A Primer on the Epidemic of  COVID-19 aka Coronavirus


Marsha Epstein, MD MPH


Adapted from a longer virtual town hall presented on Sunday, April 12, for the BCC community.

I’m the Secretary of the BCC Board of Directors. I was trained as an MD physician and also as an epidemiologist with a Masters in Public Health and two years of additional training in Public Health and Preventive Medicine. I took a whole year of Biostatistics. I worked for LA County Public Health for 28 years. 

Public Health (PH) has been neglected in funding with repeated budget cuts at the Federal, State, and County levels.  PH nurses, PH doctors, PH investigators and epidemiologists are needed right now to do tracing of contacts of COVID-19 patients, but because of these budget cuts we don’t have enough of them.

Now about COVID-19, which is caused by the virus SARS-CoV-2 commonly known as coronavirus. Other coronaviruses cause the common cold and severe pneumonias like SARS and MERS. 

First, some good news. Physical distancing, wearing masks, and staying home works, and has cut the rate at which this disease spreads. COVID-19 hospitalizations and patients needing intensive care in Los Angeles County and California seem to have already peaked and are going down. Deaths are leveling off or declining. Cases in LA County may have started to level off despite increased testing. But my guess is that Californians will need to stay home at LEAST until the end of May. Everyone wearing a mask in public will decrease the rates faster. 

We hear about the number of cases and the number of deaths. For the number of cases, it depends on how many tests are being done and what the total population is. As we test more people, it’s no surprise that we’re going to find more cases.

We don’t have accurate numbers of people hospitalized with COVID-19 outside of LA County and especially outside of California. CDC doesn’t have a national reporting system to know how many people in the country have been hospitalized with COVID-19. Only 12 states collect information on how many healthcare workers have been infected (California is one of them). So the only reliable number is the number of deaths.  As of April 24 there were 18,517 total confirmed cases and 848 total deaths in Los Angeles County, which has a population of 10 million.

Someone who actually has the virus only tests positive 70% of the time. That’s why they may require two tests to make sure you don’t have it. But if the test is positive, it’s very accurate.

25-50% of people who are infected have no symptoms, or at least no symptoms that concern them. That’s why unless you have stayed home and everyone in your household has stayed home, it’s possible for you to have it but not have symptoms. And you would be contagious.

How is this virus spread?  Although it’s possible to catch it from touching an infected surface and then touching your eye, nose, or mouth, MOST infections are spread person to person.  In one reported cluster of cases, COVID-19 was spread from one infected person with mild symptoms to nine others, who then spread it further.

Face masks are very effective in preventing most people from spreading all infections that are spread by breathing. They are only partially effective at keeping you from catching what other people have if they are not wearing a mask. Wearing masks WILL protect healthcare workers, grocery store workers, and others with whom we have to come in contact. Since 25% of more of infected people have no symptoms, you could be infected and pass it on to others.  So always wear a mask when you go out of your home to protect yourself and others.

By sometime next year we should have one or more treatments and maybe a vaccine. There are 440 studies on COVID-19 listed online at clinicaltrials.gov, and researchers all over the world are researching current medications and other molecules that might fight this virus. Seventy COVID-19 vaccines are currently in development worldwide, and three candidates have already started human trials, but they don’t expect to have a vaccine to give until next year.  Hopefully at least one of them will be safe and work well. 

People with asthma, autoimmune diseases, hypertension, HIV, and other chronic viral infections should continue taking their medicines. Patients who need dialysis should continue dialysis.

I personally have stopped going to the grocery store.  Our young neighbors do our grocery shopping for us.  We wipe down food that needs refrigeration and is wrapped in plastic with a 10% bleach solution or transfer it to clean plastic bags.  We leave non-perishables in the grocery bag for three days out of the refrigerator, after which the virus is probably dead.  The virus lasts less than 24 hours on cardboard, but two to three days on plastic and stainless steel.

You can make your own disinfecting solution with bleach: one part bleach to nine parts water to make a 10% bleach solution. And full strength hydrogen peroxide works as well.

There is no need to wear gloves.  Just wash your hands frequently, as soon as you get home if you’ve been out.  And there’s no evidence of transmission from take-out food.

As for herd immunity, with this virus there won’t be any.  Immunity to other

coronaviruses only lasts one to three years. Estimates suggest that anywhere from about half to three-quarters of the population has to catch it before herd immunity takes hold.