Clean the rooms thoroughly. That’s 1 of the takeaways from a study in Morbidity and Mortality Weekly Report (MMWR) that shows that the RNA of the coronavirus that causes COVID-19, SARS-CoV-2, was detected on surfaces of cabins of the Diamond Princess cruise ship for more than 2 weeks. The coronavirus’s RNA “was identified on a variety of surfaces in cabins of both symptomatic and asymptomatic infected passengers up to 17 days after cabins were vacated on the Diamond Princess but before disinfection procedures had been conducted,” the study states. “Although these data cannot be used to determine whether transmission occurred from contaminated surfaces, further study of fomite transmission of SARS-CoV-2 aboard cruise ships is warranted.” 

Cleaning and disinfecting rooms has been shown to be highly effective in containing COVID-19, according to the US Centers for Disease Control and Infection, which publishes MMWR. (United Kingdom health officials also encourage such disinfection.)  

The Diamond Princess had more than 700 coronavirus cases. It was quarantined for a time off of Yokohama, Japan, and at one point contained the largest outbreak of COVID-19 outside of mainland China. From February 16 to 23, nearly 1,000 persons who’d been on the cruise ship were repatriated by air to their home countries. The 329 people who returned to the United States entered quarantine or isolation.

The data collected about the Diamond Princess experience brought to light the danger asymptomatic carriers of COVID-19 present. 

“The results of testing of passengers and crew on board the Diamond Princess demonstrated a high proportion (46.5%) of asymptomatic infections at the time of testing,” the study states. “Available statistical models of the Diamond Princess outbreak suggest that 17.9% of infected persons never developed symptoms.” 

Of the 3,711 Diamond Princess passengers and crew 712 (19.2%) had positive test results for SARS-CoV-2. Of the, 331 who were asymptomatic, 37 (9.7%) required intensive care, and nine (1.3%) died. Infections occurred also among 3 responders: a nurse, a quarantine officer, and an administrator. 

The study underscores just how much of a moving target COVID-19 remains. 

A recent research letter in the New England Journal of Medicine (NEJM) compared SARS-CoV-2 to SARS-CoV-1, the coronavirus that emerged in the early aughts, but was quickly brought under control. That study found that the 2 variety of coronavirus stayed active on surfaces for about the same time. SARS-CoV-2, according to the NEJM study, is detectable in or on aerosols for up to 3 hours, copper for up to 4 hours, cardboard for up to 24 hours, and plastic and stainless steel for up to 2 to 3 days.

The MMWR study, to which dozens of investigators contributed, for the most part kept the focus on the unique dangers presented by cruise ships. 

“During the initial stages of the COVID-19 pandemic, the Diamond Princess was the setting of the largest outbreak outside mainland China,” the study states. “Many other cruise ships have since been implicated in SARS-CoV-2 transmission. Factors that facilitate spread on cruise ships might include mingling of travelers from multiple geographic regions and the closed nature of a cruise ship environment. This is particularly concerning for older passengers, who are at increased risk for serious complications of COVID-19.”References: 

1. Centers for Disease Control and Prevention. Morbidity and Mortality Weekly Report, March 18, 2020. )…

2. Fang L, Karakiulakis G, Roth M. Are patients with hypertension and diabetes mellitus at increased risk for COVID-19 infection? Lancet. March 11, 2020. DOI:

3. Kuster GM, Pfister O, Burkard T, et al. SARS-CoV2: should inhibitors of the renin–angiotensin system be withdrawn in patients with COVID-19? Eur Heart J. March 20, 2020. ehaa235,

4. Hughes, S. COVID-19 and angiotensin drugs: help or harm? Medscape. 3-25-20. Medscape website.