The Surge is Coming: The Herd Responds

The Surge is Coming: The Herd Responds

Washington Post

Anya Jayanthi, Science and Technology Editor

On Thursday, March 12, at around 10:50 a.m., students were heard shouting in the hallway, “Early dismissal!” Soon the news was confirmed; we would be sent home because of concerns about a new viral illness spreading through the community called COVID-19.

What followed was an extraordinary series of events: schools closed, worship services cancelled, and businesses shuttered, causing them to experience financial strain. Studies even show that quarantine can increase the risk of domestic violence and mental disorders such as anxiety, depression, and obsessive compulsive disorder.

Key questions remain on everyone’s minds. What is the scientific logic that supports entire communities coming to an abrupt halt? What are medical professionals doing? What can we do? What does the future hold, and how much longer will this quarantine last? One thing is clear: the country is preparing for something that we have not seen in our lifetimes.

“The surge is coming, based on what we’ve seen in other places (Italy, New York, Seattle, China),” says Dr. Indira Gurubhagavatula, M.D. M.P.H. She is referring to a spike in the incidence of new cases (the measured number of people infected with COVID-19). Without intervention, a large “surge” has the potential to exceed the capacity of the healthcare system, including beds, workers and equipment.

Here in Lower Merion and the Greater Philadelphia Area, as 77 COVID-19 cases have been confirmed and more unconfirmed cases are likely, fears of an uncontrolled surge continue to rise. The goal then, is two-fold: to expand capacity and to limit demand.

First, healthcare systems are focusing on expanding capacity. In anticipation of the surge, which is expected in the coming days, hospitals have cancelled nonessential surgeries and procedures, so beds and personnel are available.

This measure also preserves personal protective equipment (PPE) (masks, gloves, gowns, face shields and cleaning supplies), because the nation faces a dire shortage of PPE due to the lack of a national stockpile, individuals hoarding the limited supply of PPE that can be purchased and others buying up and then reselling limited PPE at high prices. 

Without access to PPE, healthcare workers can become sick and quarantined, which further limits the numbers of available workers. Furthermore, because some people are infectious before they experience any symptoms, and we are experiencing a lack of readily available testing, healthcare workers could spread the disease to patients or peers.

This can have fatal consequences, Dr. Gurubhagavatula explains, because an inadequate medical workforce means that patients may not receive needed healthcare. Hoarding masks and other PPE can cost lives.

Second, healthcare providers themselves are practicing social distancing to limit the number of new cases, and hence demand for services. Many have switched to telemedicine, some are even FaceTiming patients! Doctors trained in intensive care who can operate ventilators are needed.

Italian hospitals are even retraining doctors from other specialties to work in ICUs and ERs. In Montgomery County and other locations, doctors are being redirected to work in COVID-19 testing centers under tents that have been set up in parking lots. 

Outside of healthcare, some companies are looking at repurposing their assembly lines to create medical supplies (Ford, for instance, promised to begin producing ventilators), similar to war times when manufacturers made supplies for the military.

These measures may not be sufficient, and a large surge would be devastating. Healthcare workers in Italy and New York are facing profound ethical dilemmas as they are forced to consider drastic measures including rationing of ventilators and withholding life support in severely ill patients. 

COVID-19 can lead to chronic complications, such as loss of lung function, and can be fatal in elderly people, infants, immunodeficient people (such as cancer and heart disease patients) and children of all ages. COVID-19 reports children in China show that “the proportion of severe and critical cases was 10.6 % for children younger than 1 year, 7.3% for those 1 to 5, 4.2% for those 6 to 10, 4.1% for those 11 to 15, and 3.0% for those 16 to 18.”

These percentages could increase if children who are unreported (not tested but may have the disease) are counted. However, while these percentages may be small, the absolute number of children experiencing severe and critical cases is unacceptably high. Treatable complications may not be addressed if the surge overwhelms hospital resources, causing needless illnesses and deaths.

So how can we prevent this? The idea is we “take turns” using healthcare resources, rather than overloading the system all at once.

On an epidemic curve, the incidence of disease is measured over time. The term “flatten the curve” comes from this concept—if the number of new cases rises slower and stays the same (flat) over a longer period of time rather than overloading the healthcare system with a sudden, abrupt surge, we can save lives, because healthcare resources will be available for each in turn.

Moreover, delaying contracting the illness gives researchers time to develop vaccines and medical therapies, and manufacturers to make PPE. 

Flattening the curve is not as hard as it sounds. When a new infection like COVID-19 enters a community, how fast the curve grows depends on a number of factors: its mode of transmission, how viable it is to infect others outside the body and for how long, its R0 value (discussed below), whether people are infectious before they become symptomatic (displaying symptoms), and human behaviors.

The mode of transmission is how the virus is spread. COVID-19’s mode of transmission is predominantly droplet (meaning through sneezing and coughing), fecal-oral and sometimes airborne (through aerosols). Studies have found that COVID-19 is viable for hours or even days on cardboard, metal, and plastic, and in aerosols. The R0 value is a measure of the number of people that a single person usually infects. COVID-19 has an R0 of 2-3.

If each infected person infected 2-3 others, then the incidence of new cases would grow exponentially. By contrast, influenza has an R0 of 1-2, and measles an R0 of 15. 

One reason that COVID-19 spreads so quickly is because some people are infectious before they become symptomatic. Children are especially known for being asymptomatic carriers (those who can spread the disease but do not display symptoms).

However, children can also develop immunity and eventually contribute to herd immunity, where those who are vulnerable to fatal consequences are protected from contracting diseases because those around them are now immune. How long such immunity lasts is under investigation. 

At the end of the day, one key question that persists has to do with what the future holds and how much longer social distancing must remain. Human behavior is a fundamental determinant regarding the future of this pandemic in our community.

Some cities, due to inadequate compliance with social distancing, saw continued rises, necessitating statewide shutdowns and shelter-in-place orders (which have been implemented in the Greater Philadelphia Area). In order to end the quarantine as soon as possible, flatten the curve, and bring the R0 value to zero, scientists advise the following: wash your hands, avoid touching your face, and practice social distancing with 100 percent integrity.

Stay AT LEAST six feet away from others. Avoid large or even small gatherings (even people you think do not have the virus could be asymptomatic carriers). The stricter we are with social distancing, the more likely we are to bring an end to this epidemic, and thus, this quarantine.

This principle was clearly illustrated in a Washington Post article: Why outbreaks like coronavirus spread exponentially and how to “flatten the curve.” An interactive simulation shows the dramatic impact of adhering to strict isolation. Each simulation is accompanied by a SIR graph of the number of susceptible (healthy), infected and recovered people in a community, displaying the overall magnitude of the surge (the red hill) as a function of the degree of social distancing.

The simulation powerfully shows that with more and more effective social distancing, the peak of the curve, rather than being a large spike, flattens progressively to a small plateau. Eventually, scientists predict that 40-70% of the world will become infected. Yet all the simulations show that eventually, the disease disappears, as more and more individuals become immune, protecting other vulnerable individuals because of “herd immunity.”

So distance yourself! And don’t hoard PPE. By staying home on your couch, you could be saving someone’s life.