Question: I’ve seen a lot of news stories state that people with preexisting respiratory conditions, such as asthma, are at a higher risk of death from COVID-19. But those news stories rarely, if ever, mention if the severity of the diagnosis is important. For example, if someone, even a young person, has a mild respiratory condition, do they have a significantly higher risk of dying from COVID-19? Or is that person only at a significantly higher risk of death if their respiratory condition is so severe that they consistently require heavy medication or hospitalization?

Answer: We still have limited data, so we’re operating with uncertainty. While we are still unsure of the true case fatality rate of COVID-19, WHO recently cited case mortality rate of 3.4%.

· COVID-19 is the most dangerous to those age 60+, with increasing age associated with increased risk of adverse outcomes, including death. Data from China show that the mortality rate among those age 80+ is 14.8%. Note: As people age, they are also more likely to have underlying conditions that put them at greater risk — conditions like heart disease, diabetes, and lung disease. Data from China also show that co-morbidities can increase risk of death by up to 2.5x. Again, because data are limited, we don’t have much understanding of how serious underlying health conditions among young people influence their disease progression.

· So far, we know that young people are at very low risk of dying of COVID-19, regardless of underlying conditions. Indeed, young age seems to be protective. Data from China show that people under age 18 made up only 2.4% of all reported cases and only one person age 10–19 died. So far in South Korea, no one under age 30 has died. In Japan, no one under age 50 has died.

· Finally, when we hear about underlying conditions (co-morbidities), we’re talking serious underlying conditions rather than mild conditions.

Question: If a person tests positive for COVID-19, are they actually positive? What about someone whose test results are negative?

Answer: All of the coronavirus tests currently being used start with a technique called polymerase chain reaction (PCR), which can detect tiny amounts of a virus’s genetic material. This means that tests for COVID-19 are highly sensitive. Generally, a positive result really is a positive result. [minor caveat here is that tests should be confirmed as testing quality issues like contamination can lead to false positives] There are, however, several challenges with PCR testing:

· Because PCR tests pick up the virus’s genetic material, we still don’t know how long a person will test positive after they have recovered from COVID-19. Recent case reports from China showed that several folks who had recovered from coronavirus were still testing positive 5–13 days after hospital discharge. We need more information to know whether there are any implications for ongoing transmission and/or what to make of a positive test result among those who have recovered from illness or never showed any signs of illness.

· Even though PCR tests can pick up tiny amounts of genetic material, it still requires the virus to be replicating in the body for some time. This means that a person can test negative while simply being in the early stages of the coronavirus infection. Here, a negative result may not mean that the person is actually negative. This is why retesting is important for those who have been exposed to the virus. Resting has been regularly conducted among those quarantined.

· PCR requires more skills and is therefore less widely available than other types of tests. For example, PCR testing is more complex than rapid diagnostic testing that your doctor can conduct for the flu. This means that testing is lab-based rather than bedside-based. PCR testing is much more sensitive than rapid flu tests, which is important in places where coronavirus is not yet endemic; we do not want to see many false positives when we’re actively trying to identify all cases and their contacts!