A health care worker administers a COVID-19 test at a Maine Medical Partners drive-in clinic on St. John Street in Portland on Thursday Dec. 17, 2020. Credit: Troy R. Bennett / BDN

Dr. James Li is a MaineHealth emergency physician and the town of Friendship’s health officer and emergency health services director.

I’m one of the doctors who calls you when you test positive for COVID-19. As our cases have increased over the past weeks, I’ve spoken to hundreds of Maine residents, as well as patients in other states overwhelmed with cases.

As an emergency physician with public health and emergency services roles for over two decades, I answer many of the same questions from my COVID-19 patients. Some have asked me to write down my answers as a resource. This is for them and COVID-19 patients everywhere.

We have been neglecting airflow as a mitigating factor.

Indoors, the number of viral particles increases as the time that infected people exhale into that shared airspace increases. The more the air gets contaminated, the more people get infected. The number of viral particles that a person inhales relates to the severity of their infection.

Many of my patients ask me why the severity of pandemic cases has dropped or why their symptoms seem milder than those of patients last year. Based on public health education, many more people are wearing masks, avoiding indoor public spaces and carefully choosing where to place their hands. That has generally led to a reduction in viral particle numbers in places that earlier were severely contaminated.

TRACKING THE CORONAVIRUS IN MAINE

But we have largely left out an important point about getting fresh air indoors. Unless indoor air is replaced by fresh outdoor air, viral contamination increases with time. To prevent new infections, periodically flushing indoor air and replacing it with uncontaminated outside air is at least as important as wearing masks.

If you test positive and live with others, turn on your vent fans.

For infected patients sharing their household with others, fresh air exchange can be enhanced by turning on bathroom and kitchen ventilation fans and leaving them on. Indoor air is pushed out and fresh air is pulled in through small spaces in the walls, doors and windows to replace it.

Opening exterior windows and doors several times a day allows fresh air to replace contaminated air inside quickly. This technique sounds simple but is so effective that it is built into many hotel and hospitality pandemic cleaning guidelines, including AirBnB and others.

For a higher-tech solution, inexpensive HEPA filters actively remove viral particles from indoor airspaces. Some of them combine an internal UV light that further kills any virus trapped by the filter paper inside the device. We installed two such combination HEPA-UV light filters in Friendship’s town office early in the pandemic at a total cost of about $250. This is a solution that works well for both residential households and commercial spaces.

Masks aren’t perfect, but they are crucial. Get the best one you can.

My patients often ask why they got infected despite being meticulous about mask-wearing in public spaces. Masks reduce but do not eliminate the number of inhaled viral particles when breathing contaminated air. The better the mask, the fewer particles are inhaled. That’s why physicians, paramedics and nurses wear N95 masks when caring for COVID-19 patients.

But even those masks don’t offer full protection if the airspace is greatly contaminated, something we learned when many Italian doctors and nurses died of COVID-19 despite wearing N95 masks, gowns, gloves and face shields. They were caring for patients in hospital settings with such high levels of contaminated air that nothing short of a biohazard suit with its own oxygen supply could have prevented the inhalation of viral particles.

For reducing the number of viral particles that a wearer inhales in contaminated airspace, N95 masks are the medical standard. Some public health experts have argued from the beginning that N95 masks should be mass-produced for general population use, that widespread N95 use outside of health care settings could be as effective as shelter-in-place lockdowns for ending the pandemic. I completely agree, but the reality is that N95 masks are still unavailable to most people.

For infected patients worried about spreading COVID-19 to their housemates, I recommend wearing the best mask obtainable. Two things make a mask effective: the thickness of the material and good coverage of the nose and mouth. For those reasons, wearing two masks in high-risk situations further reduces risk of infection.

The first few days are usually the worst.

COVID-19 symptoms are diverse. The most common ones I hear from patients are nasal congestion, facial pain, headache, sore throat, muscle aches and fatigue. Many have upset stomachs and nausea. A few have severe diarrhea. For patients without severe illness, coughing is usually more of an annoyance than a serious symptom. Most patients with mild to moderate illness do not have a fever.

Most patients feel the sickest early in the illness, with worsening symptoms in the first two or three days. For those in previously good health, symptoms start to subside around the fourth or fifth day, a point that is commonly reached as a patient loses the ability to taste and smell.

By the fifth day, most cases have declared themselves as mild, moderate or severe. Severe cases are not subtle. Severe patients have symptoms that mostly manifest with breathing difficulties, uncontrollable coughing and high fever.

Common at-home treatments can help people with mild or moderate cases.

Just like cold or flu, home treatment with over-the-counter medication helps relieve symptoms in mild or moderate cases. For muscle aches, headache, sore throat and fever, ibuprofen and acetaminophen work for most patients.

A standard adult dose of ibuprofen is 600 milligrams as often as three times a day — three of the 200-milligram tablets at a time in a typical bottle. A standard adult dose of acetaminophen is 650 milligrams as often as three times a day. That’s two of the 325-milligram tablets at a time in a typical bottle. Some patients can tolerate higher doses, but the doses here are safe for nearly all healthy adults.

For cough, mentholated cough drops and Vicks VapoRub seem to work better than liquid cough syrup. For diarrhea, Pepto-Bismol works and is safer than other antidiarrheal medications. Nausea can often be controlled with diphenhydramine (Benadryl and others), though most physicians are happy to call in a prescription for ondansetron (Zofran), which is safe and more effective.

The minimum isolation or quarantine period is now 10 days.

In December, the U.S. Centers for Disease Control and Prevention updated and simplified guidelines for isolation and quarantine periods. An isolation period is when a COVID-19 patient must stay at home to reduce the spread of the virus to others. A quarantine period is when anyone who has been in contact with a COVID-19 patient – including all members of a patient’s household – must stay at home to reduce the spread of the illness if the virus incubates in those exposed. Unlike other viral illnesses, this coronavirus is most often spread by people two or three days before symptoms appear.

Both isolation and quarantine periods are now set at 10 days, but this is a minimum. For patients, this period should be extended if symptoms are still present at 10 days. High-risk employers such as nursing homes and hospitals may impose stricter requirements.

The CDC still lists 14 days as a recommended period but recognizes that the risk of being contagious is low enough at 10 days to allow patients and contacts the option of ending early (risk averages 1.4 percent at 10 days versus 0.1 percent at 14 days). However, if household members get sick during their quarantine period, they must restart the clock and stay at home a minimum of 10 more isolation days.

At this point, re-testing is not required or recommended because many patients who recover from COVID-19 continue to test positively after being no longer contagious. A negative test at the end of illness with COVID-19 may be reassuring, but a positive test in this setting is confusing and unnecessary.

Get vaccinated when you can. If you need medical help, go to the emergency room.

We now know that most people who get COVID-19 build some level of immunity against future infections. The latest data show that immunity lasts at least five months. Unfortunately, the strength of immunity varies greatly. Some patients get a lot. Some get none. The vaccine provides a consistently superb level of immunity that lasts at least 12 months.

Given the current scarcity, vaccine doses are being rationed to those in the highest-risk categories. However, as supply improves, everyone who wants will ultimately be able to get vaccinated. When that happens, to ensure strong immunity against future infection, I recommend that anyone who had COVID-19 also gets vaccinated.

I can attest that Maine’s best medical resources for patients with severe COVID-19 are found in the emergency room. If you get COVID-19 and need help, don’t go to a walk-in clinic or your doctor’s office. The emergency room is the place with the most expertise and experience caring for sick COVID-19 patients. We’ve learned that early intervention in serious cases makes a big difference in survival, and we’re good at figuring out quickly and efficiently who needs treatment and who can go home safely.