Here is one of number of interesting pieces on VIRAL DOSE. The text below is incomplete, the heading is to the original NYT article. In another article there was a discussion of how in India during the smallpox epidemic, local "doctors" were using a needle to capture some of the pus from smallpox sores... in very small quantities and only at specific stages, and using it to "inoculate" people. The result was a very minor illness if done properly, which would then create an immunity. This was one of the first documented uses of inoculation, and it's thought to have originated .... guess where...China!! Thus by the same token, being exposed to a small a mount of Wuhan virus, you are likely to suffer minimal symptoms, and develop immunity. Essentially your immune system can outpace the virus faster. Thus the use of face masks and hand washing, while it may NOT shield you 100%, may block enough virus to result in a minor illness only. In the end, I'd rather have minor flu like symptoms for several days or a week and then an immunity, than avoid it entirely and get hit full force a year from now!
H.W.
As with any other poison, viruses are usually deadlier in larger amounts.
By Joshua D. Rabinowitz and Caroline R. Bartman
Dr. Rabinowitz is a professor of chemistry and genomics. Dr. Bartman is a genomic researcher.
The importance of viral dose is being overlooked in discussions of the coronavirus. As with any other poison, viruses are usually more dangerous in larger amounts. Small initial exposures tend to lead to mild or asymptomatic infections, while larger doses can be lethal.
From a policy perspective, we need to consider that not all exposures to the coronavirus may be the same. Stepping into an office building that once had someone with the coronavirus in it is not as dangerous as sitting next to that infected person for an hourlong train commute.
This may seem obvious, but many people are not making this distinction. We need to focus more on preventing high-dose infection.
Both small and large amounts of virus can replicate within our cells and cause severe disease in vulnerable individuals such as the immunocompromised. In healthy people, however, immune systems respond as soon as they sense a virus growing inside. Recovery depends on which wins the race: viral spread or immune activation.
Virus experts know that viral dose affects illness severity. In the lab, mice receiving a low dose of virus clear it and recover, while the same virus at a higher dose kills them. Dose sensitivity has been observed for every common acute viral infection that has been studied in lab animals, including coronaviruses.
People should take particular care against high-dose exposures, which are most likely to occur in close in-person interactions — such as coffee meetings, crowded bars and quiet time in a room with Grandma — and from touching our faces after getting substantial amounts of virus on our hands. In-person interactions are more dangerous in enclosed spaces and at short distances, with dose escalating with exposure time. For transient interactions that violate the rule of maintaining six feet between you and others, such as paying a cashier at the grocery store, keep them brief — aim for “within six feet, only six seconds.”
Because dose matters, medical personnel face an extreme risk, since they deal with the sickest, highest-viral-load patients. We must prioritize protective gear for them.
At the same time, we need to avoid a panicked overreaction to low-dose exposures. Clothing and food packaging that have been exposed to someone with the virus seem to present a low risk. Healthy people who are together in the grocery store or workplace experience a tolerable risk — so long as they take precautions like wearing surgical masks and spacing themselves out.
A complete lockdown of society is the most effective way to stop spread of the virus, but it is costly both economically and psychologically. When society eventually reopens, risk-reduction measures like maintaining personal space and practicing proper hand-washing will be essential to reducing high-dose infections. High-risk sites for high-dose exposure, like stadiums and convention venues, should remain shuttered. Risky but essential services like public transportation should be allowed to operate — but people must follow safety measures such as wearing masks, maintaining physical spacing and never commuting with a fever.