As a physician and scientist who knows a lot about respiratory personal protective gear, I have been outraged about the severe shortages of the proper N95 masks that health-care workers on the front lines of the fight against the novel coronavirus epidemic should be wearing.

Doctors, nurses, respiratory therapists and others — especially those over 50 — who are caring for patients who have or may have covid-19 must be protected from becoming infected themselves. Not only do we need to keep the health-care workforce on the job to treat the rest of the population, there is a moral imperative to provide a safe workplace, especially in the context of a deadly viral pandemic.

And what do we find in cities like New York, New Orleans and Detroit where the pandemic is raging? We see severe shortages of the N95 masks in emergency rooms and hospitals. Even surgical masks, which provide some protection, are in short supply at many health-care facilities. Desperate health-care workers have resorted to unvalidated measures to find alternative methods of protecting themselves.

Many members of the public have responded to the urgent need of respiratory personal protective equipment (PPE) for health-care workers by sewing cloth masks. While this response is truly heartwarming, most cloth masks provide little actual protection from novel coronavirus infection and may give health-care providers a false sense of security when working around potentially infected patients.

High rates of both infection and death from covid-19 have been reported in China and Italy. In China, more than 3,000 health-care workers have been infected out of 81,000 total cases, including Li Wenliang, who died after being the first physician to try to alert the Chinese government about the risk of the outbreak in Wuhan.

At least 5,000 health-care workers have been infected in Italy out of over 92,000 total cases as of this writing. The risk of death due to covid-19 increases with age, with individuals aged 50 to 59 at three times the risk and those aged 60 to 69 at 10 times the risk of those between ages 30 and 49.

In the United States, there are over 500,000 physicians older than 50, representing just over half of the nations’ entire physician workforce. The average age of nurses in the United States is 51. A 48-year-old emergency department nurse in New York City died of covid-19 on March 24, and emergency department physicians have been reported to have developed severe covid-19 requiring intensive care in Washington state and New Jersey.

It is tragic that a country as wealthy as the United States cannot provide proper PPE to its health-care workforce during a deadly viral pandemic. There is little excuse for inadequate stockpiling of N95 masks and other PPE like surgical masks and gowns. The novel coronavirus outbreak in Wuhan was not the first viral epidemic of recent years — the severe acute respiratory syndrome coronavirus outbreak was in 2003, the Middle East respiratory syndrome outbreak started in 2012, and there have been periodic avian flu outbreaks. Why weren’t we better prepared?

Badly designed lines of authority in the federal government have failed to provide proper protection for health-care workers and a disorganized and poorly coordinated response has left states and cities fighting to outbid each other for purchases of desperately needed PPE for their health-care workers (and ventilators for their patients).

And even with an ineffective federal pandemic response team in place before the Wuhan outbreak, there was still sufficient time to prepare for spread of the virus to the United States. The severity of the novel coronavirus outbreak in China was recognized by the World Health Organization and U.S. intelligence agencies in fall 2019.

Yet what was President Trump’s response as late as February? It was “when it gets a little warmer, it miraculously goes away,” “just like the flu,” “a foreign virus,” and most incongruously, “The Coronavirus is very much under control in the USA. . . . Stock Market starting to look very good to me!”

Let me tell you, Mr. President, as a physician who takes care of patients at a public safety-net hospital, you never had the covid-19 pandemic under control. You were worried more about the stock market than the pandemic. It was a public health emergency that you failed to take seriously until it was too late and wide community spread is the result. Lives have been lost all over this country because of your failure to take seriously what your public health and intelligence experts were trying to tell you.

John R. Balmes, professor of medicine at the University of California at San Francisco and professor at the School of Public Health at the University of California at Berkeley, is a pulmonary and critical care specialist who cares for patients at Zuckerberg San Francisco General Hospital.