CAUTION: The news media often reports on articles from the websites of scientific journals that have not yet been peer reviewed by other doctors. It has become common practice to “pre-publish” studies or press releases online before they have been fully reviewed, and many of these reports are sent out by companies with a lot of money at stake.

Existing conditions: In a study from Germany, patients who died from COVID-19 usually had previous serious heart or lung disease, and their autopsies showed that the virus had infected both the heart and lungs. Death had occurred an average of 7.5 days after admission to hospital (JAMA, May 21, 2020).

Masks: There is no hard scientific evidence that masks are effective in reducing the risk of COVID-19 transmission to a person wearing the mask. Wearing a mask helps to protect others from the virus when you cough or sneeze.

Vaccines: More than 100 vaccines against COVID-19 are being developed and more than 10 have already started to be tested.
• A vaccine developed at the University of Oxford has been shown to prevent infection with the coronavirus in rhesus macaque monkeys (bioRhiv, May 13, 2020). See A First Vaccine for Covid-19
• A Chinese study shows that an adenovirus type-5 vaccine against COVID-19 was well-tolerated and provoked protective antibody responses in healthy volunteers (The Lancet, May 22, 2020).

Indoor air: Most cases of COVID-19 come from breathing indoor air. The more virus particles you breathe in through your nose or mouth, the more likely you are to develop COVID-19 disease. The main source of COVID-19 is breathing indoor air where infected people can deposit virus particles into closed spaces that accumulate virus particles over time. Outdoors the virus is more easily dispersed in the air.
• 53 out of 61 choir members came down with COVID-19 after a two-and-a-half hour choir practice on March 10, 2020 in which people sat 6-10 inches apart.
• 30 healthy Korean dance instructors trained together for four hours, and later eight tested positive for COVID-19. One month later, of 217 students exposed to the eight infected instructors, 57 of them ended up testing positive.

How long are you infectious: The infectious period of COVID-19 in symptomatic individuals may begin around two days before the onset of symptoms, and persists for about 7-10 days after the onset of symptoms. COVID-19 patients are no longer infectious after 11 days of getting sick even though some may still test positive. Active viral replication drops quickly after the first week, and viable virus was not found after the second week of illness despite the persistence of PCR detection of virus RNA. The incubation period from exposure to an infected person to developing first symptoms averages about five days (Ann Intern Med, 2020 May 5;172(9):577-582). In a study of 77 cases in Hong Kong, the time from exposure to an infected person to first symptoms after becoming infected was 5.8 days, with 7.6 percent of exposures occurring before the infecting person developed symptoms (Nature Medicine, April 15, 2020;26:672–675).

Remdesivir: In a double-blind, placebo-controlled trial in which 1063 patients hospitalized with COVID-19 with evidence of lower respiratory tract involvement, those given 10 days of intravenous Remdesivir recovered in 11 days, compared to 15 days for those given placebo (NEJM, May 22, 2020). Side effects in both groups were the same. Of these very sick patients requiring supplemental oxygen, a ventilator or extracorporeal membrane oxygenation, Remdesivir significantly helped only those given supplemental oxygen. Healthier patients who didn’t need oxygen and sicker patients requiring a ventilator or a heart-lung bypass machine did not receive benefits. The authors conclude that, “given high mortality despite the use of remdesivir, it is clear that treatment with an antiviral drug alone is not likely to be sufficient.”