We’re battling a 21^st century pandemic, mainly using measures that are the equivalent of pistols. Meanwhile, the rocket launchers and cruise missiles that emerging evidence suggests could be used in this war sit largely idle.

The gap is vast between current scientific knowledge about Covid-19 and both public perceptions and many of the policies being deployed. If we redirected our energies from concerns that relate to a minuscule proportion of infection events and instead prioritized measures that more closely align with the data, much sickness and death­ could be prevented (and many needless worries allayed).

During the AIDS crisis, I was among the first researchers to argue that certain unorthodox approaches, such as voluntary circumcision of adult males, could prevent HIV. Although initially met with disbelief and or even ridicule, several of these strategies were eventually adopted by the UN, CDC, and other international agencies. With the current pandemic, we cannot afford to again wait years to enact more effective policies.

Widespread concern about infection from brief proximity to others or, from touching surfaces and objects are inconsistent with what scientists now know about how Covid-19 is and is not spread. And while some studies have suggested masks can reduce infection risk and may help limit the disease’s severity, the data is clear that masks are only partially effective. As the prominent coronavirus scientist Michael Osterholm has cautioned, we should not use “poorly conducted studies to support a contention that wearing cloth face coverings will drive the pandemic into the ground.” While neither Osterholm nor other experts oppose mask use, existing evidence suggests they are somewhat akin to pistols: useful in situations where distance cannot be maintained, especially indoors, but not a game-changing weapon for vanquishing Covid-19.

On September 9, these issues struck close to home, when my sister tested positive for the coronavirus. She suffers from serious preexisting conditions and required hospitalization for over a week. While now recovered, the question looms: how did she — and almost 50 other residents and staff of her San Francisco nursing home — acquire the virus during a few weeks? The entire facility had been locked down tightly for six months. No one other than staff members, one of whom evidently was the source of the outbreak, were allowed in or out unless for medical emergencies, and everyone wore masks at all times.

Fifteen feet of distance, constant mask use, and a thick plastic curtain separated my sister from her roommate, who had tested positive a week earlier. Yet my sister’s subsequent positive test is consistent with what hundreds of experts have been suggesting: that “aerosol” transmission in indoor spaces with poor air circulation and ventilation can enable a sufficient quantity of virus to eventually accumulate.

So, what can be done?

To begin, it is time to stop worrying and fighting so much over measures which leading scientists have shown to have minimal impact. Most Covid-19 cases have been linked, through contact tracing and other studies, to domestic residences, nursing homes, prisons, meat-packing plants, factories, and cruise ships. In such settings, people spend many hours a day breathing the same air.

In contrast, when you touch something previously touched by someone else, or if they walk past you on the street, infection is extremely unlikely, as informed by our growing biological and epidemiological understanding of this coronavirus. As I explain in Facing Covid Without Panic, typically the level of viral exposure in such fleeting situations is well below the threshold needed for infection to take hold.

While physical distancing and mask wearing are useful, they clearly are not sufficient to prevent ongoing outbreaks. Rather, we need to focus on prevention strategies that could actually make a substantial dent in the pandemic, while we also continue to work on developing effective vaccines and treatments. 

Whenever possible, we should emulate those European and Asian nations that have urged their populations to conduct business and other activities outdoors. Investigators have estimated that outdoor infection risk is some19 times lower than indoors. This extreme difference is due to various factors, including dissipation of droplets in the air (especially when windy) and the deactivating effects of ultraviolet radiation, heat and humidity. If schools in frigid Denmark can hold classes outdoors, why can’t temperate California?

When people do need to be indoors — and where windows cannot be opened to allow circulation of fresh air — especially in high-risk settings such as nursing homes, meat-packing plants, and prisons, it is time for Covid “Marshall Plan.” We need an ambitious infrastructure campaign to bring together private and public investment for introducing effective circulation, filtration and/or UV systems in such places with poor ventilation, similarly to what the airline industry has been implementing. Such measures, while often costly, would also produce other important, long-lasting health benefits, as championed by the budding “healthy buildings” movement.

Keep wearing masks, particularly in crowded indoor settings, but let us not kid ourselves that this alone will defeat the pandemic. No modern military would discard its pistols, yet neither would any base its strategy on such limited weapons. It’s time to bring out the big guns.

Daniel Halperin, PhD is author of “Facing Covid Without Panic” and a May 29 Washington Post article on reopening schools, and currently is Adjunct Full Professor at Gillings School of Global Public Health at the University of North Carolina, Chapel Hill.