Kent Sepkowitz, MD, is an infection control expert at Memorial Sloan Kettering in New York City. The views expressed in this commentary are his own. View more opinion at CNN.

(CNN) As the COVID-19 pandemic continues to worsen, much attention in the US has been given to improving the availability of the diagnostic test.

Though testing is known to effectively reduce the risk of transmission, many experts are beginning to also associate more widespread testing with the statistic of greatest concern -- survival from the disease.

The connection seems straightforward. Consider two countries with large outbreaks.

In South Korea, the rate of testing has been quite high (3,692 tests per million people as of March 8), and its mortality among those infected quite low (about 0.6%, or 66 deaths, at last count).

By contrast, Italy tests about 826 people per million and its mortality among those with diagnosed infection is about 10 times higher, with more than 1,000 people dead from the disease.

Furthermore, stories abound of sick people in the US showing up at doctors' offices and hospital ERs, asking to be tested yet being sent away because no test is available or because they don't fit the testing criteria -- leading many to comment that the lack of testing is going to kill us all.

But we should be clear that more testing saves lives by preventing the next infection, not by allowing doctors to catch an individual patient earlier. The "treat early" paradigm works when there is an effective drug against the disease. Give antibiotics early for sepsis, you live; wait too long, you die.

The coronavirus, though, has no specific treatment. Indeed, the syndrome of a rapidly progressing lung failure that appears to kill COVID-infected persons is a familiar clinical condition. Many infections and exposures can cause the same problem; ICU specialists have been treating it for years.

So why does Korea, the poster child of testing, have so few deaths while Italy and its late-to-the-table testing program have so many? Is it only because more testing brings mild cases into the "infected" group, diluting the statistical impact of the handful of the very ill?

Doubtful. For now, it is because of vast differences in the affected patients. Soon and increasingly, it also will be due to overwhelmed hospitals and doctors and nurses.

Which is probably bad news for those hoping that the United States, which is currently way, way behind in testing for coronavirus, can somehow test itself out of the mess.

Plenty has already been written about how the population of Italy differs from much of the world. According to a UN report in 2015, 28.6% of the Italian population was 60 years old or older (second in the world after Japan at 33%). This compares to South Korea, where 18.5% of the population is at least 60 years of age, ranking 53rd globally.

The impact of this disparity is quickly shown in the analysis of coronavirus deaths in each county. In Italy, 90% of the more than 1,000 deaths occur in those 70 or older.

By contrast, the outbreak in South Korea has occurred among much younger people . There, only 20% of cases have been diagnosed in those 60 years old and up. The largest affected group is those in their 20s, who account for almost 30% of all cases.

Then there is gender. The gender split in COVID-19 cases worldwide is about 50-50, but there are gender differences in survival. According to data from the original outbreak in China, the overall death rate is 4.7% in men versus 2.8% in women -- a whopping difference. Which is good news for South Korea, where 62% of cases occur among women.

Smoking is another factor clearly associated with poor survival. Smoking rates are about the same between the two countries: 24% for Italians and 27% for South Koreans. But gender differences among smokers are widely different: In Italy, 28% of men versus 20% of women smoke, while in Korea, it is about 50% of men and less than 5% (!) of women.

In other words, South Korea has an outbreak among youngish, non-smoking women, whereas Italy's disease is occurring among the old and the very old, many of whom are smokers. (We do not know the male-female breakdown of Italy's cases).

These basic demographic distinctions explain the difference in death rates between these two hard-hit countries -- as well as helping to explain why Seattle, with its nursing home outbreak, accounts for such a large proportion of US coronavirus deaths.

To understand exactly what is happening, we need daily case updates to include information about age and sex.

The blundering lack of an effective testing program in the US is an unconscionable failure and has led (and will lead) to more transmission of COVID-19.

But it is important to recognize that survival with the infection is a completely other matter, one that will require very different investments, training, and expertise.

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The optimal program will have special beds to prevent bed sores, pharmacists with understanding of how medications are cleared differently in the elderly, and nurses familiar with frailty. Simply testing more and testing harder will not save the lives of the thousands of already infected Americans.

Better preparation might. And given the glaring differences in the outbreaks in South Korea and Italy, it is time to assemble an expert panel of geriatricians, social scientists, ICU specialists and others to sort out how best to protect and, when necessary, treat coronavirus in the elderly.