Different viruses can be most transmissible (able to spread) at different times. For instance, influenza (flu) is most transmissible at or just before the onset of symptoms. Whereas SARS is most transmissible at 7-10 days after symptom onset.
A team from Wuhan China created models based on data from two different studies of patients with COVID-19.

The researchers found that the highest viral loads on throat swabs collected were when symptoms started. The loads rapidly declined during the next 7 days. They concluded that about 44% of secondary cases among people in close contact (households) were infected in the 2 days prior to the onset of symptoms. Now this is based on modeling since no samples were collected in patients prior to onset of symptoms.

But if this is correct, then aggressive tracing of contacts will be even more critical than quarantining!

References: He X et L. Temporal dynamics in viral shedding and transmissibility of COVID-19. Nat Med 2020 April 15; [e-pub]. (https://doi.org/10.1038/s41591-020-0869-5)

This is a great article from a physician and anthropologist who has experience with fighting pandemics and developing a plan to transition people back to a virus-free future.

He calls it: Five Elements, five weapons: social distancing, testing, contact tracing, isolation and treatment.

Read more…

Transitioning To Safety

A new survey right in the heart of silicon valley looked for antibodies for COVID-19 in over 3000 residents of Santa Clara County. What was found was that the infection was more widespread and less deadly than we believed.

What does that mean?

Well, with limited testing available in the beginning of this pandemic, county’s were only testing those that were sick with moderate to severe symptoms. This doesn’t give us the true picture of the prevalence of the disease since over 80% of people had mild or no symptoms at all and were not tested. But now we have more testing available so we can test more people to get a sense of the numbers that really had COVID-19. This survey in Santa Clara Country tested immune system antibodies to the virus  which tells us if  people had been infected at some point even if they had no symptoms. The larger the number of people who had the infection but went unnoticed, the lower the death rate may be.

There are some biases in the survey which needs to be considered.

Even if this virus is less deadly than we once thought, we still need to be diligent in taking precautions to avoid spread of the virus and follow “shelter-in-place” orders until we hear otherwise. Overall there are more than 30,000 COVID-19 deaths in the U.S. so it’s hard to find good news in that. People are still getting infected and getting sick. We need to hang in there…

More testing will continue to be done and we just need to wait and see how deadly this virus really is.

Covid-19 Testing Shows More People Infected But Less Deadly Than Thought

In a bid to continue to limit the spread of COVID-19, many states are now issuing a strong recommendation to wear a face mask whenever you leave your home for essential functions.  A “stay-at-home” order is becoming increasing popular in each state and we are starting to see more and more people wearing DIY masks when out in public. But now I’m seeing runners and those riding their bikes also wearing masks? What’s the deal?

This is a great article from our hometown pulmonologist in Boulder (a huge riding community) that explains why wearing masks may be a good idea…

Masks while biking