Skip to Main Content

Fifteen years ago, in response to the threat of H5N1 avian influenza, my team at the White House developed the National Strategy for Pandemic Influenza. We recognized that the world would have to make its way through the first wave of a pandemic, and possibly the second wave, without a vaccine.

Led by Drs. Richard Hatchett and Carter Mecher, we worked with disease modelers and key stakeholders to develop a strategy of early, coordinated interventions such as school closures and social distancing to delay and lower the peak of illnesses and to reduce the total number of cases in communities. Two years later we published this guidance, along with this now almost iconic graphic. Today this strategy is called flattening the curve.


Flatten-the-Curve Covid-19
From the CDC’s “Interim Pre-pandemic Planning Guidance: Community Strategy for Pandemic Influenza Mitigation in the United States” Centers for Disease Control and Prevention

When explaining the strategy, we asked people to visualize each intervention, such as school closure, as a slice of Swiss cheese — an imperfect barrier to virus transmission as represented by the holes in the cheese. When multiple partially effective interventions are combined early in an outbreak, like stacked Swiss cheese slices, the gaps are covered and virus transmission is slowed, or even stopped.

Governments around the world have implemented variations on this strategy against Covid-19. South Korea was successful with a particularly effective slice: robust testing, contact tracing, quarantine, and isolation. Once it was recognized that Covid-19 was being transmitted in the U.S., states took multilayered approaches to avoid a catastrophic burden on hospitals and save lives. We are just beginning to see the impact of these efforts.

We can’t change the past, but we have a second chance to show we can contain this virus. Widespread stay-at-home restrictions can eventually suppress virus transmission to a level that existed several weeks ago, rewinding the epidemiologic clock and making containment possible once again.


At that point, we can take three steps that will allow us to relax the most restrictive social-distancing measures and reopen our cities:

Require everyone to wear a mask. A cloth mask does not provide substantial protection to the person wearing it, but it can prevent an infected person from transmitting Covid-19 to others. In the lingo of epidemiology, this is called source control. The Centers for Disease Control and Prevention has already recommended that the public use face coverings and published DIY mask instructions, but this is not enough. We need a directive — not just a recommendation – that everyone should wear a cloth mask in public places. This could substantially reduce transmission in communities while making it possible for people to leave their homes. It would also address the thorny problem of transmission of the virus by people who don’t have symptoms.

Several apparel manufacturers have begun producing cloth masks, making it feasible for everyone to have one. Universal source control could be a highly effective layer of Swiss cheese that would allow us to relax other more restrictive measures.

Bring testing to the people. As we relax social distancing, the way to prevent outbreaks is to quickly find people with the virus and stop onward spread through testing, contact tracing, isolation, and quarantine. This requires the availability of testing everywhere, with results available in hours, not days.

To make this work, testing must be available when and where people need it. Drive-through and pop-up testing centers will play a role, but we should also bring testing to people, just as we do with rideshare services and food delivery. Hiring and training a workforce would augment under-resourced public health departments and put people back to work. Workers with medical training could collect samples, supported by an army of non-medical personnel with appropriate personal protective equipment to safely carry out contact tracing and provide guidance on voluntary isolation and quarantine. The technology platforms that power the gig economy could be repurposed and scaled to make this possible across the nation.

The most important enabler of just-in-time testing will be the general public, whose buy-in and sense of personal responsibility can ensure that testing happens when it is needed. It would be ideal for people to seek a test the moment they develop symptoms, as reflexively as grabbing a thermometer if they have a fever.

And if they have Covid-19, isolating themselves and asking their contacts to voluntarily quarantine can help them be the end of the chain of transmission rather than another link in it.

Prepare for Covid-19 rebounds. As we are seeing in Asia, relaxation of social interventions can lead to a resurgence of virus transmission. This will be a risk until we have substantial immunity in the population from a vaccine and/or previous exposure. We need to define triggers to reinstate social interventions early and in a coordinated manner, such as laboratory-based surveillance in the community or our inability to link new cases to known cases. Those triggers and actions should be understood and exercised by all communities.

After this wave of the Covid-19 pandemic, we will have a “new normal” way of living and working that will provide a layer of protection compared to our pre-pandemic life. Early on, we can expect fewer public gatherings, less travel, more social distancing in the workplace, and more virtual interactions. These will certainly reduce the risk of rebound. And if we’ve successfully deployed the first two solutions — masks and testing — we can avoid the most extreme measures that we are experiencing now.

These interventions are the layers of Swiss cheese that can let us reopen our cities while preventing a resurgence of infections. They’ll enable us to flatten a second wave of the pandemic if it comes in the fall — or sooner — but most importantly they will buy us much-needed time until we have a vaccine.

Rajeev Venkayya, M.D., is president of the vaccine business at Takeda Pharmaceuticals and a member of the Coalition for Epidemic Preparedness Innovations board. He served as the special assistant to the president and senior director for biodefense at the White House from 2005 to 2007 and was the principal author of the National Strategy for Pandemic Influenza.

  • It does not make sense when you say that a mask does not prevent someone from getting the virus. We know if you are not hygienic, touch your face or do not wash your hands your risk is much higher to contract the virus. If the masks prevents a person from spreading a virus through coughing or sneezing , then a mask can prevent another person who is wearing a mask from inhaling the virus from the person who has it. i believe they help both people. Seems like common sense

  • These are very good ideas and supported by many other experts in public health but the Achilles heel seems to be testing. Health authorities bungled the launch of testing in the US but the ongoing drag is due to the shortage of reagents to utilize the tests. Reportedly, there is no likelihood of ramping up production to meet the need to test as described. What then?

  • I have a few questions regarding mass usage of surgical face masks:

    1) In Asia it is already a costume to wear those in public places. Did it work to contain the outbreak?

    2) having given that SARS-Covid19 virus lives long on surfaces, and on cardboard it lives almost the double the time it did its predecessor SARS virus, is it plausible to say that it would be the same for paper? If so, given that surgical face masks are mainly made of paper, should people change them more often than the normal prescription of 4 hours?
    3) in case the virus transmission is “airborne”, hence happening via nano particles/droplets smaller than 10 nanometer, are surgical masks effective in blocking these particles/droplets?
    4) the “asymptomatic” carriers are those not showing respiratory symptoms (as coughing or sneezing)? How do they spread the virus though? Are they positive to rectal swabs? Is their urine contaminated too?
    5) are eyes (congiuntiva) an easier entry point in the body for this virus compared to rhino-pharyngeal track? If so, should I wear a face mask per eye too?
    6) does a UV-C lamp device constitute a viable way of disinfection for reuse of face masks, in particular those as FFP2/3?
    7) wearing an FFP2/3 mask with a valve, is safe against another person wearing a surgical mask?
    8) ok I am wearing surgical mask and gloves, can I stop washing my hands so often during the day?
    9) I have a dry cough, should I wear a surgical face mask and go out freely?
    10) I have diarrhea, but not a cough, should I wear a surgical face mask and go out freely using public toilets?
    11) I wear a surgical face mask, I am on my own having a stroll avoiding to get in close contact with anyone in the outdoors.
    A police officer halts me for checking my ID and understand if I have a viable reason for being outside. He wears an FFP2 mask with a valve, and in close contact to me for a search. He then hands a me a pen to fill a form and fine me cause I am not out for working, doing grocery, etc. 5 days later I develop a dry cough, muscle aching and a fever. Am I gonna be able to pay the fine I am due, or am I gonna die earlier?

  • I think what we need to do small social epidemiological trial. A trial with healthy volunteers to work in an office setting or restaurant settings where 5-10 volunteers comes to work every day wearing face masks and follow social distancing. After day 1, another individual COVID19 positive but mild symptoms, is introduced in to the setting with face mask and social distancing. The infected person can come to work place when symptoms are mild, or rest at home on days not able to come. The incubation period, on average is about 5-7 days so results will be available quicker. Each individual in the trial will be tested daily for the virus. It will show the spread of the infection, mode of infection, asymptomatic spreader and many other aspects of the infection. The trial can be designed to have 4-hour work day and 8-hour work day. It will test the hypothesis that we can open up the economy with face mask and social distancing.
    People are signing up for human challenge,’‘ to test vaccine, it may be easier and quicker to do a trial like this.

  • We have a million cases identified by testing, and though testing has partly caught up with the epidemic, almost certainly several times as many unidentified cases. I do not believe we are going to have contract tracing unless it is done by cell phone, that is just too many people.
    I think the universal face mask idea is crucial.
    I also believe there are some big holes we need to close.
    1. You can buy take out food – so, you are not getting infected by other people in the restaurant, but you have no idea if the food cooks are infected.
    2. There are no laws protecting workers so that they feel no pressure to go to work when sick. Right now, if a worker feels sick, even in a public contact job, say the cook in the take out restaurant, the boss can tell him to come to work or be fired. That needs to be flat out illegal and seriously enforced. The worker also needs no questions asked (because testing is not available really) sick leave.
    And all businesses need to take the temperature of their workers and customers. Any fever, and you get sent home. And any coughing, and you get sent home.
    These may not be the very best suggestions, but right now we have nothing, nothing at all.
    Also, because I say it every time – if we had a wearable system of filter and air pump in a backpack we wore, with a hose carrying the filtered air into a helmet which maintains positive pressure to keep air out, we could end the lockdown as soon as people get such a device – I think it could cost under $1,000. And maybe it would be necessary to have a throwaway filter you change every day for a few dollars.
    This is not a trivial expense but if it worked, and we turned enough factories to making them, we could have the country re-opened safely.

  • Implement all of the above, but also emphasize the importance of good personal hygiene: washing your hands and not touching your face. We have great influence on our risk of contracting the disease by implementing disciplined adherence to good hygiene habits. If we take great care to protect ourselves from being infected, then not only do we not add ourselves to the strain on the healthcare system but also we remove ourselves from participation in the transmission circuit.

  • I agree with Jamie, where do you start. The south Korea system is almost impossible to implement in US. The contact tracing was forced via app. Everyone in the neighbor and city will know if an individual’s test positive or negative. The government will sent bulk text messages to everyone in the community about your test results and ask everyone who knows you or in contact with you to come forward for testing and quarantine. That helped more than testing.
    I think for US to move forward, we need to continue social distancing, wear masks and start to go back to work using these precautions. Special precautions for the vulnerable group.

  • How can we contain it? The antibody testing done in NorCAl, LA and NY have shown it is so why to spread, hundreds of thousands of cases, million in NYC. How could we ever begin to contact trace a disease that is already so widespread?

Comments are closed.