Dr. Tom Frieden is the former director of the US Centers for Disease Control and Prevention, and former commissioner of the New York City Health Department. He is currently president and CEO of Resolve to Save Lives, a global non-profit initiative funded by Bloomberg Philanthropies, the Chan Zuckerberg Initiative, and the Bill and Melinda Gates Foundation, and part of the global non-profit Vital Strategies. Resolve to Save Lives works with countries to prevent 100 million deaths and to make the world safer from epidemics. The views expressed in this commentary are solely those of the author.

(CNN) Covid-19 will become a pandemic. We don't yet know how severe it will be, nor do we know if the virus will spread to all continents, but it's already spreading widely in China, South Korea, Italy, Iran and elsewhere -- and thousands of undetected and infectious patients have been and continue to travel around the world.

This is unprecedented. Other than influenza, no other respiratory virus has been tracked from emergence to continuous global spread. The last moderately severe influenza pandemics were in 1957 and 1968; each killed more than a million people around the world. Although we are far more prepared than in the past, we are also far more interconnected, and many more people today have chronic health problems that make viral infections particularly dangerous.

Based on extensive planning for an influenza pandemic by many national and international experts, we must do eight things -- some immediately and some in the coming months -- as we shift from the initiation phase of the pandemic to the acceleration stage

Find out more about how Covid-19 spreads, how deadly it is and what we can do to reduce its harms. As many as half of people with infection have no symptoms, and at least 80% of those who do feel ill have only mild symptoms. In Wuhan, China, the reported proportion of diagnosed patients who die is now 3%. That's a substantial over-estimate; many patients weren't tested, many infected people don't have symptoms and hospitals were overwhelmed. The proportion could be as low as less than 1 in 1,000 -- 30 times lower -- and is unlikely to be more than 1 in 100. The actual rate makes a huge difference, not only to patients but also to decisions about interventions. Reduce the number of people who get infected. If it turns out that many of those infected become severely ill, this would justify drastic measures such as closing or curtailing hours of schools, limiting public gatherings and reducing social contact. The lower the risk of death from infection, the less sense it makes to take these and other actions that disrupt social and economic stability. In any case, spread can be minimized by quickly isolating those who are ill, cleaning potentially contaminated surfaces often and changing common routines. We need to get serious about little things that make a big difference: washing hands, covering coughs and, if we're sick, staying home or wearing a mask when we go out. Let's stop shaking hands for a while. I prefer the traditional Southeast Asian hands-together namaste greeting, although the elbow bump is fun. Protect health care workers. Even before Covid-19, far too many health workers and patients got infections in health care facilities. We need fast and drastic improvements in triage, treatment, cleaning and overall infection prevention. A shortage of medical masks is likely; we need to ensure health care workers have enough, as should household members caring for sick relatives and people who are ill and need to go outside. For health care workers, newer, longer-lasting technologies such as elastomeric and positive air pressure respirators could address an otherwise inevitable shortage of medical masks. Improve medical care and prevention of Covid-19. A vaccine is at least a year away, and success is uncertain. Treatments that hold promise need to be evaluated rigorously. In a moderately severe pandemic, there wouldn't be enough ventilators to support patients' breathing. Health facilities and health departments in the United States can prepare for a worst-case scenario by preparing -- with training, equipment, and detailed operational plans -- for a surge in the number of patients who seek care and for the subset of those who need to be mechanically ventilated, including through ventilators available from the Strategic National Stockpile. Protect health services. During the 2014-2016 Ebola epidemic in West Africa, more people died because of disruptions of day-to-day health care than died from Ebola. Telemedicine needs to become much more accessible, and people with chronic conditions should receive three months of medications whenever possible, in case there are supply disruptions. Routine vaccinations and other preventive services need to be preserved. Support social needs. Patients and their families will need support, especially those who are isolated and less familiar with virtual or delivery services. Continuing to support individuals and groups ranging from community centers to nursing homes will require detailed plans. Protect economic stability. Continuing to plan, teach, learn and work will reduce disruption. Businesses need to be ready to maximize telecommuting, increase cross-training and operate with as many as 40% of their staff ill or quarantined. Mission-critical enterprises need practical plans to continue to operate. Invest in public health. It will cost about $1 a person per year for at least a decade to build the health protection systems needed in Africa and Asia. That's a lot of money -- about $25 billion -- but a tiny fraction of what a preventable epidemic such as this one can cost. (SARS cost $40 billion; estimates for the potential cost of Covid-19 exceed $1 trillion.)

The virus and appropriate interventions will behave differently in high-resource than in low-resource areas, depending on crowding, capacity for diagnosis and treatment, and ability to reduce spread. We don't yet know if Covid-19 will result in thousands, hundreds of thousands, or millions of deaths.

Read More