On Friday, President Trump announced “Operation Warp Speed,” a funding and logistics partnership between the government and pharmaceutical companies to develop, manufacture and distribute hundreds of millions of doses of a covid-19 vaccine by the end of 2020. Comparing the effort to the Manhattan Project that produced the atomic bomb, Trump acknowledged the plan would be “risky and expensive.” While the timing may offer hope to those tired of social distancing and help Trump’s reelection campaign, the timeline for Operation Warp Speed is probably unrealistically ambitious.

There are even questions about the scientific feasibility of making an effective vaccine — not just this year, but in the near future.

While on Monday biotech company Moderna reported promising results from early human trials for one potential coronavirus vaccine, we shouldn’t lose sight of the fact that there are miles to go before we have millions of doses of an effective vaccine. The history of large-scale, international efforts to develop and distribute vaccines has produced mixed results. Some, like the polio vaccine and the eradication of smallpox, were quite successful. Many others, despite decades of scientific focus and billions of dollars in investment, were not.

These failures — as well as the relative success of low-tech prevention strategies and drugs that treat virus patients — show the advantages of fighting the pandemic in a balanced way, one that combines the quest to develop a vaccine with efforts more likely to pay off.