CZI aren’t making an impact. But it’s that a growing chorus of critics argues that private philanthropists use major gifts as a tool to skew public policy – and that it is the role of government, not billionaires, to address our common problems.

The coronavirus gifts, though, are something of an answer to this new, in-vogue attack. After all, the American government has had weeks to beef up its testing regimen, and it has failed . A common defense of billionaire philanthropy is that these billionaires are not supplanting government action but merely supplementing it, filling in the holes that the government is unable to address on its own.