Dr. Dora Anne Mills: How science will guide us out of the coronavirus crisis

I often say the most predictable thing about an epidemic is its unpredictability. Compounding this current worldwide epidemic, we are facing two firsts: a first pandemic in history with a coronavirus; and a pandemic with a novel coronavirus. Therefore, unpredictability is built into the fabric of our mainsail.

It is understandable if we sometimes feel we are navigating through the rough waters of this pandemic without a rudder. However, every week we are learning more about this virus. And as we learn more, science is becoming a sturdier rudder.

With several renown infectious disease epidemiologists having recently shared their discernment of what this virus is teaching us, I have tried to very succinctly summarize some current gleanings.

First, there are several unknown factors about this virus that will greatly influence the course of the next several years.

Seasonal Variation: Does SARS-CoV-2 (the virus that causes COVID-19) exhibit seasonal variation? For instance, will it simmer down in the summer, and exhibit increased activity in the winter? Most coronaviruses that SARS-CoV-2 most closely resemble have seasonal characteristics in temperate climates. If that is the case, we may experience a relatively mild summer. But we also may experience a surge in COVD-19 later this fall and winter, which unfortunately could be concurrent with seasonal influenza.
Duration of Immunity: How long does immunity to SARS-CoV-2 last for those who have been ill with COVID-19? The coronaviruses that SARS-CoV-2 most closely resemble provide immunity that wanes over a period of several months to five years. This means it may be more challenging to reach long-lasting herd immunity, even in those places that are experiencing large surges.
Cross Immunity: Is there cross-immunity between SARS-CoV-2 and other coronaviruses, such as those that cause colds? If so, this could be helpful and explain why children are relatively mildly impacted by COVID-19. It can also make it challenging to develop antibody tests with a high degree of specificity (since cross immunity could cause false positives on antibody tests).

There are also unanswered questions regarding human behavior, the answers which will impact the course of the next few months.

Social Distancing: How and when will states and countries lift and reimplement social distancing and related control measures?
Vaccine and/or Treatments: When will there be a vaccine and/or treatment, and how effective will they be?
Travel: When and how will we have reintroductions of COVID-19 due to travel, e.g. Mainers who leave and return, as well as those who travel here?

We also do not have studies on the comparative effectiveness of different social distancing measures on this coronavirus pandemic. For instance, we do not know the relative public health effectiveness of closing schools versus closing non-essential businesses. There are countries and states that are ahead of us on the epidemic curve, so as they reopen, we should closely monitor and learn from them.

What does the future look like?

We can expect ongoing threats from SARS-CoV-2, mainly outbreaks and surges, until there is herd immunity. This is unlikely to be attained until an effective vaccine has been widely administered. Recent analysis shows herd immunity may not be reached until at least 82% of the population is immune.
We should prepare for ongoing social distancing — to one degree or another — and possible substantial resurgences of infection with a return to more intensive social distancing measures. This is especially true if the virus exhibits seasonal characteristics resulting in a rise in transmissibility in the winter, which could coincide with influenza.

As we reopen (health care and other businesses), it is imperative we ramp up, closely monitor, and maintain:

Testing: ensure widespread easily available tests (PCR) to identify patients and monitor for outbreaks and surges.
Patient Monitoring: Intensely follow up patients who test positive to monitor their health (people with COVID-19 can deteriorate 7 – 10 days out) and assure they have what they need for isolation.
Contact Tracing: Connect with patients’ close contacts from the patients’ infectious period, ensure the contacts are quarantined and monitored for health issues during the quarantine period. Contact tracing is important for minimizing viral transmission as well as calculating the R0 value (how many people does one patient typically infect) and assuring R0 is maintained as low as possible.
Social Distancing Compliance: Maintain ongoing social distancing with intermittent higher intensity when outbreaks or surges are detected.
Healthcare Surge Capacity: Maintain increased and unused critical care and non-critical care hospital capacity for surges.
PPE Supplies: Ensure there is sufficient PPE for all of health care, first responders, and essential services.
Disease Tracking: Ensure there is adequate daily monitoring of viral transmission, including of cases, hospitalizations and deaths in order to ensure there is decreasing or low levels of viral transmission and to detect outbreaks and surges early. This is critical since this virus has been shown to surge and overwhelm health care systems very rapidly.

Two future resources that may assist us:

When a reliable antibody test is available, this should be used to determine the extent and duration of immunity.
Mobile phone apps such as what Google and Apple are working on, could also help with monitoring, though privacy concerns need to be addressed.

Until there is widespread effective vaccine and/or treatment, we can expect our federal and state governments will use the three knobs available to them to influence the R0 (the variable that indicates on average how many people an infected person is infecting, the goal is to keep it 1 or below):

Isolating patients and tracing and quarantining their contacts
Social distancing mandates
Border and travel restrictions.

Governments around the world will be challenged to balance the health of their citizens, the freedoms of their population, and economic constraints.

With widespread testing, monitoring of patients (tracking and isolation), and contact tracing and quarantine, distancing measures can be timed to avoid overshooting critical care capacity. We will most likely need ongoing social distancing with intermittent intensity, yet there are many uncertainties, and how this journey unfolds is unclear.

As Marc Lipsitch, a leading infectious disease epidemiologist said recently, “we’ve managed to get to the life raft, but I’m really unclear how we will get to the shore.” Let’s hope for fair winds and following seas, but hold tight onto the tiller of the rudder of science.

Dr. Dora Anne Mills is the chief health improvement officer for MaineHealth and former head of the Maine Center for Disease Control and Prevention.