This post summarizes what we know right now about the SARS-CoV-2 virus and the disease it causes, COVID-19. The information contained in this post may change as the situation changes, or may become obsolete. We will attempt to update if any of this changes substantively.
News and social media outlets have fallen short of useful during this public health emergency. Rumors and anecdotes are treated as evidence, and simple public health messages are drowned out by political and financial sector analysis. For example, a fake message of “tips” attributed to the Stanford Hospital Board included the advice to “take a few sips of water every 15 minutes.”
In the UK, the National Health Service has launched a “counter-disinformation unit” to combat hoaxes around the coronavirus (SARS-CoV-2) and COVID-19. This is not just a fantastic use of the double negative, it’s also a good idea.
To both the lay and scientific audience, I say please take the time to check every news or social media post against DSHS, CDC, WHO websites, or peer-reviewed sources such as articles found on PubMed. Good posts will include links to their source material as well.
What we know right now (Updated April 5, 2020)
The median incubation period between transmission and symptom expression is approximately 5.1 days (95% CI: 4.5-5.8). About 98% of cases see symptoms within 11.5 days. A small fraction may incubate longer than 14 days (the current self-quarantine recommendation). Other cited reports have placed the median incubation period at 6.4, 5.0, 5.2, and between 3 and 6 days. However, these analyses excluded a large number of mild cases, for which incubation times may differ.
Regarding the timing of transmission, the CDC reports the following:
“It is possible that SARS-CoV-2 RNA may be detectable in the upper or lower respiratory tract for weeks after illness onset, similar to infection with MERS-CoV and SARS-CoV. However, detection of viral RNA does not necessarily mean that infectious virus is present. Asymptomatic infection with SARS-CoV-2 has been reported, but it is not yet known what role asymptomatic infection plays in transmission. Similarly, the role of pre-symptomatic transmission (infection detection during the incubation period prior to illness onset) is unknown.”
This last part is obviously a major concern, leading to all the reports of “stealth transmission,” among other euphemisms, in the media.
Updated: This asymptomatic infection and transmission is the central argument to the recent pivot by the CDC to recommend use of cloth masks by healthy individuals “in public settings where other social distancing measures are difficult to maintain (e.g., grocery stores and pharmacies), especially in areas of significant community-based transmission.” The Medical Care blog recently posted a fantastic guide to crafting homemade masks (paired with the CDC recommendations).
This virus is TOUGH!
Updated: The following discussion references the very same studies that were later (March 28, 2020) cited in the report from the National Academies of Sciences prompting the consideration that healthy individuals should wear cloth masks in public.
We now have the first answers to a question I’ve been hoping to see for months at this point. There was plenty of evidence that SARS and MERS (former coronavirus outbreaks) were able to survive on surfaces for hours at a time and required disinfection to remove. We now have evidence (published March 17) on the relative ability of SARS-CoV-2 to endure on inanimate surfaces.
It appears that viable SARS-CoV-2 can survive in aerosol droplets for over three hours, possibly much more. The virus is more stable on plastic (>72 hours) and stainless steel (>48 hours) than on copper (<4 hours) and cardboard (<24 hours).
A hospital-based case series (published March 4) also showed that viral samples could be found all around a patient’s room (including the air outlet fans) and bathroom (bowl, sink, door handle). Air samples and tests of personal protective equipment (PPE) were negative except for one shoe cover. Samples collected after “routine cleaning” (which is actually a thorough disinfection by household standards) were all negative.
However, the possibility of viral transmission through aerosolized fecal matter [commentary on evidence in the journal Gastroenterology: pdf] has been under-reported (author’s opinion) and could lead to potentially serious complications – especially in the healthcare setting where toilet lids are commonly removed.
Updated: Transmission through the eyes (droplets contacting eyes or touching the eyes with infected hands) also appears likely.
Healthcare Utilization Guidance
I’ve identified four major themes from the medical care utilization guidance from public health and healthcare providers.
1. There’s no reason to go to a hospital unless you are at increased risk* or need medical treatment for your symptoms.
Please refer to the CDC testing guidelines for support in making the decision to seek testing and what symptoms of severe illness to monitor in yourself or your loved ones.
This doesn’t mean that you should avoid healthcare interactions when appropriate. Stay in touch with your primary care doctor and coordinate care with clinic appointments. People with mild or typical flu symptoms are able to recover at home.
The National Health Service in the UK has released a very comprehensive guide to what self-isolation can and should look like, although not everything translates for an American audience. The CDC has provided guidelines since February on home care for those with COVID-19 and to help your primary care doctor (or teledoc) know whether or not you need to go to the hospital. The emergency department is only for those who need the most critical care and is not designed to treat typical flu symptoms.
Until testing becomes more widely available, the chances are low that you will get tested and find out whether your symptoms are a result of infection with the coronavirus. Hopefully, this will change in the coming week(s). Even when commercial or widespread testing becomes available, don’t go to the ED with mild or typical flu symptoms or if you just want to be tested!
On the flip side, some people may not seek care when they should. There is a well-known, but complex, gender disparity in healthcare-seeking behavior that shifts with increased age. Obviously, those who are at risk* of serious COVID-19 illness should seek medical treatment when they become ill. Unfortunately there are some people who will avoid taking this step when they should.
2. Call first! Do not show up unannounced if you think you’re sick with the virus.
If the proposed idea of drive-through viral testing services tells you anything, it’s that your public health and healthcare institutions want to move patient interactions outside of the healthcare setting as much as possible. The most acute treatment centers will soon be overwhelmed with the most severe cases. Clinics will be busy managing treatment for those who can recover in the community.
The last thing clinics want is for infection to spread in their workplace or through their workforce. I’ve already heard multiple stories from provider colleagues about patients walking into an office and then declaring that they suspect infection. At that point, it is much more difficult to properly prevent transmission. If you are sick, don’t risk taking your healthcare provider out of commission! Call ahead!
3. Access telehealth resources whenever (and wherever) possible.
This blog had an excellent post last week and an update yesterday on telehealth during the COVID-19 and SARS-CoV-2 outbreak. Telemedicine has the potential to help prevent spread of disease by protecting the healthcare workforce, while permitting providers to effectively and efficiently manage community illness. While telemedicine may not decrease costs, right now the system is more concerned with a) increasing access to care [pdf] and b) moving healthcare encounters to non-infectious settings.
Avail yourself of this resource if it is available to you. Many employer-sponsored health insurance programs already have this option available. Other insurers, including Medicare and Medicaid, are encouraging use of telehealth services by relaxing regulations and establishing payment parity. Community clinics are likely to provide a lot more telehealth services in the coming weeks and months.
4. Masks are a priority to keep people with infection from spreading it, not necessarily to protect healthy people from infection.
Updated: Regardless of the CDC’s recent pivot to recommend cloth masks for healthy individuals, there is still a need to conserve surgical masks and especially N95 masks for groups where they can help the most (healthcare providers and people who are sick). If you have supplies of either of these types of masks, please consider donating them to a healthcare provider in your community.
Healthcare institutions need masks. In the coming weeks and months, they are going to be highly focused on controlling the exposures to this disease in order to protect their personnel. The CDC is already releasing and constantly updating their guidelines on how to optimize these supplies in the healthcare setting.
When worn correctly and consistently, masks are likely help to prevent infection by respiratory illness, reducing the risk between 67 to 80% in studies of influenza transmission within households. Consistent use was a major factor in these findings, with the preventative effect greatly diminished if compliance wasn’t taken into account.
There is also some evidence that they are more helpful in preventing coronavirus-infected individuals from spreading the disease than protecting healthy people from contracting it. In addition, healthcare providers and staff interact with multiple potentially infectious and at risk individuals in a given shift, making them highly vulnerable to infection and increasing their potential to become super-spreaders. This is why the priority is to make sure that healthcare institutions have a supply to protect their workers by providing masks to those with suspected or confirmed disease first, supplying their workforce second, and why distributing masks to healthy individuals is a lower priority.
Conclusions
tl;dr – If you suspect you are infected or have symptoms, do not go to work and do not travel. Call your doctor’s office before you go in for an appointment. Be ready to report your symptoms, recent travels, and possible exposures. They may suggest a conversation over videoconferencing software (telemedicine) before or instead of seeing you in person. If you have symptoms, wear a mask to protect those around you, including your healthcare providers.
Ben King